comptia network+ certification support skills (2009...

CompTIA Network+ Certification Support Skills (2009 Objectives)

Study Notes G520eng ver019

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Acknowledgements

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Study Notes Table of Contents

Page iii

Table of Contents Course Introduction i

Table of Contents ............................................................................................................. iii About This Course........................................................................................................... vii

Module 1 / Network Fundamentals 1

Module 1 / Unit 1 Network Topologies and the OSI Model 2

Network Basics..................................................................................................................2 Network Topologies...........................................................................................................9 The OSI Model ................................................................................................................15 Network Protocols and TCP/IP ........................................................................................25

Module 1 / Unit 2 LAN and WLAN Technologies 33

IEEE 802 Standards........................................................................................................33 Characteristics of Transmission Media ............................................................................36 Ethernet (IEEE 802.3) .....................................................................................................43 Ethernet Media Specifications .........................................................................................45 Wi-Fi (IEEE 802.11).........................................................................................................49

Module 1 / Unit 3 Cabling and Connectors 55

Selecting Network Cable .................................................................................................55 Twisted Pair Cable (UTP / STP / ScTP)...........................................................................56 Coaxial Cable ..................................................................................................................60 Fiber Optic Cable ............................................................................................................61 Serial Cable.....................................................................................................................65

Module 1 / Unit 4 WAN Technologies 71

WAN Basics ....................................................................................................................72 Switched Networks..........................................................................................................73 Telecommunications Networks........................................................................................76 Packet-switched Services................................................................................................83 Local Loop Services ........................................................................................................87 Wireless WANs ...............................................................................................................95

Module 1 / Summary Network Fundamentals 103

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Course Introduction CompTIA Network+ Certification Support Skills (2009 Objectives)

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Module 2 / Addressing and Protocols 105

Module 2 / Unit 1 Addressing 106

TCP/IP Protocol Suite....................................................................................................106 MAC Address ................................................................................................................108 Internet Protocol Basics.................................................................................................112 IP Routing Basics ..........................................................................................................122 Automatic Address Assignment.....................................................................................127 ICMP .............................................................................................................................131 IP Version 6...................................................................................................................133

Module 2 / Unit 2 Routing Protocols 145

IP Routing .....................................................................................................................145 Routing Protocol Characteristics....................................................................................148 Routing Protocols ..........................................................................................................152

Module 2 / Unit 3 Transport Protocols 157

Transmission Control Protocol (TCP) ............................................................................157 User Datagram Protocol (UDP) .....................................................................................160 TCP/IP Ports .................................................................................................................161 Name Resolution...........................................................................................................162

Module 2 / Unit 4 Application Protocols 169

TCP/IP Services ............................................................................................................169 Email (SMTP / POP3 / IMAP) ........................................................................................169 World Wide Web (HTTP)...............................................................................................174 File Transfer Protocol (FTP) ..........................................................................................178 Telnet and Secure Shell (SSH)......................................................................................181 Conferencing and VoIP Protocols (SIP / RTP)...............................................................182 Simple Network Management Protocol (SNMP) ............................................................187 Network Time Protocol (NTP)........................................................................................189

Module 2 / Summary Addressing and Protocols 193

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Study Notes Table of Contents

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Module 3 / Security and Authentication 195

Module 3 / Unit 1 Security Threats and Mitigation Techniques 197

Security Basics..............................................................................................................197 Social Engineering.........................................................................................................198 Malware.........................................................................................................................200 Network Attack Strategies .............................................................................................203 Policies and Procedures................................................................................................214 Device Security .............................................................................................................217 Training .........................................................................................................................222

Module 3 / Unit 2 Network Security Appliances 226

Secure Network Topologies...........................................................................................226 Firewalls and Proxy Servers ..........................................................................................231 Intrusion Detection Systems ..........................................................................................237

Module 3 / Unit 3 Network Access Security and Authentication 243

Encryption and PKI........................................................................................................244 Remote Connectivity Protocols......................................................................................250 Wireless Security...........................................................................................................265 Authentication................................................................................................................267 Network Access Control ................................................................................................279 Remote Administration Tools.........................................................................................282

Module 3 / Summary Security and Authentication 291

Module 4 / Installation and Implementation 293

Module 4 / Unit 1 Installing Network Infrastructure 295

Wiring Standards...........................................................................................................295 Wiring Distribution .........................................................................................................297 Cable Testing Tools.......................................................................................................314

Module 4 / Unit 2 Installing Basic Network Devices 320

Network Adapters..........................................................................................................320 Intranetwork and Internetwork Devices..........................................................................330

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Module 4 / Unit 3 Installing Wireless and Remote Networks 345

Setting Up a Wireless Network ......................................................................................345 Remote Links ................................................................................................................354

Module 4 / Unit 4 Advanced Network Infrastructure 360

Advanced Features of Switches ....................................................................................360 Performance Management Appliances..........................................................................368 Configuring DHCP.........................................................................................................375 Configuring DNS ...........................................................................................................376 Security Appliances .......................................................................................................378

Module 4 / Summary Installation and Implementation 385

Module 5 / Management, Monitoring, Troubleshooting 387

Module 5 / Unit 1 Configuration Management 389

Configuration Management Concepts............................................................................389 Documentation ..............................................................................................................391

Module 5 / Unit 2 Network Monitoring 397

Network Performance Optimization ...............................................................................397 Monitoring Systems and Performance...........................................................................398 Network Monitoring Utilities ...........................................................................................400 Logs ..............................................................................................................................409

Module 5 / Unit 3 Network Troubleshooting 412

Troubleshooting Procedures..........................................................................................412 Command Line Interface Tools......................................................................................418 Troubleshooting Reference Model.................................................................................429 Troubleshooting Common Connectivity Scenarios ........................................................430

Module 5 / Summary Management, Monitoring, Troubleshooting 450

Index 451

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Study Notes About This Course

Page vii

About This Course

Who Should Follow This Course?

This course is intended for new or intending network support technicians wishing to qualify with CompTIA Network+ Certification. It is also suitable for experienced technicians who require an industry-backed credential that validates their skills and knowledge.

CompTIA Network+ validates the knowledge and skills of networking professionals. It is an international, vendor-neutral certification that recognises a technician’s ability to describe the features and functions of networking components and to install, configure and troubleshoot basic networking hardware, protocols, and services.

CompTIA website

What are the Course Prerequisites?

You should have the following skills and experience prior to attending the course:

♦ Taken and passed both CompTIA A+ Certification exams or have equivalent knowledge and experience.

♦ Six months to one year of post A+ Certification support experience.

♦ Experience of supporting end-users and PC-based systems.

Optionally, you can take a prerequisites test to check that you have the knowledge required to study this course at www.gtssupport.com/flower27/N10-004/index.htm.

Course Outcomes

This practical "hands-on" course will teach you the fundamental principles of installing and supporting networks. On course completion, you will be able to:

♦ Describe the features of different network protocols and products for LANs, WANs, and wireless networks.

♦ Understand the functions and features of TCP/IP addressing and protocols.

♦ Identify threats to network resources and appropriate security countermeasures.

♦ Install and configure network cabling and appliances.

♦ Manage, monitor, and troubleshoot networks.

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Study of the course can also help to prepare you for vendor-specific technical support qualifications and act as groundwork for more advanced training. Other qualifications available include:

♦ Cisco Certified Network Associate (CCNA) - a foundation-level certification of competency in Cisco networking appliance installation and configuration.

♦ Microsoft Certified Systems Administrator / Engineer / IT Professional (MCSA / MSCE / MCITP) - Windows-specific qualifications; passing CompTIA’s Network+ Certification plus either Server+ or Security+ Certification can satisfy the requirements for the elective part of the certification, as well as providing a solid groundwork for the further study required for MCSA / MCSE (Windows Server 2003 track) or MCITP (Windows Server 2008 Server Administrator / Enterprise Administrator track).

♦ Corporations such as Novell, HP, Lotus, and 3Com also recognise CompTIA Network+ as part of their certification tracks

♦ Help Desk Support Analyst - The Help Desk Analyst certification series, administered by the Help Desk Institute (www.thinkhdi.com), certifies learners’ customer service and Help Desk management skills. Various levels of certification are available, including Customer Support Specialist, Help Desk Analyst and Help Desk Manager.

About the Course Material

The course material has been prepared as an aid for your use throughout the training course. You may keep this manual for your own reference after the course is finished. We hope you will find the course material useful for future reference.

Course Organisation

This course book contains the study notes for you to refer to in class and to review at home as you prepare for the exam. The course is divided into several modules, each covering a different subject area. Each module is split into a series of units containing related topics for study. Each unit has a set of review questions designed to test your knowledge of the topics covered in the unit. Answers to the review questions are located in the companion volume.

Throughout the course, there will be ample opportunity for you to learn through practical work. A series of "hands-on" labs help to familiarise you with the concepts and technologies that are taught on this course.

At the back of the book there is an index to help you look up key terms and concepts from the course.

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The accompanying book contains a list of the CompTIA Network+ certification objectives (and where in the study notes you can find useful material to prepare for each objective), tips for taking the CompTIA exams, the practical labs for you to complete in class, a glossary of terms and concepts used in computer support, and answers to the end of unit review questions.

When you have completed the course and want to prepare for the exam, you can take a practice test at www.gtssupport.com/flower27/N10-004/index.htm.

Save 10% on your exam fees - visit www.gtslearning.com/voucher to register for your discounted coupon.

Conventions Used in the Course

Certain conventions have been followed to help you use this course material. These are especially useful for following the practical lab exercises.

Bullet Points

Steps for you to follow in the course of completing a task or hands-on exercise and review questions are indicated by numbered bullet points. Other bullet points indicate learning objectives and feature lists.

File Conventions

The steps to follow to open a file or activate a command are shown in bold with arrows. For example, if you need to access the Control Panel in Windows, this would be shown in the text by: Start > Settings > Control Panel.

Commands

Commands or information that needs to be supplied by you that are entered from the keyboard are shown in Courier New bold. For example: Type [email protected]

Displayed Text and Buttons

Information that is displayed on the screen by the computer is shown in sans serif bold. This includes button text and messages. For example: Click OK, Click Continue...

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Key to Symbols Used in the Notes

Icon Meaning

A note or warning about a feature

More information on this topic can be found in the unit mentioned

An area for your notes

Review questions to help test what you have learned

A hands-on exercise for you to practise skills learned during the lesson

CompTIA Authorised Quality Curriculum Program

The logo of the CompTIA Authorised Quality Curriculum Program and the status of this or other training material as "Authorised" under the CompTIA Authorised Quality Curriculum Program signifies that, in CompTIA’s opinion, such training material covers the content of CompTIA’s related certification exam.

The contents of this training material were created for the CompTIA Network+ Certification Essentials exam (exam code: N10-004) covering CompTIA certification exam objectives that were current as of 8 January 2009.

CompTIA has not reviewed or approved the accuracy of the contents of this training material and specifically disclaims any warranties of merchantability or fitness for a particular purpose. CompTIA makes no guarantee concerning the success of persons using any such "Authorised" or other training material in order to prepare for any CompTIA certification exam.

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How to Become CompTIA Certified

This training material can help you prepare for and pass a related CompTIA certification exam or exams. In order to achieve CompTIA certification, you must register for and pass a CompTIA certification exam or exams.

In order to become CompTIA certified, you must:

1) Select a certification exam provider. For more information please visit http://certification.comptia.org/resources/registration.aspx

2) Register for and schedule a time to take the CompTIA certification exam(s) at a convenient location.

3) Read and sign the Candidate Agreement, which will be presented at the time of the exam(s). The text of the Candidate Agreement can be found at http://certification.comptia.org/resources/candidate_agreement.aspx

4) Take and pass the CompTIA certification exam(s).

For more information about CompTIA’s certifications, such as their industry acceptance, benefits, or program news, please visit http://certification.comptia.org

CompTIA is a not-for-profit information technology (IT) trade association. CompTIA’s certifications are designed by subject matter experts from across the IT industry. Each CompTIA certification is vendor-neutral, covers multiple technologies, and requires demonstration of skills and knowledge widely sought after by the IT industry.

To contact CompTIA with any questions or comments, please call (1) (630) 678 8300 or email [email protected].

It is CompTIA’s policy to update the exam regularly with new test items to deter fraud and for compliance with ISO standards. The exam objectives may therefore describe the current "Edition" of the exam with a date different to that above. Please note that this training material remains valid for the stated exam code, regardless of the exam edition. For more information, please check the FAQs on CompTIA’s website http://certification.comptia.org/customer_service).

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Study Notes Network Fundamentals

Page 1

Module 1 / Network Fundamentals

The following CompTIA Network+ domain objectives and examples are covered in this module:

CompTIA Network+ Certification Domain Areas Weighting 1.0 Network Technologies 20% 2.0 Network Media and Topologies 20% 3.0 Network Devices 17% 4.0 Network Management 20% 5.0 Network Tools 12% 6.0 Network Security 11%

Refer To Domain Objectives/Examples Unit 1.1 2.3 Identify common physical network topologies

Star • Mesh • Bus • Ring • Point to point • Point to multipoint • Hybrid

2.7 Explain common logical network topologies and their characteristics Peer to peer • Client/server

4.1 Explain the function of each layer of the OSI model Layer 1 - physical • Layer 2 - data link • Layer 3 - network • Layer 4 - transport • Layer 5 - session • Layer 6 - presentation • Layer 7 - application

Unit 1.2 1.7 Compare the characteristics of wireless communication standards 802.11 a/b/g/n (Speeds • Distance • Channels • Frequency)

2.6 Categorise LAN technology types and properties Types (Ethernet • 10BaseT • 100BaseTX • 100BaseFX • 1000BaseT • 1000BaseX • 10GBaseSR • 10GBaseLR • 10GBaseER • 10GBaseSW • 10GBaseLW • 10GBaseEW • 10GBaseT) • Properties (CSMA/CD • Broadcast • Collision • Bonding • Speed • Distance)

Unit 1.3 2.1 Categorise standard cable types and their properties Type (CAT3, CAT5, CAT5e, CAT6 • STP, UTP • Multimode fibre, single-mode fibre • COAX • Serial • Plenum vs. Non-plenum) • Properties (Transmission speeds • Distance • Duplex • Noise immunity [security, EMI] • Frequency)

2.2 Identify common connector types RJ-11 • RJ-45 • BNC • SC • ST • LC • RS-232

Unit 1.4 2.5 Categorise WAN technology types and properties Type (Frame relay • E1/T1 • ADSL • SDSL • VDSL • Cable modem • Satellite • E3/T3 • OC-x • Wireless • ATM • SONET • MPLS • ISDN BRI • ISDN PRI • POTS • PSTN) • Properties (Circuit switch • Packet switch • Speed • Transmission media • Distance)

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please telephone +44 (0)207 887 7999 or email [email protected]

Module 1 / Unit 1 CompTIA Network+ Certification Support Skills (2009 Objectives)

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Module 1 / Unit 1 Network Topologies and the OSI Model

Objectives

On completion of this unit, you will be able to:

♦ Use basic terminology to describe different types of network.

♦ Understand what is meant by a topology and identify the key physical and logical network topologies:

⎯ Star

⎯ Mesh

⎯ Bus

⎯ Ring

⎯ Point-to-point / point-to-multipoint

⎯ Hybrid

⎯ Peer-to-peer / client-server

♦ Describe the functions of the layers of the OSI Model.

♦ Understand the basic features of the TCP/IP network protocol suite.

Network Basics

A network is two or more computer systems linked together by some form of transmission medium that enables them to share information. It does not matter whether the network contains two or thousands of machines; the concept is essentially the same.

A network will provide services to its users. Historically, these services have included access to shared files and folders and printers and database applications. Modern networks are evolving to provide more diverse services, including web applications, Voice over IP, and multimedia conferencing.

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Study Notes Network Topologies and the OSI Model

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Types of Network

To attempt to clarify the size and nature of individual networks, the industry has developed terms that broadly define the scope of different types of network.

Network Definitions LAN A LAN (Local Area Network) is defined as a

network that does not exceed a distance of 1.25 miles (2 km) from end to end.

CAN A CAN (Campus Area Network) is a multi-building network though limited in scope to a single geographical location and covering the same sort of distance as a LAN.

MAN A MAN (Metropolitan Area Network) is defined as a network that covers the area of a city that is no more than tens of miles (tens of kilometres). It can operate at speeds that are comparable with LANs.

WAN A WAN (Wide Area Network) is a network in which the distance exceeds 1.25 miles (2 km). A WAN often comprises a series of LANs that have been joined together.

Internet The Internet is a worldwide network of networks based on the TCP/IP protocol. The Internet is not owned by a single company or organisation. The term "internet" is also used to describe any series of interconnected networks.

Intranet An intranet uses the same technologies as the Internet, but it is owned and managed by a company or organisation. An Intranet is typically implemented as a LAN or WAN.

Extranet An extranet is an intranet that is also accessible to selected third-parties, such as customers or suppliers.

Topologies

The shape or structure of a network is described as the network topology. There are two types of network topology:

♦ Physical topology describes the actual appearance or layout of the network.

♦ Logical topology describes the flow of data through the network.

Within a given topology, the following terms are used to describe components of the network:

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Node / Host

A node is any device (such as a workstation, server, or printer) that can communicate on the network. Each node must have a unique address. The term host is often used in TCP/IP networking to mean the same thing while a node on a wireless network is also called a station.

Transmission Media

Information must be transferred between nodes using some form of media. Typically, this takes the form of a cable but wireless media using technologies such as radio waves or microwaves can provide the same function.

Intranetwork Devices

Most networks use extra devices to facilitate connections between nodes. Rather than using cables to link the nodes directly, each node is connected to an intranetwork device such as a hub or switch.

Segment

Segments are parts of a larger network that are linked together by an intranetwork device. All nodes on the same segment use the same type of transmission media and have the same bandwidth.

Bandwidth is a measure of how much data can be transferred through a link. See Unit 1.2 for more information.

The term segment is also used loosely to mean a subnet within a network (see below) or a network within an internetwork.

Backbone

A network is typically divided into segments either to cope with the physical restrictions of the network media used or to improve performance (or both). From the point-of-view of performance, communications between segments need to be carefully controlled.

A backbone describes a fast link between two other segments of a network. The backbone carries all the communications occurring between nodes in separate segments.

The standard rule for network design used to be that 80% of traffic should occur within the same segment with only the other 20% passing between segments.

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Internetwork Devices

Separate networks can be joined using internetwork devices such as routers. Such networks may use different types of transmission media and protocols (see below).

The term Intermediate System (IS) can be used to distinguish nodes with routing (or switching) capability from End Systems (ES).

Subnet

A subnetwork (or subnet) is a logical grouping of hosts within a single network. Subnets must use internetwork devices to communicate.

Topology Example

Network boundaries

The graphic above illustrates typical network boundaries. The whole network is connected to the wider Internet via a router. The router is also used to divide the network into two subnets.

Within each subnet, a switch is used to allow nodes to communicate with one another and (through the router) the other subnet and the Internet. The link between each node and the switch is a segment. High bandwidth backbone segments are used between the router and the Internet and the router and the two switches.

Protocols

A protocol is a set of rules enabling systems to communicate (exchange data). A protocol generally defines the format in which data can be exchanged.

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Two of the most important functions of a protocol are to provide addressing (describing where data should go) and encapsulation (describing how data should be packaged for transmission). The basic process of encapsulation is for the protocol to add data fields in a header to whatever data (payload) it receives from an application or other protocol.

A single network will involve the use of many different protocols.

Clients and Servers

Network clients are computers (or software) on the network that allow users to request shared resources on the servers. Client computers are often referred to as workstations.

A server provides shared resources on the network and allows clients to access this information. There are a number of different types of server:

♦ Network Servers provide network services, such as name resolution, authentication, or proxy services.

♦ File and Print Servers share resources amongst clients.

♦ Application Servers provide centralised processing. Some examples include:

⎯ Virtual applications (desktop software hosted on a server rather than installed to a client machine [Windows Terminal Services for example}).

⎯ Web applications (accessed via a web browser).

⎯ Database platforms such as SQL Server and Oracle accessed directly or through a web application.

♦ Messaging Servers provide email, chat, and/or conferencing functionality. Widely used LAN-based messaging systems include Microsoft Exchange, Lotus Notes, and Novell GroupWise.

♦ Media Servers host streaming Audio/Video (A/V) applications.

In many situations, one machine might provide some, or even all, of these functions. In larger networks, machines may be dedicated to a subset of these functions. However, they are all servers.

Clients and servers can be organised into two different logical topologies: server-based or peer-to-peer.

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Server-Based Networks

A server-based network uses a dedicated central server (or servers) to provide access to resources. Security is managed centrally by a system administrator who determines access to these resources.

Every client can talk to the file server, but they cannot talk to one another.

Server-based Network

The first server-based Network Operating System (NOS) for PCs was developed by Novell and appeared as NetWare in 1985. While NetWare is still available, the most widely used server NOS are Microsoft Windows Server, UNIX / Linux, and Apple Mac OS X Server.

The main strengths of a server-based system include the following:

♦ Performance - the clear distinction between server and client means that the server software can be optimised to support many clients simultaneously and provide fast response and high data throughput.

♦ Security - all major server-based systems provide sophisticated security.

♦ Administration - services are centralised making them easier to manage than decentralised "peer-to-peer" systems.

♦ Scalability - server-based systems are designed to support a wide range of organisation sizes. Often additional servers are added to increase capacity.

The disadvantages include the following:

♦ Cost - server-based systems are usually more expensive both in terms of the hardware and the network operating system required. In addition, client licenses must be purchased for each machine using resources.

♦ Complexity - experienced system administrators are required to cope with the complexities of managing these systems.

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Peer-to-Peer Networks

For larger organisations, the investment in a server-based system is appropriate but for small organisations it can be very expensive. Peer-to-peer networks were developed as a low cost alternative in the early 1990s. Desktop or workstation versions of Microsoft Windows support up to 10 computers in a peer-to-peer configuration and Linux and Apple Mac OS X are also suitable for this use.

A peer-to-peer system does not have a dedicated server. Each computer on the system is a "peer" of the others and each may act as both a client and a server. This means that every user may share folders on his or her hard disk and also share peripherals such as printers and fax modems.

Peer-to-Peer Network Every client may talk to every other client.

The main advantages are as follows:

♦ Equipment and software costs are much lower. In the case of Windows, most machines are sold with the software pre-loaded. For small networks (of up to about 10 users) they provide a cost-effective entry to networking.

♦ Installation and management is simple compared with server-based systems.

The disadvantages include the following:

♦ Peer-to-peer systems typically use machines of a lower specification than dedicated servers. The overhead of acting as a workstation as well as a server affects performance.

♦ Peer-to-peer networks are difficult to manage because they are based on the concept that each user is responsible for his or her own machine. For example, it is possible that one user might switch off his or her machine while another is using resources on that machine.

♦ Lack of security. The security relies on each user controlling access to the resources on his or her own PC. As well as (relatively) uncontrolled access to resources, this can mean that data does not get backed up properly. If security is an issue, peer-to-peer systems should not be used.

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Network Topologies

As mentioned earlier, the network topology describes the physical or logical structure or shape of the network.

A topology is described in terms of nodes and links. In the simplest type of topology, a single link is established between two nodes. This is called a point-to-point (or one-to-one) connection. Because only two devices share the connection, they are guaranteed a level of bandwidth.

Point-to-point Connection

The graphic above illustrates a dedicated point-to-point link using a single cable but point-to-point links are more likely to be implemented using switching devices.

A multipoint (or multi-drop or point-to-multipoint) connection is any connection between three or more devices. These multiple devices must share the available bandwidth.

Multipoint Connections

Bus Topology

The simplest example of a bus topology is two computers directly connected by a single cable.

A physical bus topology with more than two nodes is a true multipoint connection. All nodes attach directly to a single main cable. The signal normally travels down the cable in both directions from the source and is received by all nodes connected to the cable. The bus is terminated at both ends of the cable to absorb the signal when it has passed all connected devices.

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Physical Bus Topology

This type of physical bus topology is no longer in widespread use. Bus networks are comparatively difficult to reconfigure, impose limitations on the maximum number of nodes on a segment of cable, and are difficult to troubleshoot (a cable fault could be anywhere on the segment of cable). Perhaps most importantly, a fault anywhere in the cable means that all nodes will be unable to communicate.

Star Topology

In a star network, each node is connected to a central point, typically an intranetwork or internetwork device. The central point mediates communications between the attached nodes.

A star topology can implement point-to-multipoint or point-to-point links:

♦ When a device such as a hub or concentrator or wireless access point is used, links are point-to-multipoint. The hub receives signals from a node and repeats the signal to all other connected nodes. Therefore the bandwidth is still shared between all nodes.

♦ When a device such as a switch is used, point-to-point links are established between each node as required. The circuit established between the two nodes can use the full bandwidth capacity of the network media.

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Node (Workstation)

Node (Server)

Node (Workstation)

Node (Workstation)

Intranetworking Device (Hub)

Node (Workstation)

Star Topology

Advantages

The star topology is the most widely used physical topology.

♦ It is easy to reconfigure.

♦ It is easy to troubleshoot because all data goes through a central point, which can be used to monitor and manage the network.

♦ Faults are automatically isolated to the media, node (network card), or intra-/internetwork device.

Disadvantages

♦ An intra-/internetwork device failure results in failure of an entire section of the network. It represents a Single Point of Failure (SPoF) so redundant links may be required.

♦ It requires more cable relative to other topologies.

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Ring Topology

In the ring topology, computers are connected in a circle. The ring comprises a series of point-to-point links between each device. Signals pass from device to device in a single direction with the signal regenerated at each device.

Node (Workstation)

Node (Workstation)

Node (Workstation)Node

(Workstation)

Node (Server)

Ring Topology

The ring topology is no longer used on LANs but it does remain a feature of many Wide Area Networks (WAN).

Advantages

♦ It uses a relatively small amount of cable, although more than bus topologies.

♦ It is reasonably simple to install.

♦ Two ring systems (dual counter-rotating rings) can be used to provide fault tolerance. These dual rings allow the system to avoid a break in the ring.

Disadvantages

♦ It may be difficult to reconfigure, as adding or removing devices can disrupt the network.

♦ A media or device failure can affect all devices.

♦ It can be difficult to troubleshoot.

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Mesh

Mesh network topologies are commonly used in WANs. This type of network is often found in public networks like the Internet. A wireless LAN operating in "ad hoc" mode (peer-to-peer) is another example of a mesh topology.

In theory, a mesh network requires that every device has a point-to- point connection to every other device on the network (fully connected). This approach is normally impractical and therefore, a "hybrid" approach is used with only the most important devices interconnected in the mesh (partial mesh).

Mesh networks provide excellent redundancy, because other routes, via intermediary devices, are available between locations if a link failure occurs.

Map of the Internet, demonstrating a mesh topology

(created by Matt Britt [en.wikipedia.org/wiki/User:Matt_Britt] and reproduced under the Creative Commons Attribution 2.5 licence)

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Hybrid Topologies

Two different topologies are often combined within the same network to benefit from the advantages of both topologies. The figures below show examples of these combinations.

Star-bus

A star-bus topology is a means of connecting star networks using a bus "backbone" or "trunk".

Star Bus

Star-wired Ring

To make installation and troubleshooting simpler, networks using a logical ring topology are often cabled using a star topology. In this case nodes are attached to the ring indirectly via an intermediary device, such as a Multistation Access Unit (MAU or MSAU).

Star-wired Ring

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Hierarchical

As star networks grow, a common approach is to use the hierarchical topology. This is typical of multi-level buildings and multi-building campus networks.

Hierarchical topology

The OSI Model

The International Organisation for Standardisation (ISO) developed the Open Systems Interconnection (OSI) reference model in 1977. It was designed to aid understanding of how a network system functions in terms of both the hardware and software components. The standard was published in 1983 as ISO 7498.

The OSI Model

Although a theoretical rather than a practical tool, the OSI model has proved invaluable in designing, constructing, and understanding networks. It has increased network interoperability by providing a general model for protocol and specification design.

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As the complexity of computer hardware and software increases, the problem of successfully communicating between these systems becomes more difficult. Dividing these difficult problems into "sub- tasks" allows them to be readily understood and solved more easily. Using this layered approach means that a vendor can work on the design and debugging for a particular layer without affecting any of the others.

Each layer performs a different group of tasks required for network communication. Although not all network systems implement layers using this structure, they all implement each task in some way. The OSI model serves as a functional guideline for network communication and it does not specify any standard.

Network Communication and the OSI Model

For two computers to communicate they must be running the same protocol. Each layer communicates with its equivalent (or peer) layer on the other computer via the lower layers of the model. Each layer provides services for the layer above and uses the services of the layer below.

For example, in the figure below, the transport layer of one computer communicates with the transport layer of another computer by using the services of the network layer and the subsequent lower layers. Both transport layers provide services to their respective session layers when required.

Peer Communication

To try and remember the seven layers, use the following mnemonic: All People Seem To Need Data Processing.

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When a message is sent from one computer to another, it travels down the stack of layers on the sending computer, reaches the receiving computer using the transmission media and then passes up the stack on that computer.

At each level (except the physical layer) a header is added to the data payload, forming a Protocol Data Unit (PDU). These headers are read by the corresponding layer on the other computer and provide control information. This process is known as encapsulation.

A BData Data

DataP DataP

DataPS DataPS

DataPST DataPST

DataPSTN DataPSTN

DataPSTNDL DataPSTNDL

DataPSTNDL DataPSTNDL

Application

Presentation

Session

Transport

Network

Data Link

Physical

Headers

011010100101 OSI Header Information

The OSI Model and Network Protocols

The OSI model is only intended to be a conceptual framework for discussing and designing protocols. As a result, the computer industry often struggles to categorise various protocols and networking technologies into the model.

OSI Reference Model and TCP/IP

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This example demonstrates how the OSI model (a theoretical model) compares with the TCP/IP protocol stack (a real system). The TCP/IP and OSI models were developed concurrently and, therefore, show limited agreement.

It should be noted that some of the OSI layers are performed by a single protocol, some layers are performed by several protocols, and some protocols cover many layers. This reflects the emphasis on performance and efficiency in "real world" networking. Each layer of encapsulation consumes processing power and bandwidth, so actual protocol stacks tend to be simpler than the model.

Physical Layer

The physical layer (PHY) of the OSI model is responsible for the transmission and receipt of bits from one computer to another computer. It specifies the following:

♦ The network medium.

♦ Physical network topology.

♦ Mechanical specifications for using the medium - how ones and zeros are sent as signals over the network medium.

♦ The medium connector and pin-out details - the number and functions of the various pins in a network connector.

♦ The process of transmitting and receiving signals from the network medium including bit transmission, encoding, and timing rules (bit synchronisation).

Connectivity devices found at the physical layer include:

♦ Transceiver / Medium Access Unit (MAU) - the part of a network adapter that sends and receives signals over the network media.

♦ Media Converter - converts one media signalling type to another.

♦ Hub - central point of connection for network segments.

♦ Repeater - amplifies the signal to extend the maximum allowable distance for a media type.

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Data Link Layer

The data link layer is responsible for transferring data between devices. For incoming data, it organises the 1s and 0s (bits) from the physical layer into structured units called frames. In addition, this layer encapsulates packets from the network layer within a frame format for transmission over the network.

The figure below shows a simplified example of a frame1. The data link layer adds control information in the form of fields, such as a source and destination hardware address and error checking values. Other information (not shown in the figure) includes the frame length and network layer protocol identifier.

Preamble Destination Address

Source Address Data Error

CheckingConstruction of a frame

Other functions of the data link layer include:

♦ Addressing a frame to specific computers on the network (using their hardware addresses).

♦ Recognising when the destination address in a frame matches the hardware address of the installed network card and ignoring frames that do not match.

♦ Error control allows the detection and correction of errors. Typical errors include frames lost on route and those recognisable as damaged frames from using Cyclical Redundancy Checks (CRC).

♦ Controlling the data flow prevents fast transmitters from overwhelming slow receivers with data.

The IEEE2 splits the function of the data link layer into two sub-layers. These two sub-layers are known as Media Access Control (MAC) and Logical Link Control (LLC).

1 Some network products use multiple different frame types. For example, on Ethernet there are four frame types. The basic structure remains the same but each frame type contains a slightly different header structure. Devices must communicate using the same frame type. 2 IEEE is the Institute of Electrical and Electronics Engineers is a professional body that oversees the development and registration of electronic standards.

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IEEE 802 sublayers

Media Access Control Sub-layer

The Media Access Control (MAC) sub-layer defines the way in which multiple network adapters share a single transmission medium. It covers the following:

♦ Logical topology - bus or ring.

♦ Media access method - contention or token passing.

♦ Addressing - the hardware address of the network adapter (also known as the MAC address).

Logical Link Sub-layer

The Logical Link Control sub-layer is responsible for establishing and maintaining a link between communicating devices for the transmission of frames. This includes the following:

♦ Service level - connection-oriented or connectionless.

♦ Flow control and error control.

Layer 2 Devices

Connectivity devices found at the data link layer include:

♦ Network adapter (Network Interface Card [NIC]).

♦ Wireless Access Point (AP).

♦ Bridge - provides communications between segments (to extend the range of the network).

♦ Switch - an "intelligent" hub that creates virtual circuits between hosts that want to communicate, negating the effect of contention.

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Network Layer

The network layer is responsible for moving data around a network of networks, known as an internetwork or internet. While the data link layer moves data using a hardware address within a single network, the network layer moves information between networks using logical network and host IDs. The networks are often heterogeneous (that is, use a variety of technologies).

The network layer transfers information between networks by examining the destination network layer address or logical network address, and routing the packet through the internetwork using intermediate systems (routers).

Selection of the path or route to the destination network address is determined dynamically or statically. The packet moves, hop by hop, through the internetwork to the target network. Once it has reached the destination network, the hardware address can be used to move the packet to the target node.

This process requires each logically separate network to have a unique network address.

Other functions of the network layer include:

♦ Fragmenting packets (breaking them into smaller chunks), if required, by a router or different network type. The receiving network layer is responsible for rebuilding the packets.

The general convention is to describe Protocol Data Units (PDU) packaged at the network layer as packets or datagrams and distinguish messages packaged at the data link layer by calling them frames and those at the transport layer by calling them segments. "Packet" is also used to describe PDUs at any layer though.

♦ Flow control - regulating the speed of data transfer.

♦ Error control - detection of transmission errors and retransmission of correct data.

Connectivity devices found within the network layer include:

♦ Routers

♦ Layer 3 switches

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Transport Layer

The transport layer (also known as the end-to-end layer) is responsible for ensuring reliable data delivery so that packets arrive error-free and without loss. The transport layer can overcome any lack of reliability in the lower level protocols. This reliability is achieved using acknowledgement messages that inform the sender the data was successfully received.

The kinds of problems that may occur during the delivery of the data are non-delivery and delivery in a damaged state. In the first case, the lack of acknowledgement results in the retransmission of the data and, in the second case, a Negative Acknowledgement (NACK) forces retransmission.

The transport layer also accomplishes reliable delivery through other mechanisms:

♦ Orderly connection establishment and teardown - under normal circumstances a single connection is created between computers. However, multiple connections can be established to improve throughput.

♦ Segmentation - breaking PDUs from the session layer into a segment format where sequence numbers are used by the receiver to rebuild the message correctly.

♦ Flow control enables one side to tell the other when the sending rate must be slowed.

These features are typical of connection-oriented protocols. Connectionless protocols operate without such mechanisms and are therefore faster, but less reliable.

Upper Layers

The upper layers of the OSI model are less clearly associated with distinct "real world" protocols. These layers collect various functions that provide useful interfaces between software applications and the network transport.

Session Layer

The session layer allows applications running on different computers to communicate using a connection that is called a dialog. The session layer administers the process by establishing the dialog, managing data transfer, and then tearing down the session.

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Managing data transfer is referred to as dialog control. There are three modes:

♦ One-way - only one system is allowed to send messages; the other receives only.

♦ Two-Way Alternate (TWA) - the hosts establish some system for taking turns to send messages, such as exchanging a token.

♦ Two-Way Simultaneous (TWS) - either host can send messages at any time.

The session layer can also provide a synchronisation service for long transactions in which checkpoints are inserted into the data stream (dialog separation). If a problem occurs, only the data transferred after the last checkpoint is resent.

Presentation Layer

The presentation layer transforms data between the format required for the network and the format required for the application. For example, the presentation layer is used for character set conversion. The communicating computers may use different character coding systems (such as American Standard Code for Information Interchange [ASCII] and Unicode); the peer presentation layers agree to translate the data into one of the formats or they will both translate the data into a third format.

The presentation layer can also be conceived as supporting data compression and encryption (scrambling a message so that it can only be read in conjunction with a valid "key"). However, in practical terms these functions are often implemented by protocols running at lower layers of the stack (IPsec for instance).

Application Layer

The application layer provides support services to applications requiring network resources. One of the most utilised services provided by the application layer is file transfer. Different file systems may use entirely different file naming conventions and data syntax and the application layer must overcome these differences.

Other services provided include network printing, electronic mail, directory lookup, and database services.

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OSI Model Summary

Component or Description Layer

Physical 1

Physical topology 1

Bit transmission and encoding 1

Mechanical and electrical specifications for using the media 1

Connector and pin-out details 1

Network interface hardware 1

Transmitting and receiving signals from the network medium 1

Repeaters, hubs, transceivers, media converters, modems 1

802.3 / 802.11 (PHY), RS-232, PDH (T1/E1), POTS, SDH/SONET, DSL, HFC 1

Data Link 2

Logical topology 2

Encapsulation of incoming and outgoing data as frames 2

Network interface hardware addressing 2

Network adapters and Wireless Access Points (MAC), Bridges, Switches 2

802.3 / 802.11 (MAC), VLAN, Frame Relay, ATM, MPLS 2

ARP, PPP, PPTP, L2TP 2

Network 3

Fragmenting packets 3

Network addressing 3

Route discovery and selection 3

Routers, Layer 3 switches 3

IP, ICMP, IGMP, IPsec, NAT 3

Transport 4

Acknowledgement messages and sequence numbers 4

Breaks messages from the session layer into packet format 4

Ensuring reliable data delivery 4

TCP, UDP 4

Session 5

Synchronisation / dialog control (NFS/RPC, SIP, RTP) 5

Connection security (TLS/SSL) 5

Presentation 6

Character set encoding/compression/encryption 6

Application 7

FTP / TFTP, DHCP, DNS, HTTP, SSH, POP3, NTP, IMAP4, Telnet, SMTP, SNMP

7

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Network Protocols and TCP/IP

Protocols are procedures or rules used by networked computers to communicate. For communication to take place, the two computers must have a protocol in common. All protocols require that certain actions are performed in a distinct order when computers communicate.

It is common for several protocols used for networking to be designed to work together. This collection of protocols is known as a protocol suite3. A number of protocol suites have been used for LAN communications over the years, including:

♦ IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) - used by Novell NetWare networks.

♦ NetBEUI (NetBIOS [Network Basic Input Output System] Extended User Interface) - used by early Windows workgroup networks.

♦ AppleTalk - used by early Apple Mac OS networks.

However, the overwhelming majority of networks have now converged on the use of the TCP/IP (Transmission Control Protocol/Internet Protocol) suite.

The TCP/IP suite compared with the OSI reference model

3 Another commonly used term is protocol stack. This term describes a collection of protocols and the logical order in which they work together.

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A Short History of TCP/IP and the Internet

TCP/IP has become an industry standard protocol and, although originally designed for WANs, it is now widely used on LANs as well.

The original research was performed in the late 1960s and early 1970s by the Advanced Research Projects Agency (ARPA), which is the research arm of the US Department of Defense (DOD). The DOD wanted to build a network to connect a number of military sites. The key requirements for the network were:

♦ It must continue to function during nuclear war (development took place during the Cold War). The 7/8th rule required that the network should continue to function even when 7/8th of it was not operational.

♦ It must be completely decentralised with no key central installation that could be destroyed and bring down the whole network.

♦ It must be fully redundant and able to continue communication between A and B even though intermediate sites and links might stop functioning during the conversation.

♦ The architecture must be flexible, as the envisaged range of applications for the network was wide (anything from file transfer to time-sensitive data such as voice).

ARPA hired a firm called BBN to design the network. The prototype was a research network called ARPANET, first operational in 1972. This connected four university sites using a system described as a packet switching network.

Prior to this development, any two computers wanting to communicate had to open a direct channel (known as a circuit) and information was then sent. If this circuit were broken, the computers would stop communicating immediately, which the DOD specifically wanted to avoid.

Packet switching introduced the ability for one computer to forward information to another, thereby superseding circuit-switched networks. To ensure information reached the correct destination, each packet was addressed with a source and destination and the packet was then transferred using any available pathway to the destination computer.

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Data was divided into small chunks or packets (originally 1008 bits). Sending large chunks of information has always presented problems, often because the full message fails to reach its destination at the first attempt, and the whole message then has to be resent. The facilities within the new protocol to divide large messages into numerous small packets meant that a single packet could be resent if it was lost or damaged during transmission, rather than the whole message.

The new network was decentralised. No one computer controlled its operation. The packet switching protocol controlled most of the network operations.

A packet switching protocol is described as "robust" because it can automatically recover from any communication link failures. It re-routes data packets if transmission lines are damaged or if a computer fails to respond, utilising any available network path. The figure below shows an example of an Internet system. A packet being sent from Network A to Network D may be sent via Network C (the quickest route). If this route becomes unavailable, the packet is routed using an alternate route (for example, A-F-E-D).

F

E

A

C

D

B

Packet Switching Networks

Once ARPANET was proven, the DOD built MILNET (Military Installation in US) and MINET (Military Installation in Europe). To encourage the wider adoption of TCP/IP, BBN and the University of California at Berkeley were funded by the US Government to implement the protocol in the Berkeley version of UNIX. UNIX was given freely to US universities and colleges allowing them to network their computers.

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Researchers at Berkeley developed a program interface to the network protocol called Sockets and they and other academic researchers developed higher level protocols for file transfer (FTP), mail transfer (SMTP), and document browsing (HTTP).

During the early 1980s, the National Science Foundation (NSF) used Berkeley TCP/IP to create the Computer Science Network (CSNET) to link US universities. They saw the benefit of sharing information between universities and ARPANET provided the infrastructure. Meanwhile, in 1974 a successor to ARPANET was developed named NSFNET. This was based on a backbone of six supercomputers into which many regional networks were allowed to connect.

The first stage in the commercial development of the Internet occurred in 1990 when a group of telecommunications and computer companies formed a non-profit making organisation called Advanced Networks and Services (ANS). This organisation took over NSFNET and allowed commercial organisations to connect to the system. The commercial Internet grew from these networks.

The Internet now consists of thousands of networks worldwide, connecting research facilities, universities, libraries, and private companies.

Advantages of TCP/IP

There are numerous reasons for the popularity of TCP/IP. Some of these include:

♦ TCP/IP is an industry standard protocol.

♦ It is a routable protocol suite.

♦ It is provided on almost all network operating systems, and therefore allows connectivity between dissimilar systems (for instance, from a UNIX computer to a Windows computer).

♦ It provides connectivity with the Internet.

♦ The protocols are in the public domain and are freely available, which makes it a popular choice for software companies; there are no restrictions on its use and no royalties to pay.

♦ It is a well designed protocol.

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♦ It is an open standard where no single vendor has any control over the protocol and anyone is allowed to use it and develop applications based on it without paying licence or royalty fees.

TCP/IP and Internet Standards

The major network software vendors now include TCP/IP within their products, but it remains an open standard for which anyone can suggest modifications and enhancements. Documents called Request For Comments (RFC) are used to detail current and proposed specifications. No one "owns" TCP/IP and anyone can contribute to its future development.

TCP/IP and the Internet are inextricably linked. Although no organisation owns the Internet or its technologies, a number of organisations are responsible for the development of the Internet and consequently TCP/IP.

Internet Society (ISOC)

The purpose of ISOC (www.isoc.org) is to encourage the development and availability of the Internet. It provides organisational resources to the Internet Architecture Board (IAB).

Internet Architecture Board (IAB)

The IAB (www.iab.org) is the technical committee of ISOC and is responsible for setting Internet standards and publishing these standards as RFCs (Request for Comment).

The IAB governs three groups:

♦ Internet Research Task Force (IRTF [www.irtf.org]) - responsible for TCP/IP related research projects.

♦ Internet Engineering Task Force (IETF [www.ietf.org]) - focuses on solutions to Internet problems and the adoption of new standards.

♦ Internet Assigned Numbers Authority (IANA [www.iana.org]) - manages allocation of IP addresses and maintenance of the top-level domain space. IANA is currently run by Internet Corporation for Assigned Names and Numbers (ICANN).

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IANA allocates addresses to regional registries who then allocate them to local registries or ISPs (Internet Service Provider). The regional registries are APNIC (Asia/Pacific), ARIN (North America and Southern Africa), LACNIC (Latin America), and RIPE NCC (Europe, Northern Africa, Central Asia, and the Middle East)

Request for Comments (RFC)

TCP/IP standards are not developed by a committee but rather by consensus. The process for adopting Internet standards revolves around the production of documents called Request for Comments (RFC).

When an RFC is published, it is assigned the next available number. Anyone can submit a document for publication as an RFC. A technical expert or task force then reviews all documents.

A period of time for comments is followed by an updated draft that responds to these comments. After several drafts, the proposed standard is either accepted or rejected.

The standards for TCP/IP are published via these RFCs. Some RFCs describe network services or protocols and their implementation while others summarise policies.

An older RFC is never updated. If changes are required, a new RFC is published with a new number. It is always important to verify you have the most recent RFC on a particular topic.

Not all RFCs describe standards. Some are designated "informational" while others are "experimental".

The official repository for RFCs is at www.rfc-editor.org and they are also published in HTML format at tools.ietf.org/html.

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Review Questions Unit 1.1: Network Topologies and the OSI Model

Answer the following questions. The correct answers are in the accompanying "Labs and References" manual.

1) What type of device is a switch? An intranetworking device.

2) What term is used to describe a topology in which computers that act as both clients and servers? Peer-to-peer.

3) What type of device is used to implement a star topology? Hub / concentrator / switch / router.

4) Where might a hierarchical star wiring topology be employed? In a CAN (Campus Area Network) / multi-building network.

5) Which of the following is NOT a characteristic of server based networks?

⊕ Every client can talk to one another - FALSE

⊕ Server software can be optimised to provide fast response - TRUE

⊕ Additional servers can be added easily to an existing server-based network - TRUE

⊕ Services are centralised making them easier to manage - TRUE

6) In which sub-layer of the OSI model do network adapter cards operate? MAC.

7) Which layer is being described here: "For incoming data it organises bits from the physical layer into frames. In addition, this layer encapsulates packets from the network layer within a frame format for transmission over the network"? Data Link (Layer 2).

8) True or false? The Session Layer is responsible for passing data to the Network Layer at the lower bound and the Presentation Layer at the upper bound. False.

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9) Atlas Inc. has 100 employees and some Windows-based computers operating as stand-alone servers. The president of the company has hired you to install a network so you need to decide which topology would be appropriate. The president has given you these considerations:

⎯ There is no existing cabling in the company-owned building

⎯ The company expects to grow 45% within the next 12 months

⎯ The network must be reliable and require low maintenance

⎯ Equipment costs should be kept to a minimum

Given the considerations, which topology would you recommend? Star.

10) You need operations to continue if one link fails. How many links does it take to connect three sites? Three.

11) Which two OSI layers define how multiple computers can simultaneously use the network without interfering with each other? Physical and data link.

12) What happens in the network layer if a router cannot transmit a data packet as large as the one received from the source computer? It fragments data into smaller units.

13) Within the OSI Model, which layer handles error checking, addressing and routing information? Network.

14) What body is responsible for agreeing new standards for Internet technologies? IETF.

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Study Notes Installing Network Infrastructure

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Module 4 / Unit 1 Installing Network Infrastructure

Objectives

On completion of this unit, you will be able to:

♦ Understand the application of wiring standards to network design and installation.

♦ Specify and install elements of wiring distribution, such as cabling, cross-connects, and wall outlets.

♦ Identify appropriate tools for network hardware installation and testing.

Wiring Standards

In 1991, the Electronic Industries Association introduced the EIA 568 specification. The standard is called the Commercial Building Telecommunications Wiring Standard and was the first non-proprietary networking scheme for network designers. The document has been subjected to a variety of revisions and updates culminating in the latest version ANSI/TIA/EIA 568-B (www.tiaonline.org)118.

A number of other standards have been developed for different cabling locations (for industrial and residential premises for example) and to apply in different regions. The main standards are as follows:

Type US (ANSI/TIA/EIA)

EU / UK (CENELEC)

ISO (ISO/IEC)

Commercial / Office

568 EN 50173-2 11801

Data Center 942 EN 50173-5 Industrial 1005 EN 50173-3 24702 Residential 570 EN 50173-4 15018

118 The standard comes in three parts: 568-B.1-2001 (General Requirements), 568-B.2-2001 (Copper Cabling Components), and 568-B.3-2002 (Optical Cabling Components); there are also several addenda. At the time of writing, these are all due to be updated to a 568-C series standard.

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Note that use of these standards is not restricted to particular regions. For example, the TIA standards are known globally and not restricted to use in North America. A multinational may choose to implement TIA 568 in all its offices worldwide, while departments of the UK government would be expected to choose CENELEC.

These standards define the grades or "categories" of network cabling and components and also the standard to which they must be installed. They also define topologies for the network and introduce some basic terminology to describe elements of the network.

The purpose of these standards is to enable businesses to plan their infrastructure requirements and ensure Return On Investment (ROI). A standard is generally designed to be valid for about 10 years; that is, a particular class of network installation will support applications using that class for 10-15 years following publication of the standard. An "application" in this sense is a data link protocol, such as Ethernet or SONET. Applications tend to develop faster than infrastructure can be replaced so it is important that the infrastructure installed now be capable of meeting the requirements of applications 10 years in the future.

For this reason, some of the specifications in the standards are quite conservative. For example, UTP-based Ethernet might well work at 100 Mbps at distances longer than 100m, but such an installation would not be standards-compliant.

The various standards are actually broadly similar but there are differences of terminology and specific performance requirements119. The notes here follow the TIA terminology and definitions.

Wiring work is also likely to be subject to legal regulations governing safety in commercial and residential property (building codes). The main requirements are electrical safety (including proper insulation, grounding, and bonding of electrical wire to reduce the risk of electric shock) and fire safety. In the US, these regulations are typically based on the National Electrical Code (NEC) but can vary from state-to-state, county-to-county, or city-to-city. The international standard is IEC 60634, which also forms the basis of the UK’s BS 7671.

Ensure any non-trivial wiring work is supervised by a qualified electrician who knows the local building codes.

Furthermore, communications cabling and broadcasting equipment may be subject to regulation, depending on the frequency in which it operates and power output. In the US, these regulations are formulated by the Federal Communications Commission (FCC).

119 The ISO standard was largely based on TIA 568 and CENELEC generally follows ISO 11801.

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Wiring Distribution

Computer network cabling is often installed in the same manner as a telephone installation.

Basic Wiring Scheme

The main components of a (simplified) structured wiring scheme are as follows:

♦ The computer has a network card installed with a socket for an RJ-45 connector.

♦ A patch cable with the appropriate connector is used to link the network card into a wall outlet with an external RJ-45 port. This must be stranded cable so that it is flexible.

Structured Wiring System

♦ Behind each wall jack is an Insulation Displacement

Connector (IDC). Solid cabling is punched down to the IDC then passes into the wiring ducts (or conduits) and is routed to the main computer room. Solid core cable is used as it is cheaper, has lower attenuation, and repeated flexibility is not required.

♦ In the computer room, the cable is wired into more IDCs in a patch panel.

♦ Finally, another patch cable connects the RJ-45 port on the front of the patch panel to a free port on the switch.

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Structured Cabling System

Most premises have a more complex cabling structure than that described above. In the ANSI/TIA/EIA 568 standard, this is referred to as a structured cabling system. TIA 568 then identifies the following subsystems within the cabling system:

Wiring distribution components

Horizontal Cabling

Horizontal cabling connects user work areas to the nearest horizontal cross-connect120. This is wired in a star topology. Horizontal cabling is so-called because it typically comprises the cabling for a single floor and so is made up of cables run horizontally through wall ducts or ceiling spaces121.

TIA 568 is supplemented by TIA 569 (Commercial Building Pathways and Spaces) and TIA 607 (Grounding / Bonding Requirements). These set out in more detail the requirements and best practice for designing and equipping commercial premises with telecommunications equipment and cabling.

The main fixed cable run can be up to 90m (295 feet); stranded-wire patch cords (between the PC and wall port) and jumpers (a stranded-wire cable without connectors used on cross-connects) can be up to 5m each (16 feet) and no more than 10m (33 feet) in overall length. This is because the attenuation of stranded cable is higher than solid cable.

Cabling should be installed so that it is not a fire, electrical, or trip hazard and is protected from damage, tampering, and EMI. There are several options for securely routing cable:

120 A patch panel is a type of cross-connect that utilises modular jacks and connectors. A cross-connect can also be referred to as a "distribution frame". 121 Note that the term "horizontal cabling" is not prescriptive; horizontal cabling can be installed vertically if necessary, just as backbone cabling can be installed horizontally.

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♦ Conduit - this is a containing pipe made of metal or plastic. Where conduit is surface-mounted it is referred to as a raceway.

When conduit is used for cabling that passes between two floors (riser), make sure the conduit is firestopped. This means that fire cannot spread through the opening created by the conduit. Riser cabling should also conform to the appropriate fire safety standards (similar to plenum spaces).

♦ Trays / J-hooks / caddies - various designs used to suspend cabling. These can be used to keep data and power wiring separate for instance. Cabling should not be laid directly onto ceiling tiles.

♦ Staples - a plastic cup with a nail designed to hold a single cable in place against the wall. Make sure the staple is the correct diameter to hold the cable without crushing it.

♦ Cable ties - plastic or Velcro ties that can be used to bundle cables. When applying a tie, make sure not to cinch it too tightly - there should still be room for the cables to move a little.

♦ Cable management - these are accessories for rack-mounted appliances (such as patch panels and switches) that channel and support cabling, making the installation easier to manage and reducing stress on the connections.

Each bit of cabling and its associated connectors should conform to the appropriate category (Cat5e or Cat6 for instance). Furthermore, the whole link should be installed to the requirements of the same category122. The specific media types recommended by the standard are updated in the various appendices.

See Unit 1.3 for descriptions of commonly used types and categories of network cabling and connectors.

122 One of the main differences between TIA 568 and ISO 11801 is that ISO 11801 refers to the link in terms of its "class" rather than its category.

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Backbone Cabling

Backbone cabling connects horizontal cross-connects to the main cross-connect (optionally via intermediate cross-connects). These can also be described as vertical cross-connects (backbone cabling is more likely to run up and down between floors)123. This is also wired in a star topology.

Maximum link distances between the main cross-connect and horizontal cross-connects (and between main and intermediate and horizontal cross-connects if applicable) are largely dependent on the media type and application.

Coax was once a popular choice for backbone cabling. Twisted-pair backbone cabling is typically either bundles of 6x4-pair or a single 25-pair cable. However, much existing and all new backbone cabling is fibre-optic.

Work Area

The work area is the space where user equipment (PCs or devices such as VoIP handsets) is located and connected to the network. The connection point is the telecommunications outlet (or wall plate). According to the standard, a work area should be served by two links; one for voice and the other for data.

There are many different wall plate designs, suiting different types of mounting and wall materials. Wall plates also support a given number and type of jacks (RJ-11 and RJ-45 or RJ-45 with fibre optic for instance); some plates are modular, allowing the insertion of the required jacks on a case-by-case basis.

4-pair cable should be terminated using the 8-position modular jack (commonly referred to as RJ-45) wired using either the T568A or T568B wiring standard (see below).

Siemon modular wall plate (www.siemon.com)

Optical fibre can be terminated using a suitable duplex connector.

123 Backbone cabling can also be used to connect multiple buildings within a single site, referred to as a campus.

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Telecommunications Room / Equipment Room

The telecommunications room (or space or closet) houses horizontal cross-connects. Essentially, this is a termination point for the horizontal cabling along with a connection to backbone cabling.

The telecommunications room should be a "controlled environment" in terms of heating, air conditioning, and security. The TIA 569 (Commercial Building Pathways and Spaces) standard sets out the requirements for such a space.

The equipment room is similar to a telecommunications room but contains the main or intermediate cross-connects. Equipment rooms are also likely to house "complex" equipment, such as switches, routers, and modems.

Some of the main design considerations for equipment closets are:

♦ Position - in a multi-floor building, telecoms closets should be positioned above one another and ideally in the centre of the building. They should not be positioned near to flood risks (bathrooms and so on).

♦ The space should be of sufficient size to accommodate the equipment (based on the number of work areas supported). The flooring should be able to handle an appropriate loading (50 lbs per ft²).

♦ Equipment should be installed in wall-mounted or free-standing racks. Data communications equipment is designed to fit into standard 19" wide racks124. The height of equipment is measured in "U" units (1.75"). Racks are available in various heights, from 8 to 48U.

♦ There should be a controlled environment (Heating, Ventilation, Air Conditioning [HVAC]).

♦ Lighting should not be in close proximity to equipment.

♦ The area must have an adequate power supply. Equipment such as metal racks must be bonded to the building’s ground system.

♦ Entry to the space must be controlled and restricted to authorised personnel.

124 Racks can be supplied with shelving for equipment that cannot be screwed into it.

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Entrance Facilities / Demarc

Entrance facilities are special types of equipment rooms marking the point at which external cabling (outside plant) is joined to internal (premises) cabling. These are required to join the access provider’s network and for inter-building communications.

The demarcation point is where the access provider’s network terminates and the organisation's ’network begins. A demarc extension is cabling that runs from the demarc point to customer premises equipment such as a router. This would be necessary if (for instance) the routing equipment could not be housed in the entrance facilities.

Installing WAN links is discussed in more detail in Unit 4.3.

Administration

The final element of the cabling system is its administration. Administration schemes are described in the TIA 606 standard. This defines a system of identifiers to use to describe the elements of the network and manage configuration changes125.

Configuration management documentation is covered in detail in Unit 5.1.

Distribution Frames

A distribution frame is another way of describing a cross-connect. It is a passive device allowing the termination and cross-connection of cabling. As described above, these can be installed in a hierarchy:

♦ Main Distribution Frame (MDF) - terminates external cabling and distributes backbone cabling to intermediate or horizontal cross-connects.

♦ Intermediate Distribution Frame (IDF) - optional level of hierarchy for distributing backbone cabling. Note that the TIA 568 standard allows for only one such intermediate level. IDFs would typically be used in a multi-building (campus) network. An MDF in the main building would connect to IDFs in outer buildings, which would connect in turn to horizontal cross-connects on each floor.

125 These are often referred to as MACs (Moves, Adds, Changes).

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Wiring is terminated using a punch-down block. A number of different punch-down block formats have been used for telecommunications and data cabling.

66 Block

A 66 block is an older-style distribution frame used to terminate telephone cabling and legacy data applications (pre-Cat5).

A 66 block comprises 50 rows of 4 IDC (Insulation Displacement Connector) terminals. Inserting a wire and punching it down using the appropriate tool cuts the insulation surrounding the wire and makes a good, secure electrical contact.

The 25-pair cable from the access provider is terminated on one side of the block. On the other side of the block, the terminals terminate the wiring from the PBX, though some 66 blocks may provide a pre-wired RJ-21 (Centronics) connector for a 25-pair cable to make wiring simpler.

A jumper (bridging clip) is installed over the middle two terminals to complete the connection126.

A 66 block could be used to terminate 4-pair data cabling but this is not recommended for Fast Ethernet. In this case, the final two rows of terminals are unused.

110 Block

The 110 block is an updated type of IDC supporting 100 MHz operation (Cat5) and better. "110 block" can describe both a punch-down format and a distribution frame (or wiring block).

In the case of distribution frames, these are available in a variety of configurations, supporting between 25 and 300 pairs. A 110 wiring block is arranged horizontally rather than vertically, offering better density than a 66 block. There is also more space for labelling the connectors and each column of connectors is colour-coded, making management simpler. Each row in the wiring block joins 25 pairs. The incoming wire pairs are fed into channels on the wiring block then a connector block is installed using a punch-down tool to terminate the wiring127. Outgoing wire pairs are then punched into the terminals on the connector blocks (using a different tool) to complete the circuit.

126 This describes a split box; there are non-split blocks that do not require jumpers (all four connectors are electrically joined). A block with 4 terminals per row is an "M" block; there are also blocks with 6 terminals (66B blocks). 127 Connector blocks (110Cs or "C clips") are available for 3-, 4-, and 5-pair applications. Obviously, 4-pair is the choice for Ethernet. Wiring blocks are also available with pre-wired 25-pair cabling and connectors.

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110 wiring blocks provide a flexible means of configuring voice and data networks but you are more likely to encounter 110 IDCs as used in wall plates and patch panels.

RJ-45 Patch Panel

A patch panel has 110-style IDCs on one side and pre-wired RJ-45 jacks on the other side. This greatly simplifies wiring connections and is the most commonly installed type of wiring distribution where connections need to be changed often.

Siemon patch panel (www.siemon.com)

A patch panel may be wired either to T568A or T568B (see below) - make sure you use the same wiring scheme for all the other connectors on your network.

Cabling is the not the only part of the wiring system that must be rated to the appropriate category. For faster network applications (Gigabit Ethernet and better) the performance of connectors becomes increasingly critical. For example, if you are installing Cat6 wiring, you must also install Cat6 patch panels, wall plates, and connectors.

Krone / BIX

66 and 110 blocks are manufactured by a number of companies under licence from AT&T, who developed the systems. There are also several proprietary systems, including Krone / LSA-PLUS (now owned by ADC) and BIX.

Some patch panels may support more than one type of punch-down (110 and Krone for example). Some punch down tools feature removable blades for different products (66, 110, and Krone for instance).

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Wiring Tools and Techniques

The key to installing cabling professionally can be summed up as "Keep it Tidy"! Some of the qualities of tidiness are to:

♦ Adhere to the specified standard.

♦ Leave cables out-of-sight, securely fastened and routed, and labelled.

♦ Test everything.

♦ Document the installation.

Pulling Cable

Installing fixed cable from a bulk spool is referred to as "pulling cable" because the cable has to pulled, carefully, from the telecommunications closet to the work area. While "every job is different", pulling cable involves the following general steps:

1) Identify the path(s) that the cable will take. Some of the main considerations are:

⎯ Do not lay cable in proximity to power cabling, lighting, or transformers128

⎯ Do not lay cable in proximity to heat sources

⎯ Do not exceed the maximum distances allowed

⎯ Introduce as few bends in the cable as possible

⎯ Conceal cable to protect it from tampering or accidental damage

⎯ Provide sufficient links for current usage and growth

⎯ Ensure the wall plates are close enough to the work area (up to 5m) and their position complies with local building codes (in terms of proximity to power jacks and distance from the floor)

⎯ Identify each port with a unique ID

Network management and documentation systems are discussed in Unit 5.1.

128 Cross power cabling at a 90° angle (do not lay data and power cabling in parallel). Power and data cabling must be kept separate both for performance and safety reasons.

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2) Install cable management components (conduit, raceways, or cable trays) along the path and drill any access points through walls and ceilings.

When making changes to the building’s structure, make sure the work conforms to applicable building codes (for example, to firestop any holes punched in walls or ceilings). Be extremely careful not to cut through building services (power, plumbing, and HVAC).

3) Obtain patch panels, wall jacks, and patch cords all wired to the same standard (T568A or T568B; see below).

4) Starting at the patch panel, label the end of the cable with the appropriate jack ID then run it through to the work area129 - there are various tools and techniques for pulling cable through difficult to reach areas, such as ceiling spaces. These include extension poles, pulley systems, tennis balls, and remote control buggies!

When pulling cable, do not subject it to excessive force or bending130. Distorting the cable geometry will reduce its performance. Do not persist with damaged cable - strip it out and install a new length.

5) Leaving enough slack at both ends (a service loop) to make the connection, cut the cable, and label the other end with the appropriate ID.

6) Repeat for all the other cable runs! Use ties and cable management to keep the cable runs neat and tidy (this is called "dressing the cable").

7) When all the cable is in place and properly labelled, you can make the terminations to the patch panel and wall jacks.

129 This is also referred to as a "drop" as in most cases you will be dropping the cable from the ceiling space through a wall cavity. If several cables are going to roughly the same place, you can bundle them and pull them together. 130 The maximum force that can be exerted on 4-pair cable is 25 pounds. Cable should not be bent past the bend radius. The bend radius is the arc of a circle radius that is 4 times the cable's diameter.

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Tools

You could fill a small van and spend a not-so-small fortune on the various tools available for installing and maintaining data cabling. The range of tools you require will of course depend on the cabling work you do, but the following can be considered typical.

♦ Wire stripping / cutting - electrician’s scissors (snips) are designed for cutting copper wire and stripping insulation and cable jackets. Alternatively there are dedicated tools or tools that have replaceable blades for different data cable types. Cable cutting blades should be rounded to preserve the wire geometry. Stripping tools should have the correct diameter to score a cable jacket without damaging the insulation wires. Heavy duty cutters are required for armoured cable.

♦ Punch-down - these tools fix conductors into an Insulation Displacement Connector (IDC). There are different IDC formats (66, 110, and Krone) and these require different blades. Many punch-down tools have replaceable blades though. Blades are double-sided; one side cuts the excess wire at the same time as making the connection.

♦ Crimpers - these tools fix a jack to a cable. The tools are specific to a particular type of connector and cable, though some may have modular dies to support a range of RJ-type jacks.

♦ Fibre optic - tools for cutting, stripping, and connectorising fibre optic cabling cost around 3-4x the price of copper wire tools. Most of the tools are vendor-specific.

♦ Cable pulling - various rods, hooks, pulleys, and spoolers designed to move cable through inaccessible places. You are also likely to need general building tools (such as screwdrivers, drill, hammer, adjustable wrench, saw, utility knife, flashlight, tape measure, masks, and gloves). Most jobs would also require use of a stepladder.

♦ Labelling - correct identification of cables, ports, appliances, and spaces is essential for good network management. There are various label products for patch panels, wall outlets, and cables. Cable ties are useful for bundling related cables and keeping the installation tidy.

♦ Cable testers - to verify wiring installation and termination (see later in this unit for details).

♦ Essentials - never go anywhere without taking a few replacement batteries and a notebook and pen.

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Connecting to IDCs

Both the wall outlet and the patch panel have an IDC or punch down block for each port.

Only use solid cable for cable runs. Stranded cable (used for patch cords) does not work with IDCs.

To connect the wiring to the punch down block, complete the following steps:

1) Remove as little sheath as possible - about an inch and a quarter (2 to 3cm) - and only untwist the pairs for a maximum distance of a half an inch (about 1.3 cm). Excessive untwisting will allow excessive crosstalk between strands and may result in problems.

Cat 6 is more demanding and requires no more than 0.375" (1 cm) of untwisting.

2) Lay the pairs over the appropriate location on the punch down block (normally each block is colour coded).

3) Check again that you have laid the wires in the correct positions!

4) Use a punch tool to simultaneously make the connection and cut the strand to length.

5) Test!

The punch down blocks come in several formats, such as Krone and 110. The appropriate punch tool (or blade) is required for the different formats.

Crimping Cables

Ready-made patch cords are easily available but there may be some circumstances when you need to make one by crimping connectors to the cable.

It is best to use prefabricated patch cords where possible. These are far less likely to create problems.

1) Select the correct type of cable - this must be stranded for a patch cable.

2) Cut a piece of cable of suitable length.

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3) Strip at least ¾ of an inch (2cm) of the cable sheath to expose the inner pairs. To do this using a cable stripper, put the cable in the jaws of the stripper then rotate the tool a couple of times to score or cut the sheath so that it can be pulled off.

4) Untwist the pairs of cables.

It is important not to untwist too much wire or the performance of the cable will be reduced.

5) Using the wiring diagram (see below), place the coloured wires into the correct order.

6) Cut the ends of the inner wires so that they are exactly the same length and just long enough to reach the end of the RJ-45 connector with the bridge positioned over the cable sheath.

7) Make sure the connector is positioned with the spring lever at the bottom.

8) Push the wires all the way into the connector - the copper core should be visible from the end of the connector.

9) Check that the wires are still in the correct order.

10) Push the RJ-45 connector into the crimping tool and squeeze the handles.

11) Check that the cables have been pierced and the bridge is over the cable sheath.

12) Repeat for the other end of the cable.

13) Test the cable using a cable tester - this should identify any crossed wires, incomplete contacts, or crosstalk.

Wiring Standards

Each conductor in 4-pair data cable is colour-coded. Each pair is assigned a colour (Blue, Orange, Green, or Brown). The first conductor in each pair has a predominantly white insulator with strips of the colour; the second conductor has an insulator with the solid colour.

The ANSI/TIA/EIA 568 standard defines two methods for terminating Ethernet connectors: T568A and T568B. The wiring for T568B is shown below:

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Review Questions Unit 4.1: Installing Network Infrastructure

Answer the following questions. The correct answers are in the accompanying "Labs and References" manual.

1) What role do cross-connects play in a structured cabling system? Horizontal cross-connects terminate cabling from each work area and allow their interconnection (via patch panels) or cross-connection (via punch-down blocks) to backbone (vertical) cross-connects.

2) What is cable management? Accessories for rack-mounted appliances that support cable and channel it neatly - avoiding "spaghetti cabling".

3) True or false? "Cat" standards apply only to wiring. False - connectors are also rated to cat standards.

4) What distinguishes a telecommunications room from an equipment room? An equipment room houses more complex equipment (switches and routers) and so has higher requirements in terms of space, power, environmental controls, and security.

5) What would be a typical use of an IDF? To cross-connect backbone cabling in a multi-building (campus) network. The Intermediate Distribution Frame introduces a hierarchy of cable organisation between the Main Distribution Frame and horizontal cross-connects.

6) What is the significance of different IDC formats when planning a wiring job? Each type of IDC requires the use of a specific punch-down tool (or blade).

7) How many connections does the RJ-45 connector house? Eight.

8) 100BASE-T transmit pins are 1 and 2. What colour-code are the wires terminated to these pins under T568A and T568B? Green / White and Green for T658A or Orange / White and Orange for T568B.

9) Which pins are used for the receive pair under 100BASE-T? 3 and 6.

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Study Notes Index

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Index

Where a term or phrase is abbreviated, the abbreviation is the form listed in the index.

1 1000BASE....................... 47 100BASE......................... 46 100-pair ......................... 312 10BASE........................... 45 10GBASE.................. 48, 82 110 Block....................... 303

2 25-pair ........................... 312

4 4B5B................................ 39

5 568A / 568B .................. 309

6 66 Block......................... 303 6to4 ............................... 140

8 802 Standards................. 33 8B10B.............................. 39

A AAA Server.................... 271 Access Point ........... 20, 348 ACL ............................... 231 ACR............................... 432 Active Detection ............ 238 Address Class ............... 114 Addressing ... 109, 113, 118, 121, 127, 133 Administration ....... 302, 391 ADSL............................... 91 Adware .......................... 201 Agent ............................. 188 Analog ............................. 36 Analysis Engine............. 237

Anonymous FTP............ 180 ANSI ................................ 58 ANSI/TIA/EIA 568.... 58, 295 Antenna ........................... 53 Anti-replay ..................... 198 Anti-Virus Software........ 202 Anycast.......................... 136 APIPA.................... 131, 327 AppleTalk ........................ 25 Application Hardening ... 221 Application Layer..... 23, 107 Application Layer Gateway....................................... 234 ARP (Protocol) .............. 109 arp (tool) ........................ 418 arp ping.......................... 426 Asymmetric Encryption.. 247 ATM................................. 84 Attacker ................. 203, 204 Attenuation .............. 42, 432 Authentication.......197, 245, 267, 278 Autonegotiation ............... 46 AWG................................ 56

B Backbone .............. 4, 9, 300 Backdoor ............... 201, 207 Bandwidth........................ 37 Bandwidth Shaper ......... 370 Baseband ........................ 37 Baseline................. 390, 399 Beacon .......................... 351 BGP............................... 155 Binary/Decimal Conversion....................................... 113 Bleed ............................. 436 BNC................................. 60 Bonding ..................... 41, 52 BOOTP.......................... 128 Botnet ............................ 211 Bounce .......................... 436 Bridge ......20, 335, 337, 435 Broadband....................... 37

Broadcast ................42, 124 Broadcast Storm....336, 443 Brute Force Attack.........214 Bus Topology.....................9 Butt Set ..........................317

C CA..................................249 Cable Certifier................316 Cable Modem ................358 Cable Service Providers..93 Cable Tester ..........314, 316 Cable Types ....................55 Cabling ............................55 Cache Pollution .............210 Caching Engine .............378 Callback.........................262 CAM...............................339 CAN ...................................3 Cat 3/5/5e/6 .....................58 CATV ...............................93 CDMA2000 ......................97 cdmaOne .........................95 Cellular Radio ..................95 CENELEC......................295 Central Office...................76 CERT.............................203 Certificate Authority .......247 Channel ...................51, 348 CHAP.............................274 CIDR..............................119 Circuit Switching ........73, 78 Circuit-Level Gateway ...233 Class (IP Addressing)....114 Classful Versus Classless Addressing.....................116 Client .................................6 Coax Cable......................60 Collisions .......................434 Command Line Interface Tools..............................418 Communication..............222 Confidentiality ................198

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Index CompTIA Network+ Certification Support Skills (2009 Objectives)

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Configuration Management...................................... 389 Connectors .... 59, 60, 63, 65 Console Cable................. 67 Content Filter................. 235 Content Switch .............. 364 Contention ....................... 40 Convergence................. 149 CPE ................................. 76 CRC........................... 19, 44 Crimping Cables............ 308 Cross-connect ............... 301 Crossover Cable ........... 311 Crosstalk ................. 56, 432 CSMA.............................. 40 CSU/DSU ................ 79, 355 CX4 ................................. 60

D Dark Fiber........................ 82 Data Link Layer ............... 19 Datagram....................... 112 DCE................................. 66 DDoS............................. 211 Deep Packet Inspection 234 Default Gateway............ 122 Default Ports ................. 161 Demarc.................. 302, 354 Device Security ............. 217 DHCP .... 128, 375, 444, 445 DHCPv6 ........................ 139 Diagram......................... 392 Dial-up ............................. 87 DIAMETER.................... 273 DiffServ.......................... 369 dig.................................. 429 Digital .............................. 36 Digital Certificate ........... 247 Digital Certificates ......... 248 Distance .................... 42, 53 Distance Vector............. 150 Distribution Frame......... 302 DMZ............................... 228 DNS....... 165, 376, 444, 446 DNS Spoofing ............... 210 DOCSIS........................... 93 Documentation .............. 391 DoS ............................... 211 Dotted Decimal Notation113 Downtime ...................... 372

DRDoS .......................... 212 DSL.......................... 90, 357 DSSS............................... 51 DSx.................................. 78 DTE ................................. 66 Dumpster Diving............ 198 Duplex ............................. 41 DVB-S.................... 100, 358

E EAP ............................... 275 EAPoL ...........219, 278, 366 Eavesdropping .............. 205 E-carrier........................... 79 Echo .............................. 433 EDF ............................... 355 EDGE .............................. 96 Education ...................... 222 EGP............................... 155 EIGRP ........................... 153 Email.............................. 169 EMI .......................... 55, 436 Encapsulation.................. 16 Encoding ......................... 38 Encryption ..................... 244 Endpoint Security .......... 279 Enterprise WAN............... 72 Entrance Facilities ......... 302 Environmental Factors .. 436 Equipment Room........... 301 Escalation...................... 415 ESSID............................ 345 ESSID Mismatch ........... 439 Ethereal ......................... 205 Ethernet ..................... 34, 43 EUI-64 ........................... 108 Event Log ...................... 409 Exchange ........................ 76 Exploit.................... 206, 208 Extranet ......................... 227

F Fast Ethernet ................... 46 Fast Link Pulse................ 46 Fault Tolerance ............. 372 FHSS............................... 50 Fiber Optic Cable ............ 61 Filtering.......................... 231 Firewall ..228, 231, 236, 379

Firewire............................67 Firmware........................222 Flow Control ....................21 Footprinting....................205 Fox and Hound ..............315 FQDN ............................162 Fragmentation .................21 Frame ........................19, 43 Frame Relay ....................83 Frequency..........49, 51, 436 FTP........................178, 284 FTTx ................................94 Full Duplex.......................41

G Gain .................................53 GBIC..............................332 Gigabit Ethernet...............47 GPRS ..............................96 GRE...............................255 GSM ................................95

H Half Duplex ......................41 Hashing .........................245 Health Monitor ...............398 HFC ...........................60, 93 HIDS ..............................237 Hierarchical Topology......15 High Assurance SSL .....261 High Availability .............372 High Bandwidth Applications ...................368 Hijacking ........................210 History Log ....................409 Hoaxes ..........................198 Horizontal Cabling .........298 Host ...................................4 Host ID...................113, 114 Host Name.....................162 Host-based Firewall.......236 hostname.......................420 HOSTS ..........................164 Hotfix .............................221 HSDPA ............................97 HTML.............................177 HTTP .............................174 HTTPS...................175, 285 Hub ..................18, 333, 435

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CompTIA Network+ Certification Support Skills (2009 Objectives)

Labs and References

G520eng ver019

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Tel: +44 (0)20 7887 7999 Fax: +44 (0)20 7887 7988 Email: [email protected]

Acknowledgements

www.gtslearning.com

Course Developer .............................................. gtslearning

Editor.......................................................... James Pengelly

This courseware is owned, published, and distributed by gtslearning, the world’s only specialist supplier of CompTIA learning solutions.

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This courseware is copyrighted © 2009 gtslearning. Product images are the copyright of the vendor or manufacturer named in the caption and used by permission. No part of this courseware or any training material supplied by the publisher to accompany the courseware may be copied, photocopied, reproduced, or re-used in any form or by any means without permission in writing from the publisher. Violation of these laws will lead to prosecution.

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Labs and References Table of Contents

Page iii

Table of Contents

CompTIA Network+ Examination Objectives 1

Domain 1.0 Network Topologies........................................................................................2 Domain 2.0 Network Media and Topologies ......................................................................3 Domain 3.0 Network Devices ............................................................................................4 Domain 4.0 Network Management ....................................................................................4 Domain 5.0 Network Tools ................................................................................................5 Domain 6.0 Network Security ............................................................................................6

Exam Tips 7

Registering for the Test .....................................................................................................7 Taking the Test..................................................................................................................7 After the Test.....................................................................................................................8 Retaking the Test ..............................................................................................................8

Labs 9

Answers to Review Questions 93

Module 1 / Network Fundamentals ..................................................................................93 Module 2 / Addressing and Protocols ..............................................................................98 Module3 / Security and Authentication...........................................................................105 Module 4 / Installation and Implementation....................................................................110 Module 5 / Management, Monitoring, Troubleshooting ..................................................115

Glossary 121

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Labs and References CompTIA Network+ Examination Objectives

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CompTIA Network+ Examination Objectives

The material in this course will help you to learn and practise the CompTIA Network+ Certification Examination Objectives (Exam Code: N10-004 / Release Date: 8 January 2009).

It is CompTIA's policy to update the exam regularly with new test items to deter fraud. The exam objectives may therefore describe the current "Edition" of the exam with a date different to that of the objectives. Please note that this training material remains valid for the dated objectives, regardless of the exam edition.

CompTIA Network+ Certification Domain Areas Weighting 1.0 Network Technologies 20% 2.0 Network Media and Topologies 20% 3.0 Network Devices 17% 4.0 Network Management 20% 5.0 Network Tools 12% 6.0 Network Security 11%

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CompTIA Network+ Examination Objectives CompTIA Network+ Certification Support Skills (2009 Objectives)

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The following tables list where the domain objectives of the exam are covered in this course.

Domain 1.0 Network Topologies

Domain Objectives/Examples Unit 1.1 Explain the function of common networking protocols TCP/IP suite • DHCP • ARP • ICMP • IGMP

Unit 2.1

TCP • UDP • DNS Unit 2.3FTP • TFTP • HTTP(S) • SIP (VoIP) • RTP (VoIP) • POP3 • NTP • IMAP4 • TELNET • SMTP • SNMPv2/3

Unit 2.4

SSH • TLS Unit 3.31.2 Identify commonly used TCP and UDP default ports TCP ports (FTP – 20, 21 • SSH – 22 • TELNET – 23 • SMTP – 25 • DNS – 53 • HTTP – 80 • POP3 – 110 • NTP – 123 • IMAP4 – 143 • HTTPS – 443) • UDP ports (TFTP – 69 • DNS – 53 • BOOTP / DHCP – 67 • SNMP – 161)

Unit 2.3

1.3 Identify the following address formats IPv6 • IPv4 • MAC addressing

Unit 2.1

1.4 Given a scenario, evaluate the proper use of the following addressing technologies and addressing schemes Addressing Technologies (Subnetting • Classful vs. classless [e.g. CIDR, Supernetting] • NAT • PAT • SNAT • Public vs. private • DHCP [static, dynamic APIPA]) • Addressing schemes (Unicast • Multicast • Broadcast)

Unit 2.1

1.5 Identify common IPv4 and IPv6 routing protocols Link state (OSPF • IS-IS) • Distance vector (RIP • RIPv2 • BGP) • Hybrid (EIGRP)

Unit 2.2

1.6 Explain the purpose and properties of routing IGP vs. EGP • Static vs. dynamic • Next hop • Understanding routing tables and how they pertain to path selection • Explain convergence (steady state)

Unit 2.2

1.7 Compare the characteristics of wireless communication standards 802.11 a/b/g/n (Speeds • Distance • Channels • Frequency)

Unit 1.2

Authentication and encryption (WPA • WEP • RADIUS • TKIP) Unit 3.3

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Domain 2.0 Network Media and Topologies

Domain Objectives/Examples Unit 2.1 Categorise standard cable types and their properties Type (CAT3, CAT5, CAT5e, CAT6 • STP, UTP • Multimode fibre, single-mode fibre • COAX • Serial • Plenum vs. Non-plenum) • Properties (Transmission speeds • Distance • Duplex • Noise immunity [security, EMI] • Frequency)

Unit 1.3

2.2 Identify common connector types RJ-11 • RJ-45 • BNC • SC • ST • LC • RS-232

Unit 1.3

2.3 Identify common physical network topologies Star • Mesh • Bus • Ring • Point to point • Point to multipoint • Hybrid

Unit 1.1

2.4 Given a scenario, differentiate and implement appropriate wiring standards 586A • 586B • Straight vs. crossover • Rollover • Loopback

Unit 4.1

2.5 Categorise WAN technology types and properties Type (Frame relay • E1/T1 • ADSL • SDSL • VDSL • Cable modem • Satellite • E3/T3 • OC-x • Wireless • ATM • SONET • MPLS • ISDN BRI • ISDN PRI • POTS • PSTN) • Properties (Circuit switch • Packet switch • Speed • Transmission media • Distance)

Unit 1.4

2.6 Categorise LAN technology types and properties Types (Ethernet • 10BaseT • 100BaseTX • 100BaseFX • 1000BaseT • 1000BaseX • 10GBaseSR • 10GBaseLR • 10GBaseER • 10GBaseSW • 10GBaseLW • 10GBaseEW • 10GBaseT) • Properties (CSMA/CD • Broadcast • Collision • Bonding • Speed • Distance)

Unit 1.2

2.7 Explain common logical network topologies and their characteristics Peer to peer • Client/server

Unit 1.1

VPN Unit 3.3VLAN Unit 4.42.8 Install components of wiring distribution Vertical and horizontal cross-connects • Patch panels • 66 block • MDFs • IDFs • 25 pair • 100 pair • 110 block • Verify wiring installation • Verify wiring termination

Unit 4.1

EDFs • Demarc • Demarc extension • Smart jack Unit 4.3

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Domain 3.0 Network Devices

Domain Objectives/Examples Unit 3.1 Install, configure and differentiate between common network devices Hub • Repeater • NIC • Media converters • Basic switch • Bridge • Basic router

Unit 4.2

Modem • Wireless access point Unit 4.3Basic firewall • Basic DHCP server Unit 4.43.2 Identify the functions of specialised network devices Multifunction network devices • CSU/DSU

Unit 4.3

Multilayer switch • Content switch • IDS/IPS • Load balancer • DNS server • Bandwidth shaper • Proxy server

Unit 4.4

3.3 Explain the advanced features of a switch PoE • Spanning tree • VLAN • Trunking • Port mirroring • Port authentication

Unit 4.4

3.4 Implement a basic wireless network Install client • Access point placement • Install access point (Configure appropriate encryption • Configure channels and frequencies • Set ESSID and beacon) • Verify installation

Unit 4.3

Domain 4.0 Network Management

Domain Objectives/Examples Unit 4.1 Explain the function of each layer of the OSI model Layer 1 – physical • Layer 2 – data link • Layer 3 – network • Layer 4 – transport • Layer 5 – session • Layer 6 – presentation • Layer 7 – application

Unit 1.1

4.2 Identify types of configuration management documentation Wiring schematics • Physical and logical network diagrams • Baselines • Policies, procedures and configurations • Regulations

Unit 5.1

4.3 Given a scenario, evaluate the network based on configuration management documentation Compare wiring schematics, physical and logical network diagrams, baselines, policies and procedures and configurations to network devices and infrastructure • Update wiring schematics, physical and logical network diagrams, configurations and job logs as needed

Unit 5.1

4.4 Conduct network monitoring to identify performance and connectivity issues using the following Network monitoring utilities (e.g. packet sniffers, connectivity software, load testing, throughput testers) • System logs, history logs, event logs

Unit 5.1

4.5 Explain different methods and rationales for network performance optimisation Methods (QoS • Traffic shaping • Load balancing • High availability • Caching engines • Fault tolerance) • Reasons (Latency sensitivity • High bandwidth applications [VoIP • Video applications] • Uptime)

Unit 4.4

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Domain Objectives/Examples Unit 4.6 Given a scenario, implement the following network troubleshooting methodology Information gathering – identify symptoms and problems • Identify the affected areas of the network • Determine if anything has changed • Establish the most probable cause • Determine if escalation is necessary • Create an action plan and solution identifying potential effects • Implement and test the solution • Identify the results and effects of the solution • Document the solution and the entire process

Unit 5.2

4.7 Given a scenario, troubleshoot common connectivity issues and select an appropriate solution Physical issues (Crosstalk • Nearing crosstalk • Attenuation • Collisions • Shorts • Open • Impedance mismatch [echo] • Interference) • Logical issues (Port speed • Port duplex mismatch • Incorrect VLAN • Incorrect IP address • Wrong gateway • Wrong DNS • Wrong subnet mask) • Issues that should be identified but escalated (Switching loop • Routing loop • Route problems • Proxy arp • Broadcast storms) • Wireless Issue (Interference [bleed, environmental factors] • Incorrect encryption • Incorrect channel • Incorrect frequency • ESSID mismatch • Standard mismatch (802.11 a/b/g/n) • Distance • Bounce • Incorrect antenna placement)

Unit 5.3

Domain 5.0 Network Tools

Domain Objectives/Examples Unit 5.1 Given a scenario, select the appropriate command line interface tool and interpret the output to verify functionality traceroute • ipconfig • ifconfig • ping • arp ping • arp • nslookup • hostname • dig • mtr • route • nbtstat • netstat

Unit 5.2

5.2 Explain the purpose of network scanners Intrusion detection software • Intrusion prevention software

Unit 3.2

Packet sniffers • Port scanners Unit 5.25.3 Given a scenario, utilise the appropriate hardware tools Cable testers • Protocol analyser • Certifiers • TDR • OTDR • Multimeter • Toner probe • Butt set • Punch down tool • Cable stripper • Snips • Voltage event recorder • Temperature monitor

Unit 4.1

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Domain 6.0 Network Security

Domain Objectives/Examples Unit 6.1 Explain the function of hardware and software security devices Network based firewall • Host based firewall • IDS • IPS

Unit 3.2

VPN concentrator Unit 3.36.2 Explain common features of a firewall Application layer vs. network layer • Stateful vs. stateless • Scanning services • Content filtering • Signature identification • Zones

Unit 3.2

6.3 Explain the methods of network access security Filtering / ACL (MAC filtering • IP filtering)

Unit 3.2

Tunnelling and encryption (SSL VPN • VPN • L2TP • PPTP • IPsec) • Remote access (RAS • RDP • PPPoE • PPP • VNC • ICA)

Unit 3.3

6.4 Explain methods of user authentication PKI • Kerberos • AAA (RADIUS • TACACS+) • Network access control (802.1x) • CHAP • MS-CHAP • EAP

Unit 3.3

6.5 Explain issues that affect device security Physical security • Restricting local and remote access

Unit 3.1

Secure methods vs. unsecure methods (SSH, HTTPS, SNMPv3, SFTP, SCP • TELNET, HTTP, FTP, RSH, RCP, SNMPv1/2)

Unit 3.3

6.6 Identify common security threats and mitigation techniques Security threats (DoS • Viruses • Worms • Attackers • Man in the middle • SMURF • Rogue access points • Social engineering [phishing]) • Mitigation techniques (Policies and procedures • User training • Patches and updates)

Unit 3.1

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Labs and References Exam Tips

Page 7

Exam Tips

Registering for the Test

Save 10% on your exam fees - visit www.gtslearning.com/voucher to register for your discounted coupon.

Two commercial organisations currently administer the CompTIA Certification exams - VUE and Prometric. You can locate a test centre using the links on CompTIA's website:

http://certification.comptia.org/resources/registration.aspx

♦ Arrive at the test centre at least 15 minutes before the test is scheduled.

♦ The test centre administrator will demonstrate how to use the computer-based test system.

♦ You must have two forms of ID - one with picture, both with signature, preferably with your private address (driving licence, passport, and so on).

♦ Books, calculators, laptops, PDAs, or other reference materials are not allowed.

♦ Pens, pencils, and paper are not required! You must not attempt to write down questions or remove anything from the exam room.

♦ It is CompTIA's policy to make reasonable accommodations for individuals with disabilities.

Taking the Test

♦ There are 100 questions which must be answered in 90 minutes. The passing score is 720 on a scale of 100-900.

♦ Read each question and its option answers carefully. Don't rush through the exam as you'll probably have more time at the end than you expect.

♦ At the other end of the scale, don't get "stuck" on a question and start to panic. You can mark questions for review and come back to them.

The Network+ bridge exam code is TBC.

The duration, number of questions, and passing score have not been determined at the time of writing. Contact CompTIA for more information.

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Exam Tips CompTIA Network+ Certification Support Skills (2009 Objectives)

Page 8

♦ As the exam tests your ability to recall facts and to apply them sensibly in a troubleshooting scenario, there will be questions where you cannot recall the correct answer from memory. Adopt the following strategy for dealing with these questions:

⎯ Narrow your choices down by eliminating obviously wrong answers.

⎯ Don't guess too soon! You must select not only a correct answer, but the best answer. It is therefore important that you read all of the options and not stop when you find an option that is correct. It may be impractical compared to another answer.

⎯ Utilise information and insights that you've acquired in working through the entire test to go back and answer earlier items that you weren't sure of.

⎯ Think your answer is wrong - should change it? Studies indicate that when students change their answers they usually change them to the wrong answer. If you were fairly certain you were correct the first time, leave the answer as it is.

♦ Don't leave any questions unanswered! If you really don't know the answer, just guess.

♦ The exam may contain "unscored" questions, which may even be outside the exam objectives. These questions do not count towards your score.

After the Test

♦ A score report will be generated and a copy printed for you by the test administrator.

♦ The score report will show whether you have passed or failed and your score in each section. Make sure you retain the report!

♦ Once you have passed the exam, a certificate and ID card should be with you in 4-6 weeks.

♦ If 8 weeks have passed after taking your exam and you haven't received a copy of your certificate, contact [email protected]

Retaking the Test

If you do fail the certification test at the first attempt, then you can retake it at your convenience. However, should you fail the test at the second, third, or subsequent try, you will not be able to resit the exam for at least 30 days after your last attempt. Study your score report to see which areas of the exam you were weak on.

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Labs and References Labs

Page 9

Labs

Lab 1

Using Virtual PC

The practical labs in this course have been written using Microsoft Virtual PC. The "real" computer (HOST) is installed with Windows. There are two virtual PC images installed on each HOST - LOCAL and ROUTER. The virtual machines are running Windows Server 2003.

You can manage the virtual PCs using the Microsoft Virtual PC shortcut in the Start Menu or Desktop of the HOST. Double-click the server icon in the console to start it.

When the virtual server has booted, to login to a virtual PC session, click the mouse pointer in the VPC window and then use the host key Alt Gr+Delete together. This is the equivalent of Ctrl+Alt+Delete in the HOST.

At the end of various labs you may be required to either save the VPC state or delete the changes made. It is important you select the correct option for the conclusion of a given lab.

How to Close VPC and Commit Changes to Disk

1) Click the Close icon in the top corner of the VPC window and then choose Shut down and save changes.

If the shut down doesn’t proceed as expected, after all disk activity has ceased, then close the VPC by clicking again in the top-right of the window.

In this case, ensure you choose Shut down and save changes.

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Labs and References Labs

Page 55

Lab 15

Configuring DHCP Clients and Servers

Exercise 1: Configuring a DHCP Client

In this exercise you will instruct your computer to obtain its IP addressing information from a DHCP server.

The status bar of the VPC window contains an inverted T. This represents the network settings. The adapter is currently set to "Local only", meaning that each machine can only communicate with other VMs on the same HOST. We will change this to use the host's adapter, enabling communications with VMs on the classroom network.

1) Start both servers then switch to the LOCAL server and log on (Administrator / P@ssw0rd).

2) Alt-click the Network icon, and choose Network Settings.

3) Select Adapter 1 from the drop-down list, and instead of local, select the HOST installed adapter.

4) Click OK.

5) Click the mouse into the VPC window.

6) Select Control Panel > Network Connections then alt-click Local Area Connection and select Properties.

7) Select TCP/IP and click the Properties button.

8) As you can see, the address is currently manually configured - make a note of the configuration now:

____________________________________________________

9) Select the Obtain an IP address automatically radio button.

10) Click OK then OK again.

Exercise 2: Testing the Client

In this exercise you will use ipconfig to find out information about your IP addressing information

1) From the Start menu select Run then type cmd and click OK.

2) Type ipconfig /release.

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Labs CompTIA Network+ Certification Support Skills (2009 Objectives)

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Lab 17

Designing a VLAN

You are a network design engineer. You have recently connected your national HQ campus to a regional head office. The regional head office connects various branch sales offices in the region, and itself links back to the HQ campus. The regional office supports two thousand users, distributed across four floors in a large office building.

The building is flood-wired using Cat 6 cabling and there are various wireless access points in some of the meeting rooms.

Because the leased line that connects to the HQ campus has limited bandwidth, most server-based services are deployed locally.

Discussion: Capacity Planning

In recent discussions with the local IT support staff, you have discovered that users have been complaining about degrading performance in recent weeks. Support staff have recently installed additional services responsible for deploying software updates to the client computers. You suspect that the network is being overloaded and begin investigations.

1) What questions must you ask in order to help determine how network servers are being used?

You should ask what type of services are being used, and determine what volume of network traffic those services might generate. For example, servers that connect to the Internet and download software updates can generate a fair amount of traffic - especially if each server connects to the remote update server individually.

Also, consider the placement of the router that provides the Internet connection. All traffic will flow through it to the subnets that contain the update servers.

You should try to determine the times of day that updates are applied to the computers. Obviously, there will be busy and less-busy times. If possible, these updates should be scheduled for less-busy times to reduce the impact of these servers.

Finally, think about which client computers are receiving the updates. Computers not receiving updates will still be impacted by the traffic generated by those that are.

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Labs and References Glossary

Page 121

Glossary

10xBASE The Ethernet-type networks can be subdivided into several types of network. The IEEE 802.3 standard uses the following notation to indicate Ethernet type: x-BASE-y, where "x" indicates the data rate (in Mbps), "BASE" denotes that baseband transmission is used and "y" either describes the maximum media distance or the cable type. More recent standards define gigabit (1000BASE-Y) and 10 Gigabit (10GBASE-Y) speeds. See also: 802 Protocols, Baseband, Ethernet.

110 Block Punch-down cross-connect format offering high density (supporting up to 300 pairs). 110 wiring blocks are used for various applications. The 110 IDC format is used in most patch panels and wall jacks. See also: IDC.

25-pair / 100-pair Data cabling has four pairs within a single jacket. Telephone cabling often uses bundles of colour-coded 25-pair cables. These are generally unsuitable for data applications because of excessive crosstalk.

568A / 568B Termination standards defined in the ANSI / TIA / EIA 568 Commercial Building Telecommunications Standards. 568A is mandated by the US government and for US residential wiring but the only commercial rule is not to mix the two on the same network. Wiring a cable with both 568A and 568B termination creates a crossover cable.

66 Block Punch-down cross-connect used to terminate telephone wiring. Each 66 block can terminate a single 25-pair cable.

802 Protocols The 802 standards, published by the LAN / MAN Standards Committee of the Institute of Electrical and Electronics Engineers (IEEE), define technologies working at the physical and data link layers of the OSI model. These layers are subdivided into two sub-layers. The Logical Link Control (LLC) sub-layer is used with other 802 protocols, such as 802.3 and 802.11, which are conceived as operating at a Media Access Control (MAC) sub-layer and the physical (PHY) layer. See also: Ethernet (802.3), OSI Model, Wi-Fi (802.11).

802.1X Port authentication framework that requires the device user to authenticate before the device is granted access to the network. 802.1X defines how devices should provide support for Extensible Authentication Protocol (EAP). See also: EAP.

Access Point See: Wireless Access Point.

ACL (Access Control List) A list configured on a resource or appliance (firewall or switch) that determines access / deny access rules. Filtering is often performed on the basis of MAC or IP address.

ADSL See: DSL.

Antenna Component broadcasting wireless signals. Different types of antenna can be used to focus a signal to a particular point or more widely (omni-directional). Many wireless devices use a simple rod-type antenna. See also: Wi-Fi.

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