networkfundament&#.pdf

TOSHIBA

ELECTRONIC IMAGING DIVISIONNATIONAL SERVICE SCHOOL

DIGITAL CONNECTED PRODUCTSTRAINING CLASS

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NETWORK FUNDAMENTALS

TOSHIBA America Business Solutions2 Musick

Irvine, California 92618

TOSHIBA America Business Solutions Network FundamentalsElectronic Imaging Division 2 Manual

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TABLE OF CONTENTS

Preface ...................................................................................................................................................... 3Disclaimer ................................................................................................................................................. 4

I. INTRODUCTION............................................................................................................................5

II. NETWORKING FUNDAMENTALS – A REVIEW.................................................................................6A. Network Functionality ...................................................................................................................... 6B. Client/Server vs. Peer-to-Peer Networking ................................................................................ 12C. Network Operating Systems......................................................................................................... 13D. Selecting the Appropriate Topology ............................................................................................ 13E. Selecting the Appropriate Media.................................................................................................. 17F. Media Access Methods ................................................................................................................. 20G. Network Architecture...................................................................................................................... 22H. Selecting the Appropriate Connectivity Devices........................................................................ 28I. Selecting the Appropriate LAN Protocol ..................................................................................... 33J. Wide Area Networks (WAN) ......................................................................................................... 43K. Network Operating Systems – Microsoft/Novell Overview ...................................................... 46L. Network Administration ................................................................................................................. 50M. Resolving Common Network Problems ...................................................................................... 52N. Resolving Cable and Network Interface Card Problems.......................................................... 53O. Resolving Printer Problems .......................................................................................................... 54

II. NETWORK PRINTING – A REVIEW ..............................................................................................55A. Network Print Services .................................................................................................................. 55B. Novell NetWare Printing................................................................................................................ 55C. Print Server Process...................................................................................................................... 56D. Windows Printing ........................................................................................................................... 56E. LPR/LPD Printing ........................................................................................................................... 57

IV. CONCLUSION.........................................................................................................................58

V. GLOSSARY................................................................................................................................59


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PREFACE

In order to prepare you for the Electronic Imaging Division (EID) training class,we have developed the Digital Connected Products Training Class, NetworkFundamentals Manual (Manual). The purpose of the Manual is to provide thestudent with a basic review of network printing technologies. The Manualis intended to supplement a students’ course material received during their EIDtraining program and therefore, provide additional resources necessary toimplement and support a given TOSHIBA connected product.

The Manual is not intended to review all current state-of-practice networkingtechniques, nor provide a stand-alone document addressing concepts necessaryto adequately support a LAN administrator or similar network professional. It isunderstood that a student has at minimum a basic, if not intermediateunderstanding of networking concepts prior to attending a TOSHIBA EID digitalproduct training class. Certain concepts essential to network professionals (e.g.,fault tolerance, data backup) will be addressed in the Manual only to the extentthat the student will be aware of that concept in a networking environmentalthough that certain concept may not be directly applied to a TOSHIBAconnected product.

Together, the Manual, course materials, and successful completion of theInstructor-led EID training program will provide an integral part of yourunderstanding TOSHIBA digital network products.


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DISCLAIMER

TOSHIBA America Business Solutions (TOSHIBA) makes no warranty, or representation,either expressed or implied, with respect to this document or its content, its quality, performance,or fitness for a particular purpose. The information is provided on an “as is” basis. TOSHIBAwill have neither liability nor responsibility to any person or entity with respect to any loss ordamages arising from the information contained in this document.


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I. INTRODUCTION

Understanding the fundamentals of a computer network and network-printingenvironment are critical if you wish to sell, implement, configure, and supportTOSHIBA digital network products. The Electronic Imaging Division (EID) ofTOSHIBA offers Instructor-led classroom training programs for each of its digitalcopier products to qualified dealers and technicians. To this end, TOSHIBArequires each student to posses minimum qualifications regarding his/herknowledge of computer networks. A current list of acceptable certifications islocated on TOSHIBA’s FYI site (www.fyi.toshiba.com) under the service/trainingsections.

TOSHIBA also provides technical resources after completion of the trainingcourse by offering telephone support through its “In-Touch Center” (888-879-8247), Color Support Hotline (888-792-6567), and World Wide Web access toproduct documentation (www.fyi.toshiba.com).

With successful completion of the Instructor-led EID training program you willbecome familiar with the installation and configuration of TOSHIBA digitalconnected products in a network environment and be able to support thoseproducts with a high degree of confidence.


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II. NETWORKING FUNDAMENTALS – A REVIEW

A. Network Functionality

OverviewA computer network is a physical and logical electronic data communicationsystem that allows the sharing of resources between multiple users andmachines. A network may be located within a geographically small area (e.g.,within a building) known as a Local Area Network (LAN), span across large areas(e.g., cities, states, or countries) known as a Wide Area Network (WAN), or beconnected to multiple networks such as the Internet.

Any given network (e.g., LAN, WAN) is a collection of interconnected computingdevices and peripherals. In order for a network to function, three essentialcomponents must exist: 1) media, 2) protocol, and 3) a network service.Although there are numerous other components, which make up a computer,peripheral, network, or integrated system, these three components are theessential core necessary to provide shared access on a network.

An example of commonly used media is the cable or wire (including fiber optics)that physically connects the hardware. The most common of these types ofmedia is copper wire known as unshielded twisted pair (UTP). Examples ofcommonly used protocols include TCP/IP, IPX/SPX, and NetBEUI. The lattercomponent, service, is used to provide the direction or management of networksystem services and functionality. Typically a client (i.e., workstation) service isinvoked to act as a redirector or “grabber” of network resources, while a serverservice functions as a “giver” of network resources.

StandardizationWithin a given network environment, many different manufacturers’ products mayexist. In order for data transfer to be successfully accomplished over a network,all hardware and software must work together and communicate in a common“language.”

Communication between computers on a network would be a simple task if asingle manufacturer created all of the components of that network. However,thousands of companies provide networking hardware and software products,therefore, a common standard must exist in order for communication to becompatible, and therefore successful.


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The International Standards Organization (ISO) is a worldwide organization thatpromotes international standards. During the 1980s, the ISO began efforts todevelop a set of protocols that would allow multi-vendor network environments tocommunicate with one another using industry standard protocols. The result ofthese efforts was the development of the Open Systems Interconnection (OSI)Model.

The OSI Model established the standards for communicating with the same peerprotocol layer running on the opposite computer (virtual connectivity) andprovides services to the layer above it, except for the Application Layer. The OSIModel divides data communication into seven functions, or layers, whichdescribe how information flows from one end-user to another. Each layerprepares information for, and communicates with the one above or below it.Table 1 presents each layer of the OSI Model and its respective function,associated network component and protocols/services. The table is provided inorder to present a generic overview of the OSI Model and its relationship tonetwork components; it is not intended to represent a specific operating system,nor is it intended to provide a detailed completeness of all protocols or ISOstandards.


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Table 1. OSI Layers

OSI LAYER FUNCTION COMPONENT PROTOCOLSSERVICES

Application LayerProvides standard services toapplications and end-user interface.Handles general network access, andflow control.

GatewaysSMB, SNMP,SMTP, FTP, HTTP,Telnet, LPR, LPD,RSH

Presentation Layer

Translates data from ApplicationLayer to a format the Session Layercan understand. Performs dataformat conversion. Provides datacompression, encoding, andencryption.

PostscriptRedirector

Session Layer

Allows two applications on differentcomputers to establish, use, andterminate a connection called asession. Synchronizescommunications between computers;controls when users can send andreceive data.

DHCP

Transport Layer

Manages connections and providesreliable packet delivery betweensending and receiving computers.Breaks long messages into severalpackets. Reassembles the packetswhen in receiving mode. Operates inunits of messages.

TCPUDPNWLinkSPX

Network Layer

Translates addresses and routesdata from one node to another.Performs fragmentation and re-assembly, packet switching, androuting. Operates in units of packets.

RoutersIP, ARP, RARP,IARP, Ping, IPX,NetBEUI, RIP

Consists of 2 sublayers. Operates inunits of frames.

BridgesSwitches

SLIPPPP

Logical Link Control (LLC): Defineshow data is transferred over themedia and provides data link servicesto higher layers.

802.1802.2

Data Link Layer

Media Access Control (MAC):Defines who can use the networkwhen multiple computers are trying toaccess it simultaneously

802.3 CSMA/CD802.4 Token Bus802.5 Token Ring802.12 DemandPriority

Physical Layer

Defines physical hardwareconnection specifications, andelectrical and wiring specifications.Responsible for transmitting dataacross a wire. Operates in units ofbits.

HubsRepeaters

The upper layers of the OSI model (e.g., Application Layer) are software orientedwhereas the lower layers (e.g., Physical Layer) are more hardware dependent.


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Most network equipment manufacturers now build their networking products incompliance with the OSI Model.

The purpose of each layer in the OSI Model is to provide a service to the nexthigher software layer. The service consists of dividing communication tasks intosmaller subtasks, which can be utilized by specific protocols at their respectivelayer. Communication between one computer and another begins at theApplication Layer. Data travels down through the layers, across the wire to itsdestination, and up through the layers to the receiving computer’s application.There is a virtual connection between layers from one computer to another(Figure 1).

Figure 1. The OSI Model

Prior to data passing from one layer down to another, messages are convertedinto a more manageable unit (i.e., packet, frame, and bit [Figure 2]).

Network

Physical

Data Link

Application

Presentation

Session

Transport

Application

Presentation

Session

Transport

Network

Data Link

Physical

Computer 2(Receiving)

Computer 1(Sending)

Network Cable/Wire


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Figure 2. Data Packet

When the data message arrives at the next lower layer, additional information isadded to it in order to identify it on the network and insure data integrity (Figure3). This additional information may include addressing (source/destination),formatting, and error checking. When the packet arrives at the Physical Layer, itis processed into bits, which are ready for physical transmission across themedia to the destination computer (Figure 4).

Figure 3. Packet Preparation

Application Header

Presentation Header

Session Header

Transport Header

Network Header

Data Link Header

Frame Preamble

Data Link Trailer (CRC)

Data

Packet

MessageData


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All packets have certain common components. These include:

Header• Source address• Destination address• Alert signal• Clock information• Reassemble sequence code for the receiving computer

Data• Data

Trailer• Error checking component (CRC)

Figure 4. Completed Data Packet

The sending computer breaks data into smaller sections, adds addressinginformation (e.g., source, destination, formatting, and error-checking) to it, andprepares the data for actual transmission to the media, and over the network.When the bits of data arrive at the destination computer, the process isessentially reversed; the bits will be re-assembled as they pass up the softwarelayers. The receiving computer takes the data off the wire, brings in the data viaa network adapter card, strips off all transmission data from the packets, copiesthe data from the packet into a buffer for re-assembly, and passes thereassembled data to the Application Layer. This sequence, although simplified inthis example, is necessary for the transmission of data from one computer toanother in a form that is understood by the receiving computer and ultimately theend-user.

Header Data Trailer


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B. Client/Server vs. Peer-to-Peer Networking

There are three basic configurations a local area network will operate under; apeer-to-peer network, a client/server network, or a combination of the two (i.e.,hybrid). Given the function, there are three basic roles that a computer willassume on a network:

Client – a client will utilize, but not provide network resources,Peer – a peer can utilize, and provide network resources, andServer – a server generally provides, but does not utilize networkresources.

In a Peer-to-Peer network, there is no centralized administration, and userstypically share their resources however they deem necessary. The end-userstores resources on his/her local machine. There are no servers in a Peer-to-Peer network, and therefore the network will generally have little or no security.Peer-to-Peer networks are organized into logical groupings called “workgroups.”

In a Client/Server network, a server provides access to network resourcesthrough centralized administration and security. No computer users can accessthe resources of a network unless a server has authenticated them.Authentication occurs when a user logs onto the network from a client machinewhich has an account on the network server. Server-based networks provide asingle logon procedure which allows users to connect to multiple computers andresources.

A hybrid network is a combination of Peer-to-Peer and Client/Servercomponents. Computers function as clients, peers, and servers, and the networkwill likely have domains and workgroups. Although most shared networkresources will be located on a server, each peer also has the ability to shareresources. Users do not have to logon to domain controllers in order to haveaccess to local resources.

Security Models

Share Level (Password-Protected Shares)Share level security is a simple method that allows any user to obtain access toany resource if the user knows the password to that specific resource. Thissecurity model is used primarily with Peer-to-Peer networks.

User Level (Access Permissions)Security is based on permissions granted to the user during a network logonsession. Permissions are based on the “user level” such as administrator, printmanager, end-user, accounting etc. This method is more secure than the sharelevel permissions, which grant access to resources to anyone who knows thepassword to the shared resource. This method of security is generally used with


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dedicated server operating systems, which maintain an ACL (Access ControlList).

C. Network Operating Systems

The network operating system (NOS) is a supervisory software program thatresides on the server. It controls how the network operates by defining who canuse the network and how information and resources (e.g., printers, modems, andfile servers) are shared with other workstations. Without a NOS, computingdevices would remain isolated even when physically linked. A NOS will provide aset of protocols for accepting requests from clients and responding to thoserequests. In addition, a NOS will provide a shared file system, and securityfeatures.

Most industry standard NOSs operate as dedicated servers and are controlled byadministrators who manage system policies, permissions, profiles, and securityissues. Client computers operate redirectors, which transmit requests fornetwork service to a dedicated network server. Common NOSs include:

• Novell IntranetWare• Microsoft Windows NT Server• AppleShare• Banyan Vines• IBM OS/2 Warp Server• Sun Microsystems Solaris• Unix/Linux

D. Selecting the Appropriate Topology

The physical layout of a network is its topology. The term topology has twomeanings regarding network cabling. One meaning refers to a logical descriptionthat describes how the data signal travels. For example, in Token Ring the datalogically travels in a loop or a ring. The second meaning refers to how thephysical layout of the cable appears. For example, in Token Ring, the cabletopology often physically resembles a star arrangement. Conversely, Ethernet islogically a bus topology, and can be installed as either a physical bus or aphysical star topology.

Three prevalent types of network topologies are star, bus, and ring, and includehybrid designs of each topology. The topology of a given network depends onthe media access method(s) it uses and type(s) of cables that are installed.Whereas small networks with clusters of network devices tend to employ onlyone topology, large networks that span a wide physical area or several floors of abuilding may use a combination of topologies.


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StarA star topology describes a physical layout where cables emanate from a centralhub and terminate at a single computer. Each cable run is a point-to-pointconnection. Token Ring, Ethernet, and ArcNet are all capable of being wired intoa physical star topology. Cable breaks in a star topology usually affect only onestation, however, if the central point (e.g., hub) fails, the entire network will notfunction.

Figure 5. Star Topology

BusA bus topology logically can be thought of as a single cable with two distinctends. Ethernet is logically a bus topology, and when installed with 10Base2 or10Base5 cable (see Section II. E), it is a physical bus as well. Physical busimplementations allow the nodes (devices) to attach at various points along thecable. When a device transmits onto the bus, data travels in both directionstoward the ends of the cable. Each cable end must be terminated with a resistorin order to absorb the signal energy when it reaches the end of the cable. If acable is not properly terminated, each packet may reflect and collide with itselfcausing errors. Cable breaks in a physical bus implementation affect allcomputers attached to the bus.

Figure 6. Bus Topology


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RingA ring topology circulates packets in a loop or a ring. The data on a given ringalways travels in one direction. Each device is physically part of the ring in thatthe signal actually passes into then out of each device. Each device regeneratesand transmits the signal to the next device in the ring. FDDI (Fiber DistributedData Interface) is composed of two rings, one moves data in a clockwisedirection while the other moves data in a counter-clockwise direction. The dualrings can keep the network operational in the event of a cable break.

Figure 7. Ring Topology

Star-Wired RingThe star-wired ring has essentially replaced the ring topology in practical use.Networks based on star-wired ring topologies have nodes radiating from a wiringcenter or hub. The hub acts as a logical ring with data packets traveling insequence from port to port. Similar to a star topology, if one node fails, thenetwork will continue to operate.

Figure 8. Star-Wired Ring Topology


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Star BusThe star bus topology links several star hubs together with bus trunks. If onecomputer fails, the hub can detect the fault and isolate the computer. If a hubfails, computers connected to it will not be able to communicate, and the busnetwork will be broken into two segments.

Figure 9. Star Bus Topology

The topology selected for a given network is based on a combination of severalissues, some of which include cost, number of users, distance between nodes,and scalability. A summary of topology advantages and disadvantages arepresented in Table 2.

Table 2. Topology Summary

TOPOLOGY ADVANTAGE DISADVANTAGE

Bus

Simple, reliable in small networks.Inexpensive, and easy to expandwith BNC connectors andrepeaters.

Difficult to troubleshoot. A cablebreak along the bus will bringdown the network. Heavynetwork traffic can slow a busconsiderably. Each BNC canweaken the signal.

Ring

Every computer given equalaccess to token; no one computercan dominate the network. Ifcapacity is exceeded,degradation is graceful ratherthan a sudden failure.

Failure of one node can bringdown the ring. Adding orremoving a computer from thering disrupts communication.Difficult to isolate problems.

Star

Easy to modify and add newcomputers. Easy to troubleshoot.Single computer failure will notbring down entire network.Supports multiple cable types.

Central point failure brings downentire network. Cost is high dueto centralizing all nodes into onepoint. May require central deviceto switch or rebroadcast signal.


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E. Selecting the Appropriate Media

Cable is what physically connects network devices together, serving as theconduit for information traveling from one computing device to another. The typeof cable utilized for a given network will be dictated in part by the network'stopology, size and media access method. Small networks may employ only asingle cable type, whereas large networks tend to use a combination of differenttypes of cable (e.g., copper wire, and fiber).

The three most common types of cable utilized throughout the world are twistedpair, coaxial, and fiber. A brief discussion of each of these types of cablesfollows.

Twisted Pair CableTwisted-pair cable is a generic term that describes many different cable stylesand specifications. Terminology associated with twisted-pair cabling originatedwithin the telephone company community. Cable may or may not includeshielding; UTP is unshielded twisted-pair while STP is shielded twisted-pair.

UTP wiring, carries signal 100 meters. UTP is susceptible to crosstalk, which issignal overflow from adjacent wires.

STP wiring, carries signal 100 meters. STP has a foil or braided jacket aroundwiring to help reduce crosstalk and to prevent electromagnetic interference.

Figure 10. Twisted Pair Cable

Shielding

STP


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Table 3. Cable Type

CATEGORY MEDIA (TYPICAL) SPEED

1 Voice N/A2 Voice 4Mbps3 Data 10Mbps4 Data 16Mbps5 Data 100Mbps

The number of pairs of wires in a cable is typically specified (e.g., 4 pair or 2pair). Typically solid conductor twisted-pair cable is installed through the wallsand ceiling.

Each in-wall cable typically terminates in a wall plate connection near the userworkspace and at a patch panel near the central hub. Twisted pair cable usesRJ-45 connectors. Patch cables connect the workstation to the wall plateconnection; another patch cable connects the patch panel connection to a porton the central hub. Twisted-pair cabling is manufactured to variousspecifications regarding the number of twists per foot, wire gauge size, andelectrical characteristics (e.g., Category 3 or Category 5).

Coaxial CableCoaxial cable falls into two main categories, thick or thin. With thin cables thereare several styles, for example Ethernet uses one style while ArcNet usesanother. Characteristics such as maximum length, number of devices allowed,and connector types also vary. Thin cable typically uses BNC (British NavalConnectors) connectors.

The core carries the data while the braided metal near the outside providesshielding to prevent interference from electrical noise and crosstalk.

The conducting core and the wire mesh must never come in contact with eachother. Coaxial cable is more resistant to interference and attenuation thantwisted pair cabling. Coaxial cable will transmit voice, data and video.

Figure 11. Coaxial Cable

Outer shield

Insulation (PVC, Teflon)

Conducting coreCopper wire mesh or aluminum sleeve


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Thinnet Coaxial Cable• 0.25 inches diameter• Carries signals up to 185 meters• Known as RG-58 family• 50 Ohm impedance

Thicknet Coaxial Cable• 0.5 inches diameter• Carries signals up to 500 meters• Known as Standard Ethernet• Generally used as a backbone

Fiber-Optic CableFiber-optic cable is constructed of flexible glass and plastic. In fiber-optic cable,the optical fibers (i.e., “glass”) carry digital signals in the form of modulatedpulses of light (i.e., photons). Each glass strand passes signals in only onedirection, therefore a fiber cable must consist of two strands in separate jackets;one strand transmits data and one strand receives data.

Figure 12. Fiber-Optic Cable

Fiber-optic cable is resistant to electronic interference and therefore is ideal forenvironments with a considerable amount of noise (e.g., electrical interference).Furthermore, since fiber-optic cable can transmit signals further than coaxial andtwisted-pair, more and more companies are installing it as a backbone in largefacilities and between buildings. The cost of installing and maintaining fiber-opticcable remains too high, however, for it to be a viable network media connectionfor small networks. Fiber-optic cable transmissions are not subject to electricalinterference and are extremely fast (e.g., 100Mbps- 1Gbps).

Fiber Optic Connector

Optical Fiber (core) Glass Clading

Protective Outer SheathKevlar


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Signal TransmissionThere are two primary methods of data transmission regarding cables; basebandand broadband.

Baseband• baseband systems use digital signaling over a single frequency• signals flow in the form of pulses of electricity or light• the entire communications channel capacity is used to transmit a single

data signal• each device on a baseband network transmits bi-directionally• some devices can transmit and receive at the same time• signals decrease in strength as they travel along the cable• repeaters are used to retransmit the signal along the cable

Broadband• transmission signal flow is unidirectional• signals are continuous and non-discrete• broadband systems use analog signaling and a wide range of frequencies• signals flow across the medium in the form of electromagnetic or optical

waves• requires amplifiers to regenerate analog signals at their original strength• can transmit in the multi-megabit and gigabit range

If sufficient total bandwidth is available, multiple analog transmission systemssuch as cable television and network transmissions can be supportedsimultaneously on the same cable. Since broadband transmission signal flow isunidirectional, there must be two paths for data to flow in order for a signal toreach all devices. A mid-split broadband system divides bandwidth into twochannels; one channel transmits data and one channel receives data.

F. Media Access Methods

In order for computers to effectively share access with other devices over a givenmedium, specific rules must be implemented to enable error-free transmission. Amedia access method defines how computing devices access the network cableand send data. Ethernet, Token Ring and LocalTalk (Apple) media accessmethods are used primarily for connecting desktop machines (computers,printers etc.) to the network, whereas FDDI, CDDI, Fast Ethernet and ATM areused primarily for high-speed backbones, high-speed network access (e.g. fileservers) and very high-speed workgroup applications. There are two primaryapproaches to media access control; 1) contention, and 2) deterministic.

ContentionWithin the contention approach, there are two functional types of media accesscontrol. Each type is used to determine if more than one node is attempting to


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access the network at the same time. They both are based on sensing signalseach computer emanates to the network cable, hence the name Carrier SenseMultiple Access (CSMA). CSMA is used in two different capacities; collisiondetection (CD), and collision avoidance (CA).CSMA/CD uses a method where every node on a network will wait to send dataonly when no other computers are “heard” on the cable. When a computerdetects another computer transmitting, the network adapter card assumes acollision has occurred and it will not transmit its own data. The computer usingCSMA/CD will wait until the network is silent before sending its own data. Thismethod attempts to avoid data collisions caused by more than one computertransmitting data at the same time.

CSMA/CA is similar to CSMA/CD in that each computer waits for a silent cable.However, CSMA/CA does not check for collisions by listening for othercomputers transmitting. CSMA/CA will evaluate whether the data wassuccessfully transmitted by waiting for an acknowledgment from the recipient. Ifan acknowledgment is not received, it assumes the transmission between thetwo computers will be resent, and therefore it will not send its own data. If anacknowledgement is detected, the sending computer will assume a “free” lineand begin data transmission.

DeterministicThis method of media access control allows a level of certainty as to themaximum time a computer will have to wait to gain access on the network. Thisis usually accomplished by passing a token between computers on the network.When a computer receives the token, it is allowed to transmit its data onto thecable. After the recipient has acknowledged the arrival of data, the sendingcomputer will release the token, which allows other computers to capture it(token) and transmit data.

Demand PriorityIt is possible that two computers, listening to the network for silence, maytransmit data at exactly the same time. Demand Priority utilizes the hubs andrepeaters of a network, where data will be given priority if two computers transmitdata at exactly the same time. The data with the highest priority is allowed totransmit first. If the data have the same priority, Demand Priority method allowsfor the transmission of both data but alternates between small blocks from eachcomputer.

Although there are other media access method controls, and newer onescurrently being developed, the aforementioned methods are the most commonways of controlling access in today’s network environments. Table 4 presents asummary of media access control methods.


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Table 4. Media Access Methods (Typical)

ACCESS METHOD ACCESS METHODCONTROL

TOPOLOGY COMMON CABLESUSED

Ethernet CSMA/CD Star or Bus Twisted-pair, coaxial,fiber

Fast Ethernet Demand Priority Star Twisted-pair, fiberToken Ring Deterministic Star-wired Ring Twisted-pair, fiberLocalTalk CSMA/CA Bus Twisted-pairFDDI Deterministic Dual ring, Star-wired ring FiberCDDI Deterministic Star-wired ring Twisted-pairATM Dedicated circuits Star Fiber, twisted-pair

G. Network Architecture

The structure of a network’s architecture is defined by a set of standards andtechniques necessary for designing and building network communicationsystems. There are third-party proprietary architectures such as IBM’s SNA(Systems Network Architecture) and DEC’s DNA (Digital Network Architecture).In addition there are open architectures such as the OSI (Open SystemsInterconnection) Model defined by the ISO.

The following provides a discussion of one of the most common networkarchitectures in existence today, Ethernet. In addition, a brief overview of FastEthernet, Token Ring, LocalTalk, FDDI, and CDDI will be discussed.

Ethernet OverviewEthernet is the most widely used LAN technology in use today. Approximately80% of LANs today use Ethernet for installed network connections. The IEEEspecification 802.3 defines the Ethernet standard. The Ethernet specificationcovers rules for configuring LANs, the type of media that can be used, and howthe elements should be networked together. The Ethernet protocol provides theservices called for in the Physical and Data Link Layers of the OSI referencemodel.

Every Ethernet network adapter is identified by an address. This address is 48bits long, and all manufacturers of Ethernet equipment cooperate to make surethat this address is unique; it is different for every single Ethernet device. Thisaddress is called the MAC (Media Access Control) address.

One element of the 802.3 specification states that Ethernet networks run at 10million bits per second (10Mbps) or at a rate of 100 million bits per second(100Mbps) which is commonly refereed to as Fast Ethernet. The transmission ofdata at these rates is what is referred to as how fast the traffic is on the network.


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In addition to the speed of network traffic, specification 802.3 defines the accessmethod used by computers connected to the LAN. The specified access methodis CSMA/CD.

On an Ethernet network, a single communication environment (the “ether”)propagates signals from one computer to every other computer. All computersare free to put signals on the wire at any time. Occasionally, two computers willsend signals out at the same time. When this happens, a collision is said tooccur. The computer networking hardware is designed to detect such a collision.When a collision occurs, both computers wait a random length of time, and thenre-send their messages.

Ethernet WiringEthernet can be implemented at different data transmission speeds and overdifferent types of media. This portion of the 802.3 Ethernet specificationaddresses the Physical Layer of the OSI reference model. There are severaldifferent Physical Layer (e.g., media) specifications. The following list describesthe different varieties of Ethernet. Note that the first number in the name refersto the speed in Mbps, Base refers to baseband, and the last number represents adistance standard (or a “T” for twisted pair).

10BaseT• 10 Mbps, baseband transmission• Maximum length of a 10BaseT segment is 100 meters (328ft)• Minimum cable length between computers is 2.5 meters• A 10BaseT LAN will serve 1,024 computers• Twisted pair cable categories 3, 4 or 5• Hub to Card/Transceiver distance 100 meters• Backbones for Hubs, Coaxial or fiber-optic to join a larger LAN• Total computers per LAN without connectivity components, 1024 by

specification• Uses RJ-45 connectors

10Base2• 10 Mbps, baseband transmission• Thinnet coaxial cable (RG-58), 0.25 inches diameter• Maximum length of a 1OBase2 segment is 185 meters (607ft)• Five segments connected by four repeaters• 5-4-3 Rule, three of the five segments may be populated• Maximum total network length 925 meters (3,035ft)• Minimum cable length of 0.5 meters (20 inches)• Maximum 30 computers (and repeaters) per 185 meter segment• Maximum number of computers per network without connectivity

components, 1024 by specification• Uses BNC connectors


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Because normal Ethernet limits would be too confining for a large business,repeaters can be used to join Ethernet segments and extend the network to atotal length of 925 meters.

10Base5 - Standard Ethernet• 10 Mbps, baseband transmission• Thicknet coaxial cable, 0.50 inches diameter• Maximum length of a 10Base2 segment is 500 meters• Five segments connected by four repeaters• 5-4-3 Rule, three of the five segments may be populated Maximum

total network length 2,500 meters (8,200ft)• Maximum computer-to-transceiver distance 50 meters (164ft)• Minimum distance between transceivers 2.5 meters (8ft)• Maximum I 00 computers (and repeaters) per segment

5-4-3 RuleA Thinnet network can combine as many as five cable segments connected byfour repeaters, but only three segments can have client workstations attached.Therefore, two segments are untapped and are often referred to as inter-repeaterlinks; this is known as the 5-4-3 rule.

10BaseFLEthernet over Fiber-Optic cable. 10BaseFL (10Mbps, baseband, over fiber-opticcable) is an Ethernet network that typically uses fiber-optic cable to connectcomputers and repeaters.

The primary reason for using 10BaseFL is for long cable runs between repeaters,such as between buildings. The maximum distance for a 1OBaseFL segment is2,000 meters.

100VG-AnyLANDesigned by Hewlett-Packard and combines elements of Ethernet and TokenRing. Defined by 802.12 which specifies a standard for transmitting 802.3Ethernet frames and 802.5 Token Ring packets. Also known as 100BaseVG, VGand AnyLAN.

100BaseX (Fast Ethernet)100BaseT4 (4-pair Category 3, 4, or 5 UTP)100BaseTX (2-pair Category 5 UTP or STP)100BaseFX (2-strand fiber optic cable)

In a 10Base2 network, a single length of coaxial cable connects the entirenetwork. The diagram below presents a 10Base2 configuration using Thinnet(RG-58) cable and BNC connectors.


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Figure 13. Thinnet Bus

Coaxial Cable

Terminator

Connection toComputer NIC

T Connector

The electrical properties of the RG-58 cable system are critical. Propergrounding is vital to correct data transmission. Physical damage to the cable,such as a crimp, can bring down all communication. Missing one of the twoterminators will also prevent communication.

The connection at each computer ismade with a BNC T-connector.

Coaxial Cable

Connector toComputer NIC

T Connector

The computer at the end of the wire usesa BNC - T Connector with a terminator.


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10BaseT and 100BaseT NetworkBoth 10BaseT and 100BaseT networks are wired together using twisted paircable similar to the type that is used for telephone connections. In both cases,the cable must meet rigid electrical specifications. The higher speed 100BaseTmust meet a specification called Category 5. To all outward appearances,10BaseT and 100BaseT networks look physically identical.

Figure 14. Twisted Pair Network

In a 10BaseT or 100BaseT network, all of the computers are wired into a singleconnection point, called a hub. The hub takes the signal out of each computerand connects that signal to all the other computers via ports. Because eachcomputer is connected to the hub separately, a bad cable will only affect a singlecomputer. The cable plugs into the hub and the computer using a RJ-45connector, which is similar to a large telephone jack. BNC T-connectors andterminators are not used with xBaseT network devices.

Figure 15. RJ-45 Connector

Hub


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Table 5. IEEE 802.3 Ethernet

SPECIFICATION 10BASE2 10BASETTopology Bus Star BusCable Type RG-58 Thinnet Coax Category 3, 4, 5 UTPConnection to Adapter BNC T-Connector RJ-45Terminator resistance (OHMS) 50 Terminator Not UsedMax. Cable Length 185 m 100mMax. Segments 5 (using 4 repeaters) with

only 3 populated segments5 (using 4 repeaters) with only 3segments populated

Max. Network Length 925m N/AMax. PCs Per Segment 30 (1024 per network) 1 (each PC has cable to hub)

Fast EthernetFast Ethernet refers to 100 Mbps Ethernet. There are two significant sources ofsupporting technology regarding the implementation of this network type. Onesupports 100BaseVG, a significant modification to CSMA/CD. The second,comprised of more than 80 companies (known as the Fast Ethernet Alliance),supports 100BaseT, which at the MAC layer, retains many of the samecharacteristics as 10BaseT.

100BaseVG and 100BaseT are not compatible with each other or with existingIEEE 802.3 Ethernet standards. They each have their own standards, IEEEStandard 802.3u for 100BaseT, and 802.12 for 100BaseVG. Specific bridges,routers or switches must be used to interconnect these technologies.

Token RingThe Token Ring architecture was developed by IBM Corporation in the mid-1980s and subsequently defined by the IEEE in Project 802. Since Token Ringis IBM's preferred method for networking, it is found primarily in large IBM miniand mainframe installations. Due to the increasing popularity of Ethernet, therate of growth of Token Ring networks has decreased. Token Ring networks usea star-wired ring topology over UTP and STP wiring. A hub (referred to as aMAU [Multi-Station Access Unit]) is at the center of the ring. Two versions ofToken Ring are available: 4 Mbps and 16 Mbps.

Token Ring networks use a token passing media access control mechanism tocirculate packets around the ring. An electronic token travels from station tostation in a single, logical direction. If the token is free, a station can attach datato the token, change the token's status to busy, and then send the token on tothe next station. Each consecutive station then checks the destination addressof the data to see if it should process the data. If the destination address doesnot match the computer viewing it, it then passes the token on. When the stationthat originated the token receives it back, it removes the data from the token andchanges the token status back to free.


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LocalTalkLocalTalk is a proprietary media access method built into Apple Macintoshcomputers and LaserWriter printers. LocalTalk networks are best suited to smallnetworks using Macintosh computers (e.g. an independently networkedclassroom). With LocalTalk, computers are set up in a bus configuration usingboth UTP and STP wiring. LocalTalk transmits at only 230 Kbps or about 1/40the rate of Ethernet. For this reason, many schools and universities areupgrading their LocalTalk Macintosh installations to Ethernet in order to handlelarger file transfers. LocalTalk uses the CSMA/CA media access controlmechanism for transmitting data.

FDDIThe FDDI (Fiber Distributed Data Interface) media access method transfers dataat very high speeds (100Mbps) over fiber-optic cable. Like Token Ring, thisaccess method employs a token passing media access control mechanism totransmit data. FDDI, however, uses a dual counter-rotating ring topology,meaning there are two rings of cable with two tokens circulating in oppositedirections. This set-up creates a relatively fault tolerant network. Manyinstitutions are installing fiber-optic backbone cables to carry Ethernet signalstoday and FDDI signals in the future.

CDDICDDI (Copper Distributed Data Interface) is an emerging technology that usesthe FDDI media access control mechanism over copper (unshielded twisted-pair)cable. It is employed in a limited fashion to connect file servers and highperformance workstations directly to an FDDI backbone. A clear disadvantage ofCDDI is that the cost per port remains too high for it to be considered a viablenetworking solution for the typical desktop computer.

H. Selecting the Appropriate Connectivity Devices

Network AdaptersThe network adapter (Network Interface Card [NIC]) is the physical link betweenthe computing device and the network cable. Typically, a network adapter is acard that slides into a computing device's expansion slot, providing a connectorfor attaching the network cable. A network adapter card is seated in either anISA (Industry Standard Architecture) 8- or 16-bit slot, or a PCI (peripheralcomponent interconnect) 32-bit slot.

Network adapters can also be external units or built directly onto a device'smotherboard. Network adapter cards are designed for a specific type of network,such as Ethernet, Token Ring, or FDDI. They operate at the Physical Layer ofthe OSI protocol stack.

A network adapter converts parallel bus data into serial data for transmissionover a wire.


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Before a successful data transmission can be accomplished, the sending andreceiving network adapter establish an electronic dialog and must agree onspecific criteria such as;

• the maximum size of data groups to be sent,• the amount of data to be sent before a confirmation,• the time interval between sending data groups,• the time interval to wait before confirmation is sent, and• how much data each NIC can hold before it “overflows.”

There are several methods used to increase the transmission rate of data fromthe network adapter card to the wire;

• Direct Memory Access – data moves directly from the network adaptercard to the CPU,

• Shared Adapter Memory – the computer will use the memory onboardthe network adapter,

• Shared System Memory – the network adapter card will use computermemory,

• Bus Mastering – network adapter card takes temporary control of thecomputer’s bus,

• Buffering RAM, and• Onboard Microprocessor - the network adapter does not rely on the

CPU.

Figure 16. Typical Network Adapter Card

Interrupt Request Lines (IRQ)Interrupt request lines are hardware lines over which devices can send interruptsor requests for service to the computer's central processing unit (i.e., CPU). Ifthe CPU is performing another task, the input, through the interrupt, allowsdevices to “get the attention” of the processor. Generally, IRQ settings must bespecific for each device in order to avoid a conflict. Therefore, when installing aNIC, it is important to locate a free IRQ setting (e.g., one that is not already in


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use). Most NICs are set to IRQ 5 since most computers on a network do nothave sound cards or second printers. Following is list of standard IRQ settingstypically found on most computers.

Table 6. Common IRQ Settings

IRQ DEVICE

1 Keyboard

2 Video (redirected IRQ 9)

3 Com 2, Com 4

4 Com 1, Com 3

5 Sound, LPT2, NIC

6 Floppy Disk Controller

7 LPT1

8 Real Time Clock (Reserved)

9 Redirected IRQ 2

10 Available

11 Available

12 Mouse

13 Co-Processor

14 HD Controller

15 Available

I/O Base Port AddressIn addition to IRQ settings, most devices will use a small portion of uppermemory to send and receive data from the CPU. The I/O base port specifies achannel through which information flows between the computer's hardware andits CPU. The port appears to the CPU as an address.

Each hardware device in a system must have a unique I/O base port numberaddress. The port numbers are in hexadecimal format. The most commonaddresses for NICs are 300 to 30F and 3l0 to 31F.

Hub (Repeater)Hubs are also referred to as repeaters. Repeaters regenerate signals forretransmission, and move packets from one physical media to another.Repeaters will pass broadcast storms; they do not perform any isolation ofpackets. Repeaters are used to extend the length of a network segment or toconnect different media types such as Ethernet Thicknet to Ethernet Thinnet.Repeaters cannot connect dissimilar media access methods together. Forexample, repeaters cannot connect a Token Ring segment to an Ethernetsegment. Repeaters amplify and regenerate signals to their original level andoperate at the Physical Layer of the OSI Model.


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Standard 10BaseT HubA standard 10BaseT hub is a typically an active (electrically powered) multi-portrepeater with RJ-45 connections. It connects multiple computers running10BaseT cable. The hub receives a signal from one computer (from itsrespective port) and sends the information to all the other connected ports. Allconnected devices must be running 10BaseT cable (Cat 3, 4, or 5) and 10BaseTnetwork adapter cards.

100BaseT Hub (Fast Hub)A fast hub works the similar to a 10BaseT hub, but supports networktransmission rates of 100Mbps. All connected devices must be running100BaseT Ethernet network adapter cards, Cat 5 cable, and use RJ-45connectors.

10/100BaseT HubA 10/100BaseT hub operates by combining the transmission speed capabilitiesof 10- and 100 Mbps. It includes the functionality of a 10BaseT hub, a 100BaseThub and utilizes a switch to translate between the two transmission speeds.Each port will switch between 10BaseT and 100BaseT as required by the deviceconnected to it. It does not provide the dedicated circuit of a switch, but it doesprovide a lower cost way to mix 10BaseT and 100BaseT on the same network.Note: The switch used in a 10/100BaseT hub is not to be confused with aSwitching Hub described in the following section.

BridgeBridges are used to segment networks; they forward packets based on addressof destination node. Bridges use RAM to build a routing table based onhardware addresses, and will connect dissimilar network topologies such asEthernet and Token Ring. Bridges will forward all protocols. Bridges are similarto repeaters in that they cannot distinguish protocols. Bridges also regeneratesignals at the packet level and over time learn the MAC address of devicesconnected to network segments. As the bridge learns its environment, it beginsto isolate packets to those network segments where the destination computerresides. Bridges forward all broadcasts to all attached segments.

SwitchesSwitches are hubs with bridging capabilities. Switches filter traffic through MACaddresses. Switches are used when upgrading to 100mb Fast Ethernet. Thepurpose of switching is to increase LAN performance by reducing the number ofworkstations on each LAN segment. The switch itself moves frames betweenports at very high speeds so it does not introduce any delay to the network. Thebest performance is achieved with one workstation per port so that there is nocontention at all when that workstation wants to transmit. The switch sets up aport connection between the sender and receiver for the duration of thetransmission.


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A switch, or switching hub, monitors the MAC address of each device connectedto it. When a computer sends a packet to a switch, the switch examines theMAC address of the destination computer. Rather than sending this packet to allcomputers, the switch will send this packet only to the computer where it isdestined to go. A switch greatly enhances communication bandwidth in anenvironment where packets are being sent between a lot of different computers.In an environment where all packets are going to or from a single machine (e.g.all workstations are sending to and receiving from a single file server) upgradingto a switch will not have a great effect.

10BaseT SwitchA 10BaseT switch is essentially a multi-port repeater that operates at a maximum10 Mbps. The difference between the repeater and the switch is based on thecapabilities of the port. The repeater will only pass on transmissions to all otherports, while the switch will send transmissions to a specific port.

10/100BaseT SwitchA 10/100 switch is similar to a 10BaseT switch, but each port can run at either10BaseT or 100BaseT transmission speed. Using a 10/100 switch you can takeadvantage of a 100BaseT connection to your file server while keeping 10BaseTconnections to your workstations. You can also use a 10/100 switch to migrateslowly from 10BaseT to 100BaseT.

RouterA router routes packets across multiple networks. Routers use RAM to build arouting table based on network addresses (i.e., IP address). A router sharesstatus and routing information to other routers to provide better trafficmanagement and bypass slow network connections. Routers are slower thanbridges due to complex functions. A router strips off Data Link Layer source anddestination addresses and then recreates them for packets. Routers canaccommodate multiple active paths between LAN segments. Routers will notforward non-routable protocols such as NetBEUI. Routers operate at theNetwork Layer of the OSI Model and function by disassembling packets. Onceopen, the router examines the packet for its desired destination address. Therouter then decides which port to forward the packet onto. Routers perform anexcellent job of isolating network traffic and limiting broadcasts. Like bridges,routers can also link unlike networks such as Ethernet and Token Ring.

GatewayGateways are highly complex devices used to link two or more networks withdifferent network architectures. For example, a gateway would provideconversion and translation from Ethernet to IBM's SNA architecture when a PCworkstation on a LAN needs to access an IBM mainframe, or when connectingNovell servers to Microsoft servers.


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I. Selecting the Appropriate LAN Protocol

A protocol is a set of rules and conventions for sending information over thenetwork. These rules govern the content, format, timing, sequencing, and errorcontrol of messages transmitted between network devices. A protocol can becompared to a language; just as two different people might use two differentlanguages to communicate through the same telephone hardware, a physicalnetwork can support more than one type of transport protocol. A networkoperating system, such as Microsoft Networking, may support more than onetype of transport protocol.

Multiple protocols may be bound to a single network adapter card. For example,a computer may utilize TCP/IP, NetBEUI, or IPX/SPX, and operate with onenetwork adapter. The order in which the protocol is bound determines the orderof use by the computer. For example, if IPX/SPX is bound first, IPX/SPX will beused to attempt to make a network connection. If the connection fails, thecomputer will transparently attempt to use the next protocol bound to the networkadapter card.

NetBEUI (NetBIOS Enhanced User Interface)NetBEUI is a simple network layer transport protocol developed to supportNetBIOS networks. NetBEUI is easily installed (self-configuring, and self-tuning),and requires low memory overhead. The disadvantages to using NetBEUIinclude its inability to transmit across a router, there is no support for crossplatform applications, NetBEUI can generate more traffic than other protocols,and it does not scale beyond small networks.

IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange)Novell NetWare servers and clients use this protocol. NWLink is the Microsoftimplementation of IPX/SPX. This protocol works well in both LAN and WANenvironments, and is routable. This protocol is usually required to access fileand print services on a Novell server. Until very recently it was the only protocolnatively supported by Novell NetWare. NetWare uses different frame types inconnection with protocol use. The frame type adhering to the standard 802.3was used as the default in NetWare 3.11. The frame type adhering to thestandard 802.2 was the default for subsequent releases of NetWare. Not allNetWare networks use the default frame type. If the frame type cannot bedetermined, many devices can automatically detect the frame type.

TCP/IP (Transmission Control Protocol/Internet Protocol)This protocol has become the defacto standard worldwide due to its popularity. Itworks well in both LAN and WAN environments, is routable, and is supported bymany operating systems and platforms. This protocol is required to access theInternet. Microsoft networking supports TCP/IP for Windows 95 and later clients,and for Windows NT. Every device on a TCP/IP network must have a subnetmask, and a unique IP address. If the device is located on a segmented


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network, a default gateway is also required. TCP/IP is supported by the latestversion of Novell NetWare (NetWare 5.0). Based on the worldwide use ofTCP/IP as a common protocol, additional discussion regarding TCP/IP ispresented in the foregoing section.

• TCP/IP is a standard communication language (i.e., protocol) usedextensively throughout the world. It is the predominant protocol utilizedon the Internet and in private networks (i.e., Intranet, Extranet).

• TCP and IP were developed by a Department of Defense (DoD)research project in order to connect a number of different networks(designed by different vendors) into a “network of networks.” Theproject was initially successful because it provided a few basic serviceseveryone needed, including file transfer, electronic mail and remotelogon. In December 1968, the Advanced Research Projects Agency(ARPA) awarded Bolt, Beranek and Bewman a contract to design anddeploy a packet switching network. The project was called ARPANETand four nodes were in place by the end of 1969; connections toEurope were established by 1973.

• The initial host-to-host communication protocol used in ARPANET wasthe Network Control Protocol (NCP). NCP soon proved to be unableto maintain the growing network traffic load, and subsequently, TCPand IP were proposed and implemented in 1974. These two protocolsprovided a more robust suite of communications protocols. TCP andIP have had numerous revisions with the most notable being IP version6, which was released in December 1995. In 1983, the DoD mandatedthat all of their computer systems would use the TCP/IP protocol suitefor wide area communications.

• TCP/IP is not a single protocol, but rather a suite of protocols. Severalof the protocols (e.g., TCP, IP, and UDP) provide "low-level" functionsnecessary for applications. Other protocols are necessary forconducting specific tasks (e.g., transferring files between computers,sending mail, or finding out who is logged in on another computer).These services should be present in any implementation of TCP/IP,except that micro-oriented implementations may not support computermail. These traditional applications still play an important role inTCP/IP-based networks.

• The core of the TCP/IP protocol suite consists of TCP, and IP.Together, these two protocols compose a two-layered program. Theupper layer (Transport) consists of TCP. TCP manages theassembling of a message or file into smaller packets that aretransmitted over the Internet and received by a TCP layer on the clientmachine that reassembles the packets into the original message. The


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lower layer (Internet) consists of IP. IP manages the address portionof each packet in connection with the destination. Each gatewaycomputer on the network checks this address to see where to forwardthe message. Even though some packets from the same message arerouted differently than others, the packets will be reassembled at thedestination machine.

• TCP/IP uses the client/server model of communication in which acomputer user (a client) requests and is provided a service (such assending a Web page) by another computer (a server) in the network.TCP/IP communication is primarily point-to-point; communication isfrom one point (or host computer) in the network to another point orhost computer

• Many Internet users are familiar with the even higher layer applicationprotocols that use TCP/IP to connect to the Internet. These include;Data Transfer Utilities (Hypertext Transfer Protocol [HTTP], FileTransfer Protocol [FTP], Trivial File Transfer Protocol [TFTP], andRemote Copy [RCP]); Remote Execution Utilities (Telnet, RemoteShell [RSH], and Remote Execution [REXEC]); and Printing Utilities;(Line Printer Daemon [LPD], Line Printer Requestor [LPR], and LinePrinter Queue [LPQ]). In addition, the Simple Mail Transfer Protocol(SMTP), and Simple Network Management Protocol (SNMP) areincluded with TCP/IP. These and other protocols are often packagedtogether with TCP/IP as a "suite."

• Personal computer connections to the Internet are usually through theSerial Line Internet Protocol (SLIP) or the Point-to-Point Protocol(PPP). These protocols encapsulate the IP packets in order to deliverthem over wide areas from a dial-up phone connection. To this end,PPP and SLIP may be considered WAN protocols while TCP/IP maybe considered a LAN protocol.

• Protocols related to TCP/IP include the User Datagram Protocol(UDP), which is used instead of TCP for special purposes. Otherprotocols are used by network host computers for exchanging routerinformation. These include the Internet Control Message Protocol(ICMP), the Interior Gateway Protocol (IGP), the Exterior GatewayProtocol (EGP), and the Border Gateway Protocol (BGP).


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Figure 17. TCP/IP Protocol Suite

OSI ModelProtocolsServices

TCP/IPProtocol

Layers

TelnetApplication

Presentation

Session

FTPTFTP

SMTP LPDLPRLPQ

RCPHTTP

SNMPREXECRSH

Application

Transport TCP UDP Transport

ICMP IGMPNetwork

ARP/RARPIP Internet

Data LinkLAN Technologies:

Ethernet, TokenRing, FDDI

WAN Technologies:Serial Lines Frame

Relay, ATMARPANet Network

Common TCP/IP Protocols by LayerTCP/IP represents a collection of network protocols, services, and utilities thatprovide services at the network and transport layers of the OSI Model. Theforegoing section presents the most common of these components organized bythe layer in which they are managed.

Application Layer: Provides the ability of one application to communicatewith another application independent of the hardwareplatform.

TELNET

• runs commands interactively in a terminal emulation application• uses TCP to achieve virtual connection between client and

server• ability to transfer binary data, emulate graphics terminals,

support macros• Allows a client to appear as a terminal directly attached to the

host (terminal emulation)• Text mode, menus, and command execution• Cannot download


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FTP• File Transfer Protocol• File transfer and directory access between client and host• copies files to/from a remote host reliably over TCP• cannot execute files• user level of authentication

TFTP• Trivial File Transfer Protocol• copies files to/from a remote host quickly over UDP• does not provide directory browsing• does not use user-level authentication

SMTP• Simple Mail Transfer Protocol• mail transfer

SNMP• Simple Network Management Protocol• allows diverse network objects to participate in a global network

management architecture• network management systems can poll network entities

implementing SNMP for information• network management systems learn of problems by receiving

traps from network devices implementing SNMP

Printing UtilitiesLPD

• Line Printer Daemon• responds to LPR/LPQ requests• sends print job data to the print device

LPR• Line Printer Requestor• submits a print job to a LPD server

LPQ• Line Printer Queue• queries the print job list of an LPD print server


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Data Transfer UtilitiesRCP

• Remote Copy• copies files to/from a remote host with no authentication

Web Browsers• Microsoft Internet Explorer and Netscape

Navigator/Communicator use HTTP (Hypertext TransferProtocol) to transfer pages of data from a Web server

Remote Execution UtilitiesREXEC

• Remote Execution• starts a process on the remote host• requires user account on TCP/IP host

RSH• Remote Shell• runs commands on a remote host• requires user name in “ .rhosts” file on UNIX host

Transport Layer: Communication sessions between computers.Error checking and acknowledgement.

TCP• Transmission Control Protocol• connection oriented: establishes a session before exchanging

data• reliable delivery: sequence numbers, acknowledgments• retransmits packets if error in transmission

UDP• User Data Protocol (UDP)• provides a simple but unreliable message service for

transaction-oriented services• connectionless: no session is established• does not guarantee delivery: no sequence numbers, no

acknowledgments


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Internet Layer: Encapsulation of data into packets, routingalgorithms.

IP• Internet Protocol• connectionless: no session is established• addresses and routes packets• does not guarantee delivery: no sequence numbers, no

acknowledgments

ARP/RARP/IARP• Address Resolution Protocol/Reverse Address Resolution

Protocol/Inverse Address Resolution Protocol/• successful mapping of an IP address to a hardware address• successful mapping of a hardware address to an IP address• address resolution is the function of ARP• uses local broadcast• address mappings are stored in cache for future reference

ICMP• Internet Control Message Protocol• Messaging on behalf of IP (e.g., “Destination host unreachable”)

IGMP• Internet Group Management Protocol• group membership advertisement

Network Layer: Putting packets on the wire and retrieving packets from thewire.

LAN Protocols• Ethernet, Token Ring, ARCnet, etc.• WAN Protocols: PPP, X.25, Frame Relay, etc.

IP AddressingIn order for a computer, workstation, device, or host to be identified on a network,it must have the following: 1) a unique physical address, 2) a name, or 3) an IPhost address.

The physical address is the MAC address that is hard-wired into the networkadapter card. The MAC address is used for LAN addressing, and notinternetwork addressing. The name is either a computer name (i.e., NetBIOSname), and/or a domain name (i.e., host name). Typically, the name provides arecognized identification for a host on an IP network. While users typically use aname, they must be resolved into an IP address. The resolution of an IP address


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into a NetBIOS name is accomplished by a Windows Internet Name Server(WINS), and the resolution of an IP address into a host name is accomplished bya Domain Name Server (DNS). The IP host address identifies a specific host onan IP network.

An IP address is a logical, numeric 32-bit binary number that contains two piecesof information: 1) the Network Identifier (i.e., group of computers), and 2) theHost Identifier (i.e., specific computer on the network. An IP address uses thedotted-decimal format similar to the foregoing example, where each periodseparates each byte of the 32-bit address: 192.168.100.200

The 32-bit address is broken down into 8-bit units called octets. There are fouroctets in an IP address. IP addresses are usually written in the form “w.x.y.z.”Each number w,x,y and z is a number within the range 0-255 which representsthe 8 bit value for that octet. Some values, particularly for w, are reserved andcan not be assigned.

Network NumbersConsider an IP address of the form w.x.y.z. The value of w determines thenetwork type of IP address.

Table 7. Network ID

VALUE OF W NETWORK CLASS NETWORK PORTION HOST PORTION

1-126 A w x.y.z128-191 B w.x y.z192-223 C w.x.y z

For example, an IP address of 34.x.y.z would be classified as a Class A address,and 221.x.y.z would be classified as a Class C address.

Table 8. Network Class

NETWORK CLASS AVAILABLE NETWORKS AVAILABLE HOSTS ON THE NETWORK

A 126 16,777,214B 16,384 65,534C 2,097,151 254

Unless you go through a gateway, you can only communicate with otherdevices that share your network number. Every device on an IP networkmust have a unique IP address. If your network is isolated, you canchoose network number any way you like. If your network is connected tothe Internet, you must obtain your network number from an IP addressingregistrar such as Network Solutions, Inc. Network Solutions, Inc., is anorganization that allocates network addresses to ensure that no twodevices have the same IP addresses.


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Subnet MaskingSubnet masks are used to subdivide an IP network. Technically, a subnet maskdoes not “mask” portions of the 32-bit octets, but uses those certain portions toidentify local or remote networks. There are default subnet masks for each classof networks.

Table 9. Default Subnet Mask

Network Class Value of w Default subnet maskA 1-126 255.0.0.0B 128-191 255.255.0.0C 192-223 255.255.255.0

Typically the default subnet masks are used for a given network unless thatnetwork has been subdivided into additional networks, also know as subnetting.A non-default subnet mask can identify a subnetted network. For example, aClass B network subdivided into six subnets would now have a subnet mask of255.255.224.0. Subnetting is used to create additional subnets (i.e., networks)and hosts per network.


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Figure 18. Network/Host ID

Class A Address

Network ID Host ID

W X Y Z

Example 124.14.211.85Default Subnet Mask = 255.0.0.0

Network ID = 124 Host ID = 14.211.85

Class B Address

Network ID Host ID

W X Y Z


Network ID = 131.14 Host ID = 211.85

Class C Address

Network ID Host ID

W X Y Z


Network ID = 206.14.211 Host ID = 85

DHCP (Dynamic Host Configuration Protocol)DHCP is a Session Layer protocol used to centralize IP address management oncomputers that are utilizing the DHCP server service. DHCP automaticallyassigns IP addresses to DHCP clients on a network. In addition, a DHCP server


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can automatically assign other components to a network client such as a subnetmask, default gateway, DNS and WINS server address.

If a LAN administrator chooses to implement a TCP/IP network, all of the clientmachines will require an IP address in order to access network resources. ALAN administrator may choose to manually assign an IP address to eachmachine or have a server (i.e., DHCP server) dynamically assign an IP addressto each client machine automatically. The latter case would be the preferredmethod in a situation where there are numerous computers on a network. Inorder to utilize DHCP, a DHCP server is configured with a scope (a block orrange of available IP addresses) and a machine on the network is configured asa DHCP client (recipient of a DHCP server).

When the DHCP server and client are configured correctly, the client machinewill log onto the network (with another protocol), and request an IP address fromthe DHCP server using a broadcast. The DHCP server will then issue an IPaddress to the client for a specified duration (i.e., lease) determined by the LANadministrator. After a four-step series of requesting, negotiating, assigning, andacknowledging, the client will obtain a valid IP address. The client will then beable to communicate over the network using TCP/IP services for the authorizedlease period.

Once a client machine has obtained a valid IP address from a DHCP server, theclient will request a renewal of that lease in two situations; 1) every time the clientlogs onto the network, and 2) at one-half the duration of the lease. In bothsituations, the client issues a request renewal via a directed send, rather than abroadcast, since it now possesses a connection oriented protocol.

GatewayEvery client using an IP address on a given network requires an IP address, anda subnet mask as minimum components for the protocol to function. A gatewayis used to forward IP packets from a host on one network, to a host on a differentnetwork. The gateway can be connected to multiple networks (an internetwork)and forwards the packets to the appropriate network.

J. Wide Area Networks (WAN)

A WAN establishes a connection between two or more remote locations overpublic and private data communication channels. Most WANs are acombinations of LANs and other of communications components connected bycommunication links called WAN links. WAN links can include the following;

• packet-switching networks• fiber-optic cable• microwave transmitters• satellite links• cable television coaxial cable systems


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Communication between LANs will involve one of the following transmissiontechnologies:

• analog• digital• packet switching

Digital communications include DDS, TI/T3, and switched 56. Since DDS utilizesdigital communication, it does not require modems. Instead, DDS sends datafrom a bridge or router through a device called a CSU/DSU (channel serviceunit/data service unit). This device converts the standard digital signals thecomputer generates into the type of digital signals (bipolar) that is part of thesynchronous communications environment.

T1/T3T- Carrier services transmit computer data and multiple voice channels overdigital trunk lines. The most common levels of T – Carrier service are T1 and T3.A T1 line supports data transmission rates of 1.544 Mbps, and a T3 line supportsdata transmission rates of 45 Mbps. T1/T3 lines are dedicated lines that aretypically leased or switched.

Packet switchingThe data package is broken into smaller packets and each package is taggedwith a destination address and additional identifying code. The packets arerelayed through stations in a computer network. The data paths for individualpackets depend on the best route at any given instant and use a virtual circuit -logical connection between the sending computer and the receiving computer

Switched 56Both local and long distance telephone companies offer this LAN-to-LAN digitaldial-up service that transmits data at 56 Kbps. Switched 56 is merely a circuit-switched version of a 56K bps DDS line. The advantage of switched 56 is that itis used on demand, thereby eliminating the cost of a dedicated line. Eachcomputer using the service must be equipped with a CSU/DSU that can dial upanother Switched 56 site.

Copper wire will accommodate T1 and T2. However T3 requires a high-frequency medium such as microwave or fiber-optic.

X.25X.25 is a set of protocols incorporated in a packet-switching network that usesswitches and circuits and routes data as available to provide the best routing atany particular time. This process uses telephone lines, and is slow due to theoverhead of error checking.


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Frame RelayFrame relay is a fast packet variable-length, digital, packet-switching technology.The process is point-to-point and uses permanent virtual circuits (PVCs) totransmit at Data Link Layer over a digital leased-line. This process requiresframe-relay capable routers or bridges.

ATMAn ATM (Asynchronous Transfer Mode) network is set up in a star configurationusing fiber-optic (and in some newer incarnations, twisted-pair) cables. Datatransmits at 155 Mbps and higher. A switch at the center of the star establishesa dedicated circuit between the sending and receiving stations. ATM is ideal forvideo, voice and teleconferencing applications.

ATM, however, requires new network adapters and, in most instances, fiber-opticcable connections. Furthermore, its implementations are limited and proprietary.Until ATM becomes more affordable and standardized, it is more cost-effective topurchase an Ethernet switch or Fast Ethernet to increase a network's bandwidth.

ISDNISDN (Integrated Services Digital Network) is an all-digital, circuit switchedcommunications systems. There are three implementations of ISDN; Basic Rate,Primary Rate, and Broadband-ISDN. Generically, three data channels are used;2 for 64kbps, and 1 for 16kbps. The 64kbps channels are known as B channelsand carry voice, data or image, and the 6kbps channel (i.e., D channel) carriessignaling and link management data. ISDN uses non-dedicated dial-up serviceand does not provide bandwidth on-demand as frame relay.

SONETSONET is a synchronous optical network that provides greater than 1 gigabit persecond transmission rate.

Modems (MOdulatos/DEModulator)Modems are electronic data communication devices that enable two systems tocommunicate over publicly switched telephone networks. The sending endmodem converts computer digital signals into analog signals that can betransmitted over the telephone lines. The receiving modem converts the analogsignal back into a digital signal that the computer can understand. There are twofundamental types of modems, asynchronous, and synchronous.

Asynchronous communications (Async)• use common phone lines• not synchronized, no clocking device• approximately 56,000bps• error control - a parity bit which is used in an error checking and

correction scheme called parity checking


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• signaling or channel speed - how fast the bits are encoded onto thecommunication channel

• throughputs - amount of useful information going across thechannel

• v.32bis, v.42, v.42bis

Synchronous communication• relies on a timing scheme coordinated between two devices to

separate groups of bits and transmit them in blocks known asframes

• if it detects an error, re-transmits it• format data into blocks• add control info• check the info to provide error control• the primary protocols in synchronous communication are:• synchronous data link control (SDLC)• high-level data link control (HDLC)• binary synchronous communication protocol• public dial network (bisync) lines (dial-up lines) - manually dial up to

make a connection• leased (dedicated) lines - full time connection that do not go

through a series of switches, 56kbps to 45mbps

K. Network Operating Systems – Microsoft/Novell Overview

MicrosoftMicrosoft networking environments are classified into two structures; Workgroupsand Domains. As previously discussed in Section II. (Networking Fundamentals– A Review), Workgroups are generally referred to as Peer-to-Peer, andDomains are generally referred to as Client/Server networks.

Windows NT domains require users to log on with a valid username andpassword. NT compares the username and password the user enters with thosein the user accounts database. If the names and passwords match, Windows NTauthenticates the user and logon is accomplished.

Windows NT can store the user accounts database locally, on the user'scomputer. These locally validated accounts are called workgroup accounts,because you can use the accounts to set up multiple NT computers in aworkgroup, or peer-to-peer, relationship. In this case, users log on to theirworkgroup computers.

Alternatively, Windows NT can check usernames and passwords against anaccount database located on a domain controller. For Windows NT to use adomain controller, you must first implement the NT domain model. In this model,


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Windows NT manages the accounts database from a central point, the PrimaryDomain Controller (PDC). In the domain model, the accounts are called domainaccounts, and users log on to the domain where they may have access todomain resources.

SMB (Server Message Block)SMB is a high level protocol (Application Layer) developed by Microsoft, Intel,and IBM. SMB defines a series of commands necessary to transmit informationbetween networked computers. The SMB protocol is used in the MicrosoftWindows and OS/2 NOS environments. In addition, CIFS (Common Internet FileSystem), which allows file sharing between computers over the Internet, is basedon SMB. SMB is also used in the Unix/Linux NOS environment in the form ofSAMBA.

SMB utilizes a redirector service that allows a client machine to locate files onother computers connected to the network using SMB (or SAMBA) and read,write, open, and execute those files. Once the redirector establishes the session,a two-way conversation occurs between the computers in which the followingtypes of SMB messages are exchanged:

• Session Control – Commands that start and end a redirector connection toshared resources at a server,

• File Messages – Used by the redirector to gain access to files at a server,• Printer Messages – Used by the redirector to send print jobs to shared

printers and capture information from print queues, and• Message Messages – Used to allow for the exchange of messages with

other machines on the network.

Novell - Introduction to NDSNovell networking environments use either Bindery or NetWare DirectoryServices (NDS) to organize network resources. Familiarity with NDS concepts isimportant when working within a Novell NetWare NDS environment.

NDS is a Directory Service. A Directory Service allows you to easily manageyour network resources. Simply put, the NDS Directory is a database of objectsthat represent network resources, such as network users, servers, printers, printqueues, and applications. The NDS Directory can be described as a hierarchicaltree.

The NDS Directory is stored as a set of database files on a server. A NetWareserver stores these files on volume SYS. If no file system volumes are present,the server stores the NDS database files in an NDS installation subdirectory.The NDS Directory can be replicated on multiple servers.


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The NDS TreeThe NDS tree can be thought of as a distributed database that containsdirectory information about objects. That is, the database contains objectsand the attributes, or properties, which describe those objects. Each NDStree maintains its own database of objects. Because it is a distributeddatabase, the database is usually contained on more than one server.

The information in an NDS tree does not describe the physical layout ofthe network. It usually describes the logical organization of the business.The NDS tree is usually organized into subtrees that reflect the differentdepartments and units in an organization. In turn, those subtrees containthe resources within the different departments.

Objects in the NDS TreeThe NDS tree is made up of objects. These objects represent networkentities and are of two basic types: Leaf Objects and Container Objects.In the tree representation, container objects can hold leaf objects andother container objects. Container objects are Country objects,Organization objects, or Organizational Unit objects. Leaf objects usuallyrepresent a network resource such as a user or a printer and can hold noother object.

Figure 19. NDS Tree With Objects


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If TOSHIBA used the Country Organizational Unit to organize its tree bycountry, the country organizational unit would be located between the rootand the Organization objects.

An object's name context is a list of these containers between the objectand [Root]. This context, or name, describes its position in the NDS tree.

Name ContextAn object's name context represents its position in the NDS tree. Thecontext is a list of containers separated by periods. This list of containerstraces the object's path back to [Root]. NDS locates an object by its pathfrom [Root]. For example, alpha.sc-class.sc1. Read this name as: alphais in sc-class, which is in sc1.

The following table defines the different ways NDS names are presented.

Table 10. NDS Name Types

NDS NAMETYPE

DESCRIPTION

CompleteName

An object's complete name is its object name combined with its context. Forexample, suppose a printer's object name is lpIII, and its context is eng.sc-class. The printer's complete name would be: lpIII.sc-class.sc1

Typeful Name Typeful names include the type of each object in the context (see below).

The object types use the definitions listed in Table 11.

Table 11. Object Types

OBJECT CLASS TYPE ABBREVIATION

Leaf objects Common Name CNOrganization Organization OOrganizational Unit Organizational Unit OUCountry Country C

The typeful name uses the type abbreviation, an equals sign, and theobject's name. For example, if Alpha were a user located in theTOSHIBA's HR department, his typeful name would be:CN=Alpha.OU=HR.O=TOSHIBA

The context helps you or the client agent locate a network resourcewithout knowing its network address. NDS looks up the resource'snetwork name or context and resolves it to a network address for you.


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Current contextThe current context is the context of the user's current workstation. Forexample, the context of a workstation in the Public Relations departmentcould be "pr.TOSHIBA".

Note that the user's object name is included in the current context. Thecurrent context is the location of the workstation only.

Relative Name and Periods

Relative nameNDS resolves relative names from the workstation's current context, notfrom [Root]. For example, if the workstation's current context is"pr.TOSHIBA", and the user's relative name is "joe.sales", NDS reads thename as joe in sales in the current context ("pr.TOSHIBA."). Never use aleading period with a relative name.

Leading and Trailing PeriodsLeading and trailing periods and relative naming relate to the currentcontext. Use a leading period when you want to resolve the name from[Root], regardless of the current context. For example, when NDS seesthe context ".pr.TOSHIBA." it will locate the PR container by walking thetree from [Root]. This is also called the absolute path.

You can only use trailing periods in relative naming. For each trailingperiod in a relative name, NDS resolves the name from one containercloser to [Root]. For example, if the workstation's current context is"eng.berlin.TOSHIBA" and you wanted to access Alpha's object in thecontext "hr.berlin.TOSHIBA" you could use the following string:"Alpha.hr.". NDS detects the trailing dot and removes the "eng"component from the default context before it appends the new context.So, the context will correctly read as: "Alpha.hr.berlin.TOSHIBA".

Each trailing dot removes one naming component from the defaultcontext. For example, to access Stan in sales in London, you can use thecontext: "stan.sales.London..". The NDS client detects the two trailingperiods and removes two name components from the default context,"eng.berlin.TOSHIBA" and changes the context to:"stan.sales.London.TOSHIBA.".

L. Network Administration

Certain concepts essential to network professionals (e.g., fault tolerance,data backup) will be addressed in the foregoing section only to the extentthat the student will be aware of that concept in a networking environment.These concepts do not directly apply to TOSHIBA connected products.


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Managing Network AccountManaging network accounts is the responsibility of the LAN Administrator.The following five management areas are essential to maintaining asecure and successful computer network;

• user administration• resource management• configuration management• performance management• maintenance

Managing Network PerformanceManaging network performance includes monitoring specific areas thatcould degrade the performance of a network. These areas include;

• bottlenecks (disk, memory, network, CPU)• one device using noticeable more CPU time than the others• view operations in both real time and recorded time for processors,

HDD, memory, network utilization, and network performance as awhole

• establish a baseline of system management• Simple Network Management Protocol (SNMP) - in a SNMP

environment, a program called agents are loaded onto eachmanaged device. The agents monitor network traffic and behaviorin key network components in order to gather statistical data. Thisdata is stored in a Management Information Base (MB).

• SNMP components include: hubs, servers, interface cards, routersand bridges

Back-UpEvery network should have a data backup policy. If the data is worthcreating, the data is worth saving. Several different methods are used tostructure a data backup policy, however, there are four fundamental typesused as a baseline for establishing the policy:

• Full Backup – backs up and marks selected files, whether or notthey have changed since last backup,

• Copy – backs up selected files without marking them as backed up,• Incremental Backup – backs up and marks selected files only if

they have changes since the last backup, and• Differential Backup - backs up selected files only if they have

changed since the last backup without marking them as backed up.


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UPSAn un-interruptable power supply may be used on a network in order toprovide;

• a power source to run the server for short duration,• safe shutdown of management service,• prevention of additional users from accessing the server,• alert messages to the network administrator, and• notification to users that the source power has returned.

Fault ToleranceA hard drive is susceptible to failure and could therefore produce dataloss. Protecting a computer from hard drive failure can be accomplishedby implementing a Redundant Array of Inexpensive Disks (RAID) system.RAID defines various techniques for combining multiple disk drives intoarrays. Upon implementation of a RAID system, the multiple drivesappear as a single drive to the system. A brief description of the mostcommon types of RAID follows:

• RAID Level 0 – Data is striped across several drives, but there is noredundancy of drives,

• RAID Level 1 – Data is striped into an array of drives and eachdrive is mirrored to a backup drive, known as Disk Mirroring

• RAID Level 2, 3, 4 – Data is striped to multiple disks, and parityinformation is generated and written to a unique parity disk,

• RAID Level 5 – Striping with parity - data is striped across multipledrives and then its parity sum is calculated, which is also stripedacross multiple drives.

M. Resolving Common Network Problems

Wrong IP AddressAn IP address that is a duplicate or that has the wrong network portion ofthe IP address will not work correctly. To view the configuration of theclient workstation, type “ipconfig /all” from the command prompt on aWindows NT client, or “winipcfg /all” from the DOS prompt on a Windows9x client.

Wrong Subnet MaskIf the wrong subnet mask is configured this will cause network problemsincluding addresses falling out of range or identified on local or remotenetworks.


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Wrong Default GatewayIf the wrong default gateway is entered, you will not be able to connect toservers on different networks. This has no affect on your ability to contactservers on your immediate network segments.

Wrong Frame TypeFrame type mismatch can prevent successful connectivity. Set the frametype explicitly if it is known, otherwise set the frame type to “auto.”

Account Locked OutAn account can be automatically locked out after several incorrect logonattempts (with the exception of the administrator account).

Logon RestrictionsA user is not allowed to logon if they attempt to logon during restrictedhours or from a restricted workstation.

N. Resolving Cable and Network Interface Card Problems

Open Connection on BusOpen connections occur most often when using Thinnet because thecable typically has many connectors and cables can be tugged as peoplemove or rearrange their workplace. An open bus manifests itself bycausing problems for every user on the segment. If you suspect an openconnection, go to the physical middle of the cable with two extraterminators. Open the cable segment and terminate both endstemporarily creating two segments. Check to see if one segment worksproperly. Keep "cutting" the failed network in half until you isolate theproblem.

Improper Termination and GroundingThe short chain found on terminators is to provide grounding. Note thatonly one end of the cable should be grounded. Grounding both ends cancause ground loops, which result in intermittent, difficult-to-isolate errors.

EMI (Electromagnetic Interference)Come from a variety of sources, such as improper cable insulation (e.g.,running data cable too close to air conditioning units), power generators,and even nearby radio stations. Look for recently added equipment, suchas air conditioners.

Driver Does Not Load SuccessfullyDrivers usually report an error if they fail to load properly. First, verify thatyou have the correct driver for your model of network interface card.Second, verify that the IRQ, Base I/O Port, Base memory, and DMAsettings are unique and are usable by the card.


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O. Resolving Printer Problems

Port SettingsIncorrect port settings will prevent a printer from accepting and processingprint jobs.

DriversPrint drivers must be compatible with the printer.

Novell PrintersNovell Print serversNovell QueuesThe settings for these objects must be compatible with the print device.

Microsoft TCP/IP Print ServicesLPRPort must have the correct IP address and port name and the port name iscase sensitive.


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II. NETWORK PRINTING – A REVIEW

A. Network Print Services

Network printers are connected in a wide variety of ways. In all cases, somemeans must be found to transfer the print job from the client, across the network,and to the server that is providing the print services.

Novell NetWare uses a combination of printing objects: a Print Queue Object, aPrinter Object, and a Print Server Object. The combination of settings for theseobjects determines how print services are provided to each print device.

Microsoft Windows networking provides for shared printers to be advertised as anetwork resource, available to any client with the appropriate permissions to usethat resource.

The Line Printer Requestor/Line Printer Daemon (LPR/LPD) protocols are twoprotocols that are part of the TCP/IP protocol suite. These protocols provideprinting services to many different types of systems that implement TCP/IPprotocol.

B. Novell NetWare Printing

ObjectsThe Print Queue Object, the Printer Object, and the Print Server Object providethe core functionality for network printing under Novell NetWare 3.x and NetWare4.x. The objects are used in the following ways:

Print Queue A Print Queue is basically a directory on the file server. Printjobs are stored inside the Print Queue on the file server untilthey are sent to the print device.

Printer In portions of Novell NetWare documentation, the Printerobject is described as the port driver. The printer object isresponsible for handling the details of getting data into theprinter. For example, if the printer is attached to a parallelport, the Printer will contain the LPT port number and theinterrupt used by that LPT port. The printer object can alsocontain a specification for a serial printer or some types ofnetwork attached printers.


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Print Server The Print Server monitors the status of the Print Queue. Atregular intervals, the Print Server will interrogate the fileserver to find out if there is a job in the Print Queue. If thereis a job in the Print Queue, the Print Server will remove itfrom the queue and arrange for the job to be sent to the printdevice, using the settings stored in the Printer object.

It is very important to distinguish between a Novell NetWare Print Server and thegeneric term print server. When used generically, the term print server describesa physical network device used to connect a printer to a network and provideprint services. When the term Print Server is used in Novell, it describes a logicalobject used as a part of the software system that provides print services. Thereis no corresponding term in NetWare to describe the physical device thatconnects the printer to the network.

C. Print Server Process

In addition to creating a Print Server object, there must be a print server processrunning on the network. Creating the Print Server object does not start a printserver process. It is similar to creating a user. When you create a user Jsmith,that action by itself does not log the user Jsmith into the network. But you mustcreate a user object for Jsmith before anything can log on to the network asJsmith. Similarly, creating the Print Server object does not actually start theprocess of monitoring the queue and sending jobs to the printer.

A print server process can be initiated by running PSERVER.NLM at the fileserver, running pserver.exe at a workstation or installing a third party applicationsomewhere on the network that provides this function. The actual print devicecan be physically connected to the system running the server process (a localprinter) or it can be located remotely on the network (a remote printer or networkprinter).

D. Windows Printing

Installing a Windows networked printer involves installing the printer locally andthen sharing the printer using Windows Networking. Once the printer is shared,other users can access the printer and print to it.

Installing the local printer typically involve using the Add Printer Wizard, althoughsome manufacturers will provide a custom installation instead. A local printer willoften be connected to a parallel port, although the manufacturer could also use aserial, SCSI or even network connection to the printer. In Windows, the term‘local printer’ means that the connection to the printer is managed at the localcomputer. It does not mean the printer is physically attached to the localcomputer.


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Once the local printer is functioning, it can be shared. In a peer-to-peer network,the access to the shared printer can be controlled with a password. If thenetwork is a Domain controlled by an NT Server and the printer is attached to acomputer running Windows NT, then access to the printer is managed usingaccess control lists from the domain security model. Users and groups can begiven access to the printer as desired.

A computer running Windows NT and sharing a printer can also share the driverfor the printer. It can share the Windows NT driver and it can also share theWindows 95 driver. This makes client installation easier, because the clients areautomatically provided with the driver.

Custom print devices are available that implement Windows networking. Thesedevices connect to the printer and share it on the network using Windowsnetworking. Such a printer is available on the network without dedicating asystem running Windows to the management of the printer.

E. LPR/LPD Printing

The Line Printer Requester (LPR) and Line Printer Daemon (LPD) protocols arepart of the TCP/IP protocol suite. LPD protocol is used to provide print serviceson the network and the LPR protocol is used to access network print services.To configure the LPR protocol, several items must be set:

• IP address of the LPD server or its domain name• Name of the print device on the LPD server• In some systems you may need a login name

Once this configuration is set up, the print job goes from the client running theLPR protocol to the server providing the LPD service.

LPR clients are available on a wide variety of systems. Most systems whereTCP/IP protocol is available will have an LPR client available. LPR clients areavailable for both NetWare and Windows NT. It is very common for a WindowsNT server to send print jobs to a network printer using LPR and then share thatprinter using Windows Networking.


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III. CONCLUSION

The Digital Connected Products Training Class, Network FundamentalsManual is intended to provide the student with a basic review of networkfundamentals, and network printing concepts. It would be prudent on the part ofthe student to review this document prior to attending the Electronic ImagingDivision training program. To this end, the student should feel free to reviewadditional resources regarding any areas covered in this review which wouldstrengthen his/her knowledge of a given topic.

With successful completion of the Instructor-led EID training program and thehelp of this Manual, you will become familiar with the installation andconfiguration of TOSHIBA digital connected products in a variety of networkenvironments. In addition, you should be able to support TOSHIBA digitalnetwork products with a high degree of confidence.


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IV. GLOSSARY

1-2-3The representative spreadsheet software developed by Lotus.

10Base2 (Thinnet Ethernet)see “Thinnet”

10BaseT (Twisted Pair Ethernet)Most widely used Ethernet connection; data travels at 10Mb/second.

100BaseT (Fast Ethernet)Fastest standard Ethernet connection; data travels at 100Mb/second.

32-bitRefers to number of bits used by an operating system to perform an operation. It is based on themicroprocessor that the OS is designed to run on.

-A -

AccessA database software for personal use developed by Microsoft. It can be used on the network by a group ofseveral users, and as the interface to use external data.

access methodTechnique for moving data between main storage and input/output devices. In a Systems NetworkArchitecture (SNA) environment, it is the software that controls the flow of information in a network.

accessibilityThe extent to which computers are easy to use and available to a wide range of users, including peoplewith disabilities.

adapterHardware installed in a PC or other computer and used to connect the computer to other hardware.

addressIdentifier assigned to networks, stations and other devices so that each device can be separately designatedto receive and reply to messages.

Address Resolution Protocol (ARP)Internet protocol that dynamically maps Internet addresses to physical (hardware) addresses on local areanetworks. ARP is limited to networks that support hardware broadcast.

Advanced Program-to-Program Communications (APPC)Part of the SNA protocol that establishes the conditions that enable programs to communicate across thenetwork. This capability, involving LU6.2 and its associated protocols, allows communication between twoor more processes in an SNA network without the involvement of a common host system or of terminalemulation.

advertisingProcess by which services on a network inform other devices on the network of their existence. TheNetWare network operating system (NOS) uses the Service Advertising Protocol (SAP) to do this.


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agentThe part of a networked system that performs information preparation and exchange on behalf of a softwareentity.

alarmAudible or visible warning signal that tells a network administrator that an error has occurred or there is acritical situation on the network.

alertSent by management devices to management consoles to inform administrators of thresholds reached anddiscrepancies on the network.

algorithmA prescribed set of well-defined rules or processes for arriving at a solution to a problem.

American National Standards Institute (ANSI)ANSI is responsible for the establishment of many standards, including a number of data communicationsand terminal standards. ANSI is the recognized U.S. representative within CCITT and ISO. See also CCITTrecommendations and International Organization for Standardization.

analogData in the form of some continuously variable physical quantity. For a communications signal, acontinuously variable waveform (as opposed to discretely variable). The public telephone network wasdesigned to transmit voice messages in analog form. Contrast with digital.

ANSI CThe standardized C programming language.

AIAUI (Apple AUI)Interface designed by Apple Computer, Inc. for the connection of a transceiver to a Macintosh equipped withbuilt-in Ethernet.

AppleShareAppleShare is Apple Computer's networking solution. It requires a Macintosh computer as a network serverand includes both server and workstation software. It uses the AppleTalk Filing Protocol (AFP). Novell'sMacintosh connectivity solution teams NetWare for Macintosh server software with AppleShare workstationsoftware.

Apple TalkA protocol for the Macintosh computer structuring a network using Ethernet or the token-ring system. Itrequires network adapters, while Local Talk does not.

AppleTalk Filing Protocol (AFP)Allows distributed file sharing across an AppleTalk network.

applicationA software program or program package that makes calls to the operating system and manipulates datafiles, thus allowing a user to perform a specific job (such as accounting or word processing).

application binary interface (ABI)A specification defining the interface between an operating system and a certain hardware platform,particularly the calls between applications and the operating system.

application interfaceA set of software routines and associated conventions that permits application programmers to use thatinterface as a part of any application. In general, an application interface is used to access system ornetworking services that would otherwise require significant development effort to create from scratch. Forexample, the ManageWise application interface lets a programmer use ManageWise file structures andservices within an application. See also application programming interface.


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Application Programming Interface (API)A means by which an application gains access to system resources, usually for the purpose ofcommunication (the sending and receiving of data), data retrieval or other system services. In the specificarea of terminal emulation, an API provides for the simulation of keystrokes and for writing into and readingfrom the presentation space (device buffer). It may also provide for the sending and receiving of structuredfields.

application serverA server in a client-server network which runs one or more applications that can be shared by client stationsand which also shares the data processing burden with client stations. This shared application and shareddata processing model contrasts with the model used for other servers, such as file servers, that simplysend, receive, and store files, requiring client stations to run all applications and process all data. Eithermodel can be most advantageous, depending on circumstances. In many circumstances the applicationserver model allows for faster data processing, faster throughput to client stations, greater data reliability,and increased data security.

architectureA terminology indicating the mechanism of computer such as what parts and what OS the computer uses,and how their functions are related to operate the computer.

archiveTo create a redundant copy of computer file data, typically to create a backup copy of that data to protect itif the original copy is damaged or otherwise irretrievable. By some definitions, an archive is required tocontain copies of every version of a particular file. In this case, to archive means to save a copy of everyobject in a file system with aseparate copy of all changes made to that file. In addition to protecting files from loss, this approach alsopermits any previous version of a file to be restored, typically by date and time.

AS/400An IBM minicomputer.

ASCIIAcronym for American Standard Code for Information Interchange, a 7-bit code that is the U.S. nationalvariant of IS 646.

Asynchronous Transfer Mode (ATM)A new exchange system standardized by ITU-T for transferring multimedia data on wide area networks. Ithas advantages of both the line switching and packet switching systems. It can flexibly change the transferspeed using 53-byte cells.

asynchronousA data transmission in which the transmission of a character or a block of characters can begin at any timebut in which the bits that represent that character or block have equal time duration. See also synchronous.

ATCONDiagnostic tool used in Novell NetWare environments; provides information about a server or router'sAppleTalk stack, and about other AppleTalk networks on the internetwork.

attachTo access a network server; particularly to access additional servers after logging in to one server.

Attached Resource Computing Network (ARCnet)A proprietary token-bus networking architecture developed by Datapoint Corporation in the mid-1970s.Currently, ARCnet is widely licensed by third-party vendors and was a popular networking architecture,especially in smaller installations. It has a bandwidth of 2.5 Mbit/s, is reliable, and supports coaxial, twistedpair and fiber optic cable-based implementations.

Attachment Unit Interface (AUI)Interface using a DB-1 5 plug that allows the connection of an external transceiver.


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attributesA technique for describing access to and properties of files and directories within a filing system. ForNetWare files, attributes include Read, Write, Create, Delete and Execute Only (prevents files from beingdeleted or copied). For NetWare directories, attributes include Read, Write, Create, Execute and Hidden(hides information about the directory from file listings, preventing unauthorized access, deletion or copying).

autoauthenticationIn a client-server environment, a utility that lets users access unrestricted network resources withoutpassword verification. Only when a user attempts to access a restricted resource does the utility prompt fora password.

autologinIn a network environment, a utility that regulates user login attempts.

automountA graphical utility that provides an iconical tree structure to simplify the user's task of locating and using aserver, file system, or volume.

- B -

backbone networkPrimary connectivity mechanism of a hierarchical, distributed network. Ensures that all systems that haveconnectivity to an intermediate system on the backbone have connectivity to one another.

Backup Domain Controller (BDC)A preliminary domain controller preparing for the case of PDC (primary domain controller)

bad block tableA list kept on a hard disk of storage locations on the disk that are damaged or physically unable to hold datareliably. Also called "media defect list."

bandingVisible stair-stepping of shades in a gradient eliminated by true Adobe PostScript.

bandwidthCarrying capacity of a circuit, usually measured in bits per second for digital circuits, or hertz for analogcircuits.

basebandNetwork technology that uses a single carrier frequency and requires that all stations attached to a networkparticipate in every transmission.

basic input/output system (BIOS)A set of programs, usually in firmware, that enables each computer's central processing unit to communicatewith printers, disks, keyboards, consoles and other attached input and output devices.

beaconingIn token-ring networks, the state that results when an error condition occurs, preventing communication untilthe error condition is resolved.

Berkeley Software Distribution (BSD)A UNIX operating system version developed at the University of California, Berkeley.

beta testDistributed pre-release software sent to selected users and customers in order to get feedback and filebug reports.

binaryNumbering system using only zeros and ones.


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binary fileA file that has been encrypted, encoded, or compiled, as opposed to a plain textfile.

binderyA network database, in versions of the NetWare network operating system earlier than 4.0, that containsdefinitions for entities such as users, groups, and workgroups.

bitBinary digit; either a one or a zero.

bit/sThe rate at which data is transferred over a serial interface.

bitmapDescribes pixel oriented displays and the number of bits (which can each hold a color) included in eachpixel. 1 bit is black and white. 8 bit is gray scale and 16 or 24 bits is full color.

bitmap fontA font whose characters are represented by bitmaps or by a pattern of dots, as opposed to a TrueTypefont, whose characters are represented by lines and curves. A bitmap font is generally less scaleableand more jagged than a TrueType font.blockSet of continuous bits or bytes that make up a definable quantity of information such as a message.

boundaryThe point of interaction between systems or applications that use different character encoding.

bridgeConnects two or more network segments together so that equipment on the network can communicate.

British Naval Connector (BNC)British Naval Connector is a twist-lock connector used to attach coax cables to computers.

broadbandCharacteristic of any network that multiplexes multiple, independent network carriers on a single cable.Allows several networks to coexist on a single cable. Traffic from one network does not interfere with trafficfrom another network because conversations happen on different frequencies.

broadcastPacket delivery service in which all nodes on a network receive a copy of any frame that is designated forbroadcast or, when used as a verb, sending the message to all nodes.

brouterA device having functions of both a bridge and a router. It performs as a bridge or a router depending onprotocols.

bufferMemory area or electronic register where data is stored temporarily while awaiting disposition. Itcompensates for differences in data-flow rates (for example, between a terminal and its transmission line).Also used as a data backup mechanism, holding data that may be retransmitted if an error is detectedduring transmission.

burstMethod of data transfer in which information is collected and sent as a large unit in one high-speedtransmission. LAN traffic is usually considered bursty traffic because it has short intervals of intense activitywith lulls between.

bus topologyThe cable in a bus topology is linear with two definite endpoints. Computers attach at various points alongthe cable. Each end of the bus must be properly terminated to avoid signal reflections.


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byteOne byte equals eight bits. Byte is a standard unit of measurement for file size and is often referenced askilobyte, megabyte, gigabyte, terabyte.

- C -cacheHigh-speed memory section that holds blocks of data that the CPU is currently working on; designed tominimize the time the CPU spends accessing memory.

calibrationSetting equipment to a standard measure to produce reliable results - essential for quality digital colorprinting.

carrier waveSignals carrying data in the broadband system.

caseThe capitalized (uppercase) or non-capitalized (lowercase) form of an alphabetic character.

CCITT recommendationsThe CCITT is a committee that recommends standards for communications equipment interfaces,communications protocols, modem modulation methods and so on.

cc:MailAn electronic mail software by Lotus.

Central Processing Unit (CPU)Refers to the brains of a computer. On a network it is known as a node.

Challenge Handshake Authentication Protocol (CHAP)A security protocol for user authentication for PPP circuit of the Internet.

Channel Service Unit (CSU)Digital signal processor that performs transmit and receive filtering, signal shaping, longitudinal balance,voltage isolation, equalization, and remote loopback testing for digital transmission. It functions as aguaranteed safe electrical circuit, acting as a buffer between the customer's equipment and a public carrier'swide area network. CSUs prevent malfunctioning digital service units (DSUs) or other customer premisesequipment from disabling a public carrier's transmission system. The design of a CSU must be certified bythe FCC.

characterGroup of eight binary digits operated on as a unit; also called a byte or octet.

client/serverNetwork that is designed with centralized machines that provide connectivity of file and print sharingservices. A client is a computer connected to a shared network or server.

clientNode or workstation (computer) on a computer network that requests services from a network server. Clientstations run client software. An executing software program or set of programs through which a clientstation sends a request to a server and waits for a response (for example, the NetWare Client for DOS/MSWindows). The user end of a client-server connection.

client-server modelData communication model that relies on distributed, intelligent interaction between network servers andindividual (client) workstations. Clients request services from servers. Servers receive client requests andreturn requested data or results. Clients and servers may be any class of computer, but often the client is adesktop computer and servers are powerful microcomputers, "workstation class" computers orminicomputers. Data communication model in which there is (1) server software that starts execution beforecommunication begins and, after communication begins, continually accepts requests from and returns


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responses to clients, and (2) client software that periodically sends requests for services to the server andaccepts server responses.

client-server networkA network consisting of client nodes (workstations) which have client capabilities only and server nodeswhich have (usually) server capabilities only. On a client-server network, communication and data sharingbetween clients is, in most cases, arbitrated by the network servers. Each client runs client software andeach server runs a client-server operating system (see client-server operating system below). A simpleNetWare network with only one server, a file server, is a classic example of a client-server network.

client-server operating systemAn operating system which runs on a server in a client-server network and which is responsible forcoordinating the use (by clients) of all resources available from that server. Server resources includehardware such as hard disks, Random Access Memory (RAM), printers and equipment used for remotecommunications, such as modems.Resources also include logical systems such as the network file system and network directory services, andthe information (data) therein. The NetWare 3 and 4 operating systems are client-server operating systems.

clipboardA Windows utility used as a buffer for copying and pasting text and other material.

clock speedThe speed in terms of computing power of a CPU (expressed in Megahertz)

CMYK (Cyan, Magenta, Yellow, and Black)Colors used in four-color process printing.

coaxialAlso known as “coax.” This cable carries its signal on a central wire. This wire is surrounded by aninsulator and a second conductor which “shields” the inner conductor from unwanted electrical signals.

collisionWhat happens when two devices transmit data at the same time, resulting in a loss of data.

Color Rendering Dictionaries (CRDs)Converts PostScript RGB files to the copier’s CMYK space.

color separationSeparation of a color image into four process colors, cyan, magenta, yellow & black (CMYK); when layeredon an offset press or color copier, they combine to create continuous tone color.

Commission lnternationale de l’Eclairage CIE)International committee that developed set of color definition standards.

common dialogsStandard dialog boxes defined by Windows, such as Open, Save As, Print, and Find, that are used foroperations in numerous applications. Applications can call common dialog API functions directlyinstead of having to supply a custom dialog template and dialog procedure.

Compact Disk-Read Only Memory (CD-ROM)A CD-ROM is played on a computer through a CD-ROM drive. The computer runs information stored on theCD-ROM. One CD can store 640 megabytes of data and media.

compressionA system which uses algorithms to create smaller file sizes of stored images. Lossy compression usesaverages and changes the nature of the image while Lossless compression maintains the exact structure ofthe image.

configurationThe way in which a system or part of a system, such as a piece of software, is set up, based on a number ofpossible choices.


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configuration managementRefers to the management of networked applications and their related user access.

consoleThe Windows subsystem that runs character-based applications, as opposed to applications that have agraphical user interface (GUI).

constantA numeric value, typically an integer, that refers to a character value, the size of a buffer, the position ofa character in a string, and so forth. It is assumed that the value does not change during the time aprogram is running.

contentionOne of the systems for transmission. The right to send data is given to users on a first-come-first-servedbasis.

control panelA group of Windows utilities used to edit system settings, including international preferences.

concentratorDevice with a single bus and multiple connections to computers; provides a star-wired physical layout.

connectionlessModel of interconnection in which communication takes place without first establishing a connection.

Connectionless Network Protocol (CLNP)Open Systems Interconnection (OSI) protocol that provides the OSI Connectionless Network Service(delivery of data). CLNP is the OSI equivalent of the NetWare IPX protocol and the Internet IP protocol.

Connectionless Transport Protocol (CLTP)Provides end-to-end transport data addressing and error detection, but does not guarantee delivery orprovide flow control. The Open Systems Interconnection (OSI) equivalent of the User Datagram Protocol(UDP) datagram service.

connection-orientedModel of interconnection in which communication proceeds through three well-defined phases: connectionestablishment, data transfer, and connection release.

connectivityThe ability to connect to and communicate with multiple architectures on a single network.

consoleThe monitor and keyboard from which you actually view and control server or host activity.

Copper Distributed Data Interface (CDDI)The identical cable system as FDDI, except that CDDI uses twist-pair cable as a medium.

cross-platformPortable to more than one operating system.

crosstalkUndesired voices of people other than those using the telephone line. The same thing happens in datatransmission which causes errors. Twisted-pair cable is resistant to cross-talk.

CSMA/CACarrier Sense Multiple Access/Collision Avoidance is another mechanism used to determine when acomputer could transmit data. Computers CSMA/CA will evaluate whether data was successfullytransmitted by waiting for an acknowledgement from the recipient.

CSMA/CD


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Carrier Sense Multiple Access/Collision Detect is another mechanism used to determine when a computercould transmit data. Computers must wait for a “quiet” line before they begin transmitting data. Then they“listen” for data collisions with other computers.

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dataData is an entity that conveys meaning. Computer data is stored as a series of (electrical) charges arrangedin patterns to represent information. In other words, data refers to the form of the information (the electricalpatterns). It is not the information itself.

databaseA collection of data with a given structure for accepting, storing and providing data for single or multipleusers.

data compression devicesEquipment that compresses data into a smaller number of bits, allowing more data to be transmitted persecond than the link speed otherwise allows.

Data Encryption Standard (DES)A standard encryption technique that scrambles data into a code for transmission over a public network.

datagramOne packet of information and associated delivery information that is routed through a packet-switchingnetwork.

data rateSpeed at which data bits are transmitted and received. Usually measured in bits per second (bit/s).

DECnetA set of networking protocols developed by Digital Equipment Corporation and used in its VAX family ofcomputers to exchange messages and other data. Although DECnet is currently a proprietary protocol,DEC is merging its protocols with OSI protocols for the upcoming DECnet Phase V. When this process iscomplete, DECnet protocols should interoperate with any OSI-compliant network node.

decryptionUnscrambling or decoding of encrypted data.

dedicatedA device that has only one function. For example, a dedicated server cannot be used as a workstation.

dedicated lineLeased or private communications line.

demodulationProcess of recovering information from a previously modulated carrier frequency by converting analogsignals into digital signals.

densitometerDevice used in calibration used to measure toner density of a copier and help users control the accuracy,quality and consistency of output.

Desktop Color Separation (DCS)Document format which comprises four digital separation files (CMYK) with a composite preview file suitablefor display on a computer monitor or low-resolution printer.

desktop computerA small-scale computer that fits on a desktop and that has a microprocessor system. Also called amicrocomputer or personal computer. Contrast with minicomputer and mainframe computer.


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developerOne who develops software, either for internal use or for commercial sale.

device driverSoftware or firmware that translates operating system requests (such as input/output requests) into a formatthat is recognizable by specific hardware, such as adapters.

dial-up lineCommunications line accessible via dial-up facilities, typically the public telephone network.

digitalRepresentation of information using ones and zeros. It is discretely variable as opposed to continuouslyvariable. Data characters are coded in discrete separate, electrical pulses or signal levels. Contrast withanalog.

Digital Service Unit (DSU)A data circuit-terminating equipment required to use ISDN. It converts the digital signals of data terminalequipment (such as personal computers) to digital signals used on digital transmission circuits.

directory cachingNetWare feature to improve performance. In directory caching, copies of the file allocation table and thedirectory entry table are written into the network server's memory. A file's location can then be read frommemory, which is faster than reading it from a disk.

directory hashingNetWare feature to improve performance. Directory hashing is a method of indexing file locations on a diskso the time needed to locate a file is reduced.

directory rightsRestrictions specific to a particular directory.

directory servicesNetwork service that provides information about an entity of interest. It is similar to an electronic phone bookto help network clients find services. There are several designs, including the X.500 standard, the DomainName System and Novell's NetWare Directory Services.

directory structure duplicationNetWare feature that protects data from failures in network hardware. A hard disk's directory and fileallocation tables contain the address information the operating system needs to determine where to store orretrieve data. To reduce the possibility of losing this information, the NetWare network operating system(NOS) maintains duplicatecopies of both the directory table and the file allocation table on separate areas of the hard disk. If theprimary copy is lost or destroyed, the NetWare NOS uses the secondary copy.

directory verificationNetWare feature that protects data from failures in network hardware. Each time the server is turned on, theNetWare network operating system performs a consistency check on duplicate sets of directory and fileallocation tables to verify that the two copies are identical.

disk arrayA system of having multiple disks for parallel usage to prevent the loss of data, and accelerate the speed ofreading and writing data in hard disks.

disk duplexingFeature that protects data from failures in network hardware. In disk duplexing, all data on one hard disk isduplicated on a second hard disk on a separate channel. Disk writes made to the original disk are alsomade to the second disk. If the original disk or channel fails, the duplicate disk takes over automatically.


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disk mirroringFeature that protects data from failures in network hardware. In disk mirroring, all data on one hard disk isduplicated on a second hard disk on the same channel. Disk writes to the original hard disk are also writtento the second hard disk. If the original disk fails, the duplicate disk takes over automatically.

Disk Operating System (DOS)The disk operating system (DOS) is the software that organizes how an IBM-compatible computer reads,writes and reacts with its disks and communicates with various input/output devices. The most commonversions are DR DOS, MS-DOS and PC DOS.

distributed applicationAn application that operates in a distributed computing environment, where application modules may run ondifferent systems.

distributed computingA computer operating environment that may involve computers of differing architectures and datarepresentation formats that share data and system resources.

distributed networkA computer network on which processing is shared by many different parts of the network. Processing maybe shared by client (local) computers, file servers, print servers and application servers such as databaseservers. Distributed processing enables the most efficient use of processing power because availableprocessors can be dynamically assigned as either general or job specific processors, depending on the typeof work to be done and the existing work load. Distributed processing also enables duplication anddistribution of key services, such as directory services, so that full services remain available regardless ofthe failure of individual parts of the network.

distributed processingA technique to enable multiple computers to cooperate in the completion of tasks, typically in a networkedenvironment. Each computer that contributes to the completion of the total task actually does so bycompleting one or more individual subtasks independently of its peers, reporting the results from itssubtasks as they arecompleted.

domainIn the Internet, a part of a naming hierarchy. Syntactically, an Internet domain name consists of a sequenceof names separated by periods. In the NetWare network operating system and OSI, it is generally used asan administrative partition of a complex distributed system.

Domain Name System (DNS)Distributed name/address database used on the Internet.

DOMINOA Web server software by Lotus. It can distribute the data of Notes, and write in Notes database.

Dot GainAmount by which a half-tone dot grows between the film, the plate, and the press sheet - an inevitable partof the printing process.

Dots Per Inch (DPI)A measure of the output resolution produced by laser printers or image setters.

downtimeTime when a system or network is unavailable.

drag-and-drop functionA mouse pointer operation in which you select an object and place it in a new location. For example, to printa document, you drag its icon to the printer icon and drop it there.


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driverA software program that allows a computer to communicate with other equipment; the driver manipulateshardware in order to translate data to the equipment.

dumb terminalSimple CRT and keyboard with limited capabilities such as display and edit functions.

Dynamic Host Configuration Protocol (DHCP)A protocol which automatically assigns an IP address to a personal computer newly connected to thenetwork.

Dynamic-Link Library (DLL)A module containing functions that other programs or DLLs can call. DLLs cannot run by themselves;they must be loaded by other programs.

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e-mail (electronic mail)A method of file transfer and message sending among workstations.

Encapsulated PostScript (EPS)File format used to transfer PostScript image information from one computer software program to another.

encoding A system of assigning numeric values to characters.

encryptionScrambling or coding of data for security.

engineThe core of a database or of an application.

error detectionProcess of determining whether one or more bits have changed from a one to a zero, or vice versa, duringtransmission.

EthernetA network cable and access protocol scheme originally developed by DEC, Intel and Xerox. It has abandwidth of 10 Mbit/s and supports coaxial, twisted pair (10Base-T) and fiber optic cable implementations.

EtherTalkAppleTalk packets encapsulated to run on Ethernet cables.

ExchangeA groupware by Microsoft. It includes the mail function, scheduler, meeting room manager for reservation,etc.

ExcelA spreadsheet software developed by Microsoft. It was originally developed for Macintosh computers, but itis now widely used as the spreadsheet software for Windows.

expansion cards or boardsCircuit boards that fit into internal computer expansion slots and control specific functions such asnetworking sound, video and modem.

expansion slotsSlots inside the computer that allow one to expand the computer’s capabilities.

Extended Binary Coded Decimal Interchange Code (EBCDIC)Eight-bit code defined by IBM. Includes values for control functions and graphics.


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Fax ModemA type of modem having the function to fax documents directly from personal computers that are preparedby a word processing program, etc. It also has the function to import faxed documents to personalcomputers as data.

FCONSOLENetWare 3 utility used to access information from the network server and fine-tune its performance. It is avirtual console utility that allows the operator to control a server from any station on the network.

Fiber Distributed Data Interface (FDDI)Token Ring LAN technology that is optical fiber based and supports data transfer rates up to 100 MB/sec.

fiber-optic cableHigh-bandwidth transmission medium that allows data to be transmitted by modulating a light wave througha special glass or plastic fiber.

file allocation table (FAT)A FAT keeps track of file locations in a particular volume. The NetWare network operating system (NOS)divides each volume into blocks and stores files on the volume in these blocks. If the file consists of one ormore blocks, the file may be stored in blocks that are not adjacent. The FAT keeps track of the blocknumbers where differentparts of the file are located. To retrieve a file, the NetWare NOS searches through the FAT until it finds theFAT entries and corresponding block numbers for the requested file.

file sharingAn important feature of networking that allows more than one user to access the same file at the same time.

File Transfer, Access, and Management (FTAM)The Open System Interconnection (OSI) remote file service and protocol.

fire wallExisting between Internet and a LAN to let LAN access to Internet, and intervene access from Internet toLAN. It is realized by using a software on server machines.

firmwareSet of software instructions that are set, permanently or semi-permanently, into integrated circuitry.

flow controlA rule to regulate the transmission volume of data. It prevents from failing to receive to data on thecomputer with less capacity when transmission is performed between computers of different capacities.

fontAny of numerous sets of graphical representations of characters that can be installed on a computer orprinter.

font associationThe automatic pairing of a font that contains ideographs with a font that does not contain ideographs.This allows the user to enter ideographic characters regardless of which font is selected.

frame bufferPortion of computer memory that contains a pixel-by-pixel description of a page in digital form.

Frame RelayThe frame relay method is a protocol on the simplified data link layer. It is the method that frame control orerror detection are not performed, and these functions are to be performed by the higher ranked protocols.


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frequencyA unit which is the number of times a wave vibrates per second. Modems use two kinds of frequency, andconvert analog signals to digital signals by changing higher analog signals to 0 and lower analog signals to1.

full-width characterIn a double-byte character seta character that is represented by 2 bytes and typically has a half-widthvariant.

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gammaMeasure of contrast affecting the midtones of an image.

gamutRange of colors

gatewayA hardware/software package that runs on the OSI application layer and allows incompatible protocols tocommunicate; includes X.25 gateways. Usually connects PCs to a host machine, such as an IBMmainframe.

Gigabit EthernetEmerging Ethernet standard for increased network bandwidth to 1 Gigabit per second.

gigabyte (GB)A unit of measure for memory or disk storage capacity. Two to the 30th power (approximately one billion)bytes.

Graphical User Interface (GUI)A system which can be easily operated by using mouse pointing on icons of applications, files, andcommands like Mac or Windows.

Gray Component Replacement (GCR)Technique for replacing all the neutral tones of an image with an appropriate amount of black.

grayscaleA continuous tone image made up of a number of shades of gray.

groupwareA type of software that supports concurrent use of objects (such as documents, calendars andspreadsheets) by multiple LAN users.

GroupWiseA groupware by Novell. The scheduler is the strong point of GroupWise.

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half-duplex communicationA method of communication that enables both the communicating points to send data but only one way at atime.

halftone screenPattern of dots of different sizes used to simulate a continuous tone photograph either in color or black andwhite.

half-width characterIn a double-byte character set a character that is represented by one byte and typically has a full-widthvariant.


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hard-codingPutting string or character literals in the main body of code, such as .C or .H files, instead of in Windowsresource files. Basing numeric constants on the assumed length of a string.

hard disk driveA computer device consisting of one or more disks used to store information.

hardwareComponents of a computer system including monitors, hard drives, CD-ROM5, printers keyboards, amouse, portable hard drives, modems, etc.

Hierarchical File System (HFS)Attached to AFP in the Macintosh operating system. It manages files and directories.

High-Level Data Link Control (HDLC)Communications protocol defined for high-level, synchronous connections to X.25 packet networks. Similarin almost all respects to SDLC.

High-Level Language/Application Program Interface (HLLAPI)Application programming interface designed for use with high-level languages.

hop numberIt indicates the number of the routers passed when the data transmitted from the sender to the receiver.

hostA computer that is attached to a network and provides services to another computer beyond simply storingand forwarding information. Usually refers to mainframe and minicomputers.

hot fixNetWare feature that protects data from failures in network hardware. When the Hot Fix feature is activated,a small portion of a hard disk's storage space is set aside as a Hot Fix redirection area. When read-after-write verification determines that there is a bad data block on the disk, Hot Fix redirects data that was to bestored in the bad block to the Hot Fix redirection area. Hot Fix marks the defective block as bad, and theserver will not attempt to store data there again.

hubReceives and sends signals along the network between the nodes (computers) that connect to it. In a LAN,a hub is the core of an Ethernet Star network.

hueMain attribute of a color which distinguishes it from other colors.

hypertextA method for storing, retrieving and presenting information based on the processing power of computers.Allows computerized linking and almost instantaneous retrieval of information based on a dynamic index.Hyper Text Transfer Protocol (HTTP)A protocol used for WWW clients to communicate with servers.

- I -

image setterComputer-controlled device used to output images at high resolution onto photographic paper or film.

Integrated Services Digital Network (ISDN)A public telecommunication network announced by CCITT in 1980. The telephone, telegraph, telex, data,facsimile, and videotex are integrated and transmitted as digital signals on the same network. In Japan, NTTprovides this service as INS NET.

intelligent hubUnit combining the function of a hub with processing capabilities.


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interfacePoint at which a connection is made between two elements so that they can work together.

Interior Gateway Routing Protocol (IGRP)A protocol for routers by CiscoSystems. It uses various information called merit information when it choosesa route.

International Organization for Standardization (ISO)Based in Paris, this organization develops standards for international and national data communications.

InternetCollection of networks and gateways that use the TCP/IP suite of protocols. Lowercase, it is an abbreviationfor internetwork.

Internet Control Message Protocol (ICMP)An Internet control protocol which notices the sender regarding the conditions when the packets are notdelivered to the receiver because of trouble. It also checks whether the receiver exists or not beforetransmission.

Internet Information Server (IIS)A Web server software by Microsoft. It is attached to Windows NT.

Internet Packet Exchange/Sequenced Packet Exchange (IPX/SPX)Network protocol standard for use on the Novell NetWare server family of products.

Internet Packet Exchange (IPX)A protocol of NetWare on the network layer. As NetWare once acquired the share of 70% of the market ofpersonal-computer-oriented NOS, it became an industry wide standard. However, as the commercial use ofthe Internet has been spread, TCP/IP became more popular. NetWare is in danger of losing its position inthe market.

Internet Protocol (IP)TCP/IP protocol for packet forwarding.

internetworkTwo or more networks connected by an internal or external router.

interoperabilityAbility for devices on a heterogeneous network to transmit and share data.

Institute of Electrical and Electronic Engineers (IEEE)Creates networking standards for cabling, electrical topology, physical topology and access schemes.

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jabberContinuously sending random data (garbage). Describes a network adapter that locks up the network withcontinuous transmissions.

jam signalA signal sent to the bus from a personal computer that has transmitted frames and whose frames collidewith other frames in the CSMA/CD method.

journalingThe process of logging system activity to facilitate a fast restart when needed.

- K -

kernelThe core of an operating system that is responsible for managing system resources.


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kilobits per second (kbit/s)Unit of measure for data transfer rates; two to the 10th power (1,024) bits per second.

kilobyte (KB)A unit of measure for memory or disk storage capacity; two to the 10th power (1,024) bytes.

kilobytes per second (kbyte/s)One thousand twenty-four bytes per second. Unit of measure commonly used for transfer rates to and fromperipheral devices.

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Laminate Proof (also known as Chromalin)Off-press proofing method in which the film separations are exposed in contact with CMYK film, which islaminated onto a backing substrate to simulate the process of a printing press.

LAN AnalyzerA tool used for analyzing performance and detecting problems of networks. They are provided both ashardware and software. Network administrators use them as a tool of network troubleshooting.

Lines Per Inch (LPI)Measure of the frequency of the dots on a halftone screen.

Local TalkA protocol which connects Macintosh computers to each other.

Local Area Network (LAN)A system that links computers together to form a network, usually with a wiring-based cabling scheme.LANs connect personal computers and electronic office equipment, enabling users to communicate, shareresources such as data storage and printers, and access remote hosts or other networks.

logical unit (LU)Terminal emulation program or application in an SNA network. LUs can communicate with host systems andapplications (LU Type 0, 1, 2, 3, 4 and 7) or with other LUs of the same type (LU Type 6.0, 6.1 and 6.2 only).

login scriptA set of instructions that directs your workstation to perform specific actions when you log in to the network.The network supervisor can create a system-wide login script (which is the same for all users on thenetwork) that instructs all workstations to perform the same actions upon login. Your individual login scriptexecutes after the system-wide login script. It specifies your individual drive mappings.

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mainframe computerA large-scale computer (such as those made by Burroughs, Control Data, IBM, Univac and others) normallysupplied complete with peripherals and software. Also called a host or CPU. Contrast with minicomputerand desktop computer.

mediaPlural of medium. Physical paths over which communications flow, such as copper wires, coaxial cable oroptical fiber.

megabitOne million bits of data. Mbps (megabits per second—10mbps means that 10 million bits of data persecond are transmitted over a network).

megabits per second (Mbit/s)Unit of measure for data transfer rates; two to the 20th power (1,048,576) bits per second.

megabyte (MB)A unit of measure for memory or disk storage capacity; two to the 20th power (1,048,576) bytes.


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Memory MultiplierTM

Advanced EFI technology that enables Fiery® to print images utilizing half of the memory previouslyrequired; results in reduced cost with no loss of speed, quality or resolution.

messageLogical grouping of information at the application layer.

Message Handling Service (MHS)Novell's store-and-forward technology for sending electronic mail messages.

minicomputerA small-scale or medium-scale computer (such as those made by Data General, DEC, Hewlett-Packard andothers) that usually services dumb terminals. Contrast with mainframe computer and desktop computer.

mixed environmentA computer environment, usually a network, in which the operating systems of different machines arebased on different character encoding.

modemLiterally modulator/demodulator. Converts digital data into analog (waveform) signals for transmission alongmedia that carry analog signals and converts received analog signals back into digital data for use by thecomputer. With the advent of digital lines, there is a also a new kind of modem, called a digital modem, thatdoesn't actually modulate or demodulate signals but is merely responsible for their transmission over digitallines.

modulationThe process of converting digital signals into analog signals by modulating a carrier frequency.

moireUndesirable pattern in color printing resulting from incorrect screen angles of overprinted halftones.

motherboardMain circuit board of a computer that holds the central processing unit, memory slots for expansion, Busesfor connecting peripherals and other devices.

MS-MailAn electronic mail software by Microsoft.

multicastSpecial form of broadcast in which copies of the packet are delivered to multiple stations, but only a subsetof all possible destinations.

multiple name space supportThe method that allows various workstations running different operating systems to use their own familiarnaming conventions. Different operating systems have different conventions for naming files, but withmultiple name space support, the name spaces supported on a volume are configurable so that each file ona given volume has a namethat any workstation can recognize.

Multiple Virtual Storage (MVS)IBM operating system for large host systems.

multiplexerDevice that allows a single communications circuit to take the place of several parallel ones; often used toallow remote terminals to communicate with front-end processor ports over a single circuit.

Multipurpose Internet Mail Extensions (MIME)A protocol that transfers multimedia data such as voices or animation on the Internet.


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Multi Station Access Unit (MSAU)When a token-ring is structured, its logical topology becomes a ring type, but its physical layout is a star typetopology. The MSAU is a line concentrator used for wiring in a token-ring.

multitaskingThe ability to run two or more programs (tasks) on one computer at the same time. The tasks take turnsusing available I/O and CPU cycles.

multivendor networkNetwork comprised of components from different vendors.

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NETADMINNetWare 4 text utility that enables you to create objects and assign rights and properties.

NETBIOS Extended User Interface (NetBEUI)A program to be the interface between the network layer protocol and LAN card driver in the LAN manager.By separating LAN card driver and network layer protocol, a LAN card can handle multiple network layerprotocols.

NetWare Access ServerPC-based application server software from Novell that enables network managers to provide remote andLAN-based users with access to all NetWare LAN resources, including SNA and TCP/IP applications.

NetWare Administrator (NWADMIN)Graphical NetWare 4 utility that enables you to create objects and assign rights and properties.

NetWare Core Protocol (NCP)A standard for the transport layer or upper strata, and a protocol for utilizing core functions of NetWare suchas file servers and print servers.

NetWare Loadable Module (NLM)An NLM is a software module that can be added to the NetWare 3 or NetWare 4 network operating systemto add functionality to a network server. NLMs can be dynamically loaded on or unloaded from the NetWareserver without having to down the server.

NetWare Network Operating System (NNOS)The network operating system developed by Novell, Inc. The NetWare NOS is loaded on the server whenthe server is booted; it controls all system resources and the way information is processed on the entirenetwork or internetwork.

NetWare shellThe NetWare program loaded into the memory of each workstation. It builds itself around DOS andintercepts the workstation's network requests, rerouting them to a NetWare server.

NetWare UNIX Client (NUC)Software that allows a UnixWare system to behave as a recognized client to NetWare software. TheNetWare network operating system provides services to UnixWare users and applications, allowing accessto remote directories, files and printers on NetWare servers as if they were local.

networkA system that sends and receives data and messages, typically over a cable. A network enables a group ofcomputers to communicate with each other, share peripherals (such as hard disks and printers), and accessremote hosts or other networks.

network adapterThe hardware installed in workstations and servers that enables them to communicate on a network.


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network computingA multivendor computing environment that integrates local and wide area network technologies to provideenterprise-wide connectivity.

Network Basic Input/Output System (NetBIOS)A programmable entry into the network that allows systems to communicate over network hardware using ageneric networking API that can run over multiple transports or media.

Network File System (NFS)A protocol of TCP/IP which enables users to access the HDDs connected to other computers on thenetwork.

Network Information Service (NIS)A protocol which enables more than one UNIX machines to administer users or host computers.

Network News Transfer Protocol (NNTP)A protocol for transferring news.

Network Operating System (NOS)A software application that drives all the services of the network (i.e.: NetWare or Windows NT).

nodeDevice that is connected to a network and is capable of communicating with other network devices. InNetWare, a node is considered to be an end system, such as a workstation.

noiseUnwanted changes in waveform that occur between two points in a transmission circuit.

nondedicatedA device that performs multiple simultaneous functions. For example, a nondedicated network server runsthe network functions and performs as a workstation.

NOTESA groupware software by Lotus. It includes the e-mail function, documents manager, and workflowmanager.

Novell NetWarePopular network server software that allows multiple workstation operating systems (Windows, Macintosh,UNIX, etc.) to share file and print services on a Local Area Network (LAN) or Wide Area Network (WAN).

Novell Virtual Terminals (NVT)A two-part program (one for the DOS system and one for the UnixWare Application Server) that allows DOSclients to access applications running on the Application Server.

NT File System Windows NTFS)A file system unique to Windows NT. It improved the weak points of FAT.

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Offset printingA common printing process which utilizes an intermediate black cylinder to transfer or offset’ a piece from aplate to paper.

open architectureAn architecture that is compatible with hardware and software from any of many vendors.

Open Data-link Interface (ODI)A specifications of LAN cards adopted by Novell’s NetWare. It specifies the part of interface between LAN-card drivers and the protocols of the network layer. By separating LAN-card drivers from the protocols of thenetwork layer, users can choose various protocols of the network layer (IP, IPX, Apple Talk) for a LAN card.


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Open Prepress Interface (OPI)Facility for desktop publishing networks to store high-resolution images on a fast file server and allow user toplace a low-resolution version of the image in the page layout program; file server replaces low-resolutionimage sent by the workstation with the high-resolution version at print time.

Open Shortest Path First (OSPF)A protocol for routers. It administer networks and chooses routes by using concepts of logical groupsdomains and variable length subnets.

Open Systems Interconnection (OSI) reference modelA model for network communications consisting of seven layers that describe what happens whencomputers communicate with one another.

Operation, Administration and Management (OA&M) packageA UnixWare menu-based interface to a suite of system administration and maintenance utilities.operating system (OS)Software that manages a computer system. It controls data storage, input and output to and from thekeyboard and other peripheral devices, and the execution of compatible applications.

ORACLEA database software by ORACLE. It has different products for mainframe, workstations, personalcomputers, and those dealing with various hardware and NOS.

Original Equipment Manufacturer (OEM)Often used to refer to MS-DOS standards, such as OEM code pages.

OS/2An operating system that uses a graphical user interface and was designed by IBM.

OSF/MotifThe Open Software Foundation's non-proprietary GUI standard; includes a window manager and a toolkit.

overprintingPrinting page elements on top of one another without creating a trap.

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packetThe unit of information by which the network communicates. Each packet contains the identities of thesending and receiving stations, error-control information, a request for services, information on how tohandle the request and any necessary data that must be transferred.

packet assembler/disassembler (PAD)Device or program used to create packets of data for transmission over a CCITT X.25 packet data networkand to remove data from the received packets. The most common is a CCITT X.29 PAD, used forpacketizing and depacketizing asynchronous ASCII data.packet switchingPackets are relayed across network along the best route available.

Page Description Language (PDL)Language used to describe a page to a printer; Hewlett Packard LaserJets use PCL (Printer ControlLanguage), plotters have HP-GL (Hewlett Packard Graphics Language), other printers use PostScript.

PANTONE Matching System (PMS)Proprietary system that supplies color swatches for designers and matching inks for printers; used to defineand print specific colors; industry standard for non-process color.

Parallel TransmissionA method of transmitting data by a unit of 8 bits.


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passwordsNetwork security feature. Supervisors of NetWare networks have the option of requiring users to use apassword when they log in to the network. If passwords are required, all users must have uniquepasswords. Passwords in the NetWare network operating system(NOS) are encrypted; that is, they arestored on the server in a format only theserver can decode.

peer-to-peer networkA network consisting of nodes (computers) which all have both client and server capabilities and on whichcommunication and data sharing is carried on directly between nodes, rather than being arbitrated by anintermediary node. On a peer-to-peer network all nodes run the same peer-to-peer operating system, whichgives them both client and server capabilities. Personal NetWare is an example of a peer-to-peer networkoperatingsystem.

performance tuningMonitoring and analyzing the net performance of a system and adjusting its configuration to obtain optimumperformance.

Peripheral Component Interconnect (PCI)A new standard bus for Pentium processors advocated by Intel.

phaseThe wave forms of current and voltage of analog signals are displaced, reaching their peaks at differenttimes. This difference is denoted by the phase angle. Some modems use this phase angle to convert digitalsignals to analog signals.

physical addressData-link layer address of a network device.

pingA tool to detect the response from the IP address designated by TCP/IP, or measure times to receiveresponses. As for the NOS coping with TCP/IP, this tool is provided and used for confirming the connectionor troubleshooting.

pixelPicture element or “dot” in an image. Typical monitor pixel resolutions are 640 x 480, 800 x 600, 1024 x768.

plain textComputer-encoded text that contains only code elements and no other formatting or structuralinformation, such as font size, font type, or other layout information. Plain text exchange is commonlyused between computer systems that might have no other way to exchange information.

platformTerm used as a generic reference to all possible choices for some specific part of the computingenvironment. For example: desktop operating system platform (could include DOS, OS/2 and so on) ornetwork operating system platform (NetWare, LAN Manager, and so on).

Point to Point Protocol (PPP)A protocol which connects LANs in remote areas in the network stratum. PPP has made WANcommunications possible between different manufacturers’ products.

portFor hardware, a connecting component that allows a microprocessor to communicate with a compatibleperipheral. For software, a memory address that identifies the physical circuit used to transfer informationbetween a microprocessor and a peripheral.

Portable Document Format (PDF)Native file format for representing documents independent of the original application software, hardware,and operating system used to create those documents.


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PostScriptDeveloped by Adobe Systems in 1985; computer language that describes appearance of text, graphicalshapes, and images on a page.

PostScript Printer Description (PPD)PostScript files that describe all of the unique features of the printer so driver can display appropriate optionsof the printer.

Primary Domain Controller (PDC)A computer to control the domain in the Microsoft network. There must be a PDC in a domain.

print queueA place to temporarily store the data for printing until the turn to use the print server comes. It is placed onthe hard disk of the server. The stored data can be deleted, or the order of printing can be changed.

Private Branch eXchange (PBX)An in-house switching board system switching outside telephone lines or extension telephones.

process colorMethod of printing a wide spectrum of colors by mixing combinations of four basic colors: cyan, magenta,yellow and black.

protocolA standard method of communication such as IPX/SPX, AppleTalk, and TCP/IP used to transfer databetween two devices.

protocol suiteA collection of networking protocols that provides the communications and services needed to enablecomputers to exchange messages and other information, typically by managing physical connections,communications services and application support.proxy serverA proxy server is used for connecting internal networks to the Internet. It has the function to obtaininformation from the Internet on behalf of internal personal computers. It also has the function to protectunauthorized access via the Internet to internal networks.

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queueA line or list formed by items waiting for service, such as tasks waiting to be performed, stations waiting forconnection, or messages waiting for transmission.

queryProcess of extracting data from a database and presenting it for use.

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Random Access Memory (RAM)Short-term memory resource located in a computer. The larger amount of RAM, the larger the size of thefiles that can be processed.

Raster Image Processor (RIP)Part of an output device that rastenzes information so that it may be printed onto film or paper.

rasterizationConversion of PDL data into a bitmap for printing or display.

real-timeAn on-line computer that generates output nearly simultaneously with the corresponding inputs. Often, acomputer system whose outputs follow its inputs by only a very short delay.


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redundancyA duplicate capacity that can be called upon when a failure occurs; having more than one path to a signalpoint.

registrationPrecise placement of the four printing plates on a press so each color prints in their correct relationship to allthe others; poor registration results in blurry double images or gaps between colors.

registryA Windows file that stores user preferences, including international settings.

renderingThe way in which a character is graphically displayed.

Remote Access Server (RAS)A computer that receives access from remote places via public circuits.

resolutionThe output measurement of an image expressed in dots per inch (dpi), pixels per inch (ppi) or lines per inch(lpi).

resource(1) An element, such as a string, icon, bitmap, cursor, dialog, accelerator, or menu, that is included in aMicrosoft Windows resource (.RC) file. (2) Any item that needs to be translated.resource sharingA directory, printer, or application object that is shared on the network.

rich textText saved with formatting instructions that multiple applications, including compatible Microsoftapplications, can read and interpret.

rightsRights control which directories and files a user can access and what the user is allowed to do with thosedirectories and files. Rights are assigned to directories and files by the network supervisor.

RIP-While-PrintFeature that enables the Fiery® to begin processing new pages while current pages are printing, increasingthroughput on multi-page documents.

routerA software and hardware connection between two or more networks, usually of similar design, that permitstraffic to be routed from one network to another on the basis of the intended destinations of that traffic.

Routing Information Protocol (RIP)A protocol on routers used in TCP/IP. At regular intervals, routers automatically exchange informationregarding newly connected nodes or damaged lines. When they receive requests for transmission, routerschoose the shortest routes between senders and receivers.

RS-232CA serial interface protocol regulated by the Electronic Industries Association (EIA) of the US. It is often usedfor connecting modems to computers.

- S -screen anglesRenders an image properly by assuring cyan, magenta, yellow and black halftone screens are at exactangle to one another; incorrect angles can result in an undesirable moire pattern.

scriptA system of characters used to write one or several languages. Characters denote isolated sounds,syllables, or word elements and are governed by a general set of rules for creating text, such as defaultwriting direction.


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Sequenced Packet Exchange (SPX)A NetWare protocol for transport layer. This is the protocol of connection type similar to TCR

Serial Line Internet Protocol (SLIP)A protocol for IP connection by using RS-232C.

serial transferA method of transferring data 1 bit at a time.

serverA computer that provides shared resources to network users.

Server-Based NetworkTypically used in larger (10 or more station) networks.

Sequenced Packet Exchange (SPX)A protocol by which two workstations or applications communicate across the network. SPX uses NetWareIPX to deliver the messages, but SPX guarantees delivery of the messages and maintains the order ofmessages on the packet stream.

serverA computer on the network capable of recognizing and responding to client requests for services. Theseservices can range from basic file and print services to support for complex, distributed applications. Forexample, a distributed database management system can create a single logical database across multipleservers.

Server Advertising Protocol (SAP)SAP is a protocol for sending information regarding the existence of servers and their functions to clientsand other servers.

Service Advertising Protocol (SAP)A NetWare feature that advertises the services available on the Applications Server.

shielded cableCable that has a layer of insulation to reduce electromagnetic interface.

Simple Network Management Protocol (SNMP)A protocol that manages the host computers or gateways used in TCP/IR

Software Development Kit (SDK)A set of tools and libraries for creating software applications for Windows operating systems.

spanningA technique for improving I/O performance by placing frequently-used segments of a file system or databaseon separate disks.

spot colorColor printed with custom ink rather than with a process color combination.

SQL ServerA relational database software for Windows NT by Microsoft.

standaloneA computer that is not connected to a network.

STARRTM CompressionFiery® compression technology that enables true document printing and storage of RIPed files.


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star topologyOne end of each cable in a star topology attaches to a central hub while the other end attaches to a singlecomputer. The computers can be positioned in a radial fashion with the hub located in the center, like thespokes of a wheel.

stripingA technique for improving I/O performance by interleaving file systems or data bases across multiple disks.

Structured Query Language (SQL)A language to operate relational databases. It is developed by IBM, and approved to be the internationalstandard for database language in 1987 ISO meeting. It can be used for general computers to personalcomputers, and can retrieve the databases spread over different types of computers.

supervisorThe person responsible for the administration and maintenance of a network or database. A supervisor hasaccess rights to all volumes, directories and files.

switchAlso known as a switching hub, has the ability to direct packet traffic to its correct network destination byreading the address information included in each packet.

switching HUBConventional hubs function logically in the same way as the bus-type LAN, where personal computers sharea transmission route. However, switching hubs enable each personal computer to exclusively use thetransmission route to make the most use of the 1 0-Mbps transfer speed by using a switching technology.

synchronousDuring a data transmission between computers, a response is returned from the receiver after a certain timein accordance with the data length sent by the sender. For this purpose, both sending and receiving sidesmust make the starting time and ending time match. This is the synchronization, and the method of sendingdata while synchronizing is called the synchronous transmission.

Synchronous Data Link Control (SDLC)IBM-defined link-control protocol that is code-independent.

System Application Architecture (SAA)A set of IBM-defined standards designed to provide a consistent environment for programmers and usersacross a broad range of IBM equipment, including microcomputers, minicomputers and mainframes.

System Fault Tolerance (SFT)Duplicating data on multiple storage devices so that if one storage device fails, the data is available fromanother device. There are several levels of hardware and software system fault tolerance. Each level ofredundancy (duplication) decreases the possibility of data loss.

System Management Server (SMS)A network administration system for WindowsNT developed by Microsoft.

System Network Architecture (SNA)A type of network architecture announced by IBM in 1974. It systematized protocols for hardware andsoftware in order to comprehensively manage networks centering on IBM’s mainframes. Its main purposewas to control communications between mainframes and terminal units. It was the model of OSI and othermanufacturers’ mainframe architecture.

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Tagged Image File Format (TIFF)Standard file format for exchange bitmapped images (usually scans) between applications.

telephonyGeneric term to describe voice telecommunications.


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TelnetProtocol in the TCP/IP suite that governs character-oriented terminal traffic.

terabyteA unit of measure for memory or disk storage capacity; two to the 40th power (approximately one trillion)bytes.

terminalA device, usually equipped with a keyboard and display, capable of sending and receiving data over acommunications link.

terminal emulationSoftware that allows a microcomputer to function as a dumb terminal.

terminatorA small connector which contains a resistor. Terminators attach to each end of a coax cable in a bustopology.

text elementSmallest unit of text that can be displayed or edited.

Thicknet (10Base5)This term describes a larger diameter (approx. 0.5.”) Coax cable. This cable can carry signals farther thanthinnet coax and is typically used as a “backbone.”

Thinnet (10Base2)This term describes small diameter (approx. 0.25") coax cables. Six cable styles fall into this generaldesignation. Ethernet uses types RG-58/U or RG-58/AU. Ethernet connection most commonly used in newnetwork installations because of lesser cost and ease of use versus other Ethernet connections; data travelsat 10Mb/sec.

Token BusA system of communication by circulating tokens. Its wiring topology is the bus type LAN.

Token RingPhysical network connection technology developed by IBM and most commonly used in large corporations.

topologyThe physical layout of network components (cable, stations, gateways, hubs and so on). There are threebasic interconnection topologies, star, ring and bus networks.

transceiverNetwork component that performs both transmitting and receiving functions.

Transmission Control Protocol/Internet Protocol (TCP/IP)A protocol suite and related applications developed for the U.S. Department of Defense in the 1970s and1980s specifically to permit different types of computers to communicate and exchange information with oneanother. TCP/IP is currently mandated as an official U.S. Department of Defense protocol and is also widelyused in the UNIX community.

trapOverlap that prevents white spaces from appearing along the edges of adjacent colors in an image due toslight misalignment or movement of the separations on press.True Color SystemsMonitors that display more than 16 million colors (24 bits per pixel).

twisted-pair wiringTwo wires, usually loosely spun around each other to help cancel out any induced noise in balanced circuits.


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Undercolor Removal (UCR)Process of removing CMY percentages that make up a gray element within darker colors and replacing thanwith an appropriate amount of black.

uninterruptible power supply (UPS)A backup power unit that provides continuous power even when the normal power supply is interrupted.

UNIXOperating system developed by AT&T Bell Laboratories. Allows a computer to handle multiple users andprograms simultaneously.

UnixWare operating system (OS)Novell's UNIX operating system for PCs.

userAny person who attaches to a server or host.

user accountsNetWare security feature. Each user on a NetWare network has a user account. This account determineswhat name the user uses to log in to the network, the groups the user belongs to and what trusteeassignments the user has. User accounts are maintained by the network supervisor.

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V.32A standard for the transmission speed of 9600 bps used for modems.

V.32bisA standard set by ITU-T for the modem with transmission speed of 14,400 bps.

V.34A standard set by ITU-T for the modem of two-wire and full-duplex transmission with a speed of 28,800 bps.

V.42An ITU-T standard for error correcting procedure. A program in a modem handles error correction.

V.42bisA protocol for data compression method recommended by CCITT. It has interchangibility with MNP class 5.

value-added process (VAP)An application that runs on top of NetWare 2 network operating systems. VAPs tie in with the networkoperating system so that print servers, archive servers and database servers can provide services withoutinterfering with the network's normal operation.VAXA Digital Equipment Corporation minicomputer.

vector graphics (images)Graphics displayed using a technology that specifies how an image is represented by using vector notation;for example, a starting point, a length and the direction that the line to be drawn from the starting point is totake. From a mathematical perspective, a vector graphics image is simply a collection of individual points,lines and curves.

vertical applicationAn application that is specific to one area of use. For example: an accounting application or a legalapplication.

Virtual CircuitOne physical line can be used as more than one logical line, making each personal computer is using adedicated line. TCP is a protocol for communication by establishing virtual circuits.


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Virtual Memory System (VMS)Operating system for DEC VAXs.

Visual C++Microsoft's object-oriented C compiler.

volumeA volume is the highest level in the NetWare directory structure, residing at the same level as a DOS rootdirectory. A volume represents a physical amount of hard disk storage space.

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What You See Is What You Get (WYSIWYG)Describes the idea that a printed image is visually identical to the same image when viewed on a computermonitor.

Wide Area Network (WAN)Multiple LAN or physical connections that span over a long distance (i.e.: across many buildings; betweencities or countries).

win32 APIThe set of 32-bit functions supported by Windows.

win32s APIA subset of the Win32 API that makes it possible to create a single binary file that runs on Windows 3.1and on all 32-bit versions of the Windows platform.

windows 95The 32-bit successor to Windows 3.1, Microsoft's entry-level operating system.

Windows Internet Name Service (WINS)The computers connected to the Microsoft network must be given names. When those computerscommunicate extending over the router, the access between networks can be possible by exchanging thecomputer names by servers.

Windows NT ServerThe high-end version of Windows NT that includes additional features for servers.

workgroupWorkgroup – A collection of computers (not users) that form an administrative unit and do not belong to adomain. In a workgroup, each computer tracks its own user- and group-account information, and does notshare this information with other workgroup computers.

workgroup managerWorkgroup manager is a user classification in the NetWare 3 and NetWare 4 network operating systems.Workgroup managers have supervisory control over any user or user group they create on the network.

workstationAny individual personal computer that is connected to a network.

World Wide Web (WWW)A system to distribute contents by using Internet. The receiving side receives the contents by the softwarecalled “browser.” As users can distribute data regardless of hardware or operating software, it has greatlycontributed to the widespread use of Internet.

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X.25A CCITT standard that defines the communications protocol for access to packet-switched networks. Astandard protocol for packet switching, and a representative standard in the X series recommendations.Packet switching circuit is the dedicated circuit for data transmission between computers. The fee is


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determined by the number of packets sent, not by the time of circuit used. A packet is a certain volume ofdata, and one packet is the data of 256 bytes or 1042 bytes lengths. X.25 is the standard equal to that ofphysical layer, data link layer, and network layer in OSI.

X.400Open Systems Interconnection (OSI) standard that defines how messages are to be encoded for thetransmission of electronic mail and graphics between dissimilar computers and terminals; defines what is inan electronic address and what the electronic envelope should look like. The X.400 standards are a subsetof, and conform to, the X.25 standard approved by the Consultative Committee for International Telegraphyand Telephony (CCITT).

X Window SystemStandard set of display-handling routines developed at MIT for UNIX workstations; they allow the creation ofhardware-independent graphical user interfaces.

zoneOn a local area network such as AppleTalk, a subgroup of users within a larger group of interconnectednetworks.

networkfundament&#.pdf

Documents

network printing

network functionality

network architecture

network administration

common network problems

network print services

appropriate media

appropriate topology