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LAN Review

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What is a Network? A group of computers and devices connected together for the purpose of sharing resources and services

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What is a LAN?LAN A group of computers in a single location where all cabling belongs to the company

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What is a WAN?WAN Two or more LANs connected together using a telecommunication service (WAN Link) such as T1, Frame Relay, DSL, PSTN etc.

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What is a WLANWLAN This is a LAN that uses Radio Frequency technology to allow for communication among computers and devices

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Role of Computers in a Network Client- computer or device that specializes in knowing how to ask for services in a network. Example: Workstation in a network Server- Computer or device that specializes in knowing how to provide services in network. Example: Print Server in a network Peer- Computer or device that may be able to be both a server or a client at the same time. Example: Workstation in a simple network (peer-to-peer network)

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What is the Network Medium? Cabled/Wired o UTP (cat 5, 5E, 6, 7) o Coaxial o Fiber Optic (single mode, Multi mode) Wireless o Radio o Microwave o Infrared

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What are ProtocolsProtocols Set of rules that allows computer to communicate with each other

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Network Protocols TCP/IP Nwlink or IPX/SPX NetBEUI

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Network Software NOS o Windows Server 2008 o Windows Server 2003 o Windows 2000 Server o Windows NT o Novell Netware 6.5 o Unix o Linux

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Network Services The reason for setting up a network in the first place: File and Print DHCP (Dynamic Host Configuration Protocol) DNS (Domain Naming Service) Security E-mail Application or Database Web / Proxy Mail/FTP/IM/Chat RAS (Remote Access Service)

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Network Types Peer to peer Client/server

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Advantages of Peer-to-Peer Easy to install and configure o Most Client OS already have the components required to set the computer as part of a peer to peer network Individual machines do not depend on the presence of a dedicated server Individual users control their own shared resources Inexpensive to purchase and operate Need no additional equipment or software beyond a suitable operating system. Best for networks with less than 10 users

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Disadvantages of Peer-to-Peer Security applies to a single resource at a time Users may be required to use as many passwords as there are shared resources. Each machine must be backed up individually to protect all shared data. The machine that shares resources suffers reduced performance There is no centralized organizational scheme to locate or control access to data

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Advantages of Client/Server Centralized User Accounts, Security, and access controls simplify network administration More powerful equipment means more efficient access to network resources A single password for network logon delivers access to all resources Server based networking makes the most sense for networks with 10 or more users or any network where resources are used heavily.

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Disadvantages of Client/Server Server failure renders the network unusable, or it results in loss of network resources. Special purpose server software requires allocation of expert staff, which increases expenses. Dedicate hardware and software add to the cost.

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What are Topologies?Topologies The physical shape computers and devices create when connected together The different topologies are: BUS STAR Ring Mesh Hybrids

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Topologies Bus (not commonly found in LANs anymore) o needs termination (signal bounce) o Adding devices disrupts the network o Cable failure hard to find Star (Most common topology) o Requires a hub/switch o Easy to troubleshoot o Requires more wiring

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Topologies Ring o No beginning and no end o Uses token passing o Active topology (regenerates signal from device to device) Mesh o More Fault tolerant

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Variation of Major Topologies (Hybrids) Star-Bus o Backbone interconnect two or more hubs Star-Ring o Physical Star, but logical ring o The way the IBM token ring Works.

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What are Networking Models? A model describes the different stages data needs to go through in order to go from one computer to another. Examples are TCP/IP and the OSI models

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OSI Networking Model 7 Layers o Application email o Presentation message is compressed and encrypted o Session tells the other side the message is coming o Transport breaks up into packets and gives each a sequencing # TCP o Network o Data link mac address o Physical set of rules that tells how things will be transmitted

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IEEE 802.X This standard describes the different technologies (architectures) used to connect computers together. The specifications covered in the Data link layer in the OSI model are too broad and can be subdivided into Logical Link Control Media Access Control (MAC)

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IEEE 802.X Standards of interest to us 802.3 Ethernet Networks 802.11 Wireless Networks 802.15 Wireless PAN (Blue Tooth)

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TCPI/IP Networking model 4 layers o Application Layer o Transport o Internet Layer o Network Interface Layer

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TCP/IP Protocols Application layer o Telnet, FTP, HTTP, SMTP o DHCP, DNS, TFTP, SNMP Transport Layer o TCP, UDP Internet Layer o ICMP, ARP, RARP, IP

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Computer/device ID/Addressing Every computer or device which is part of a TCP/IP network includes a network card. Every network card needs to have: Physical address (MAC address)MAC address Logical address (IP address)IP address

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IPV4 (IP Version 4)Addressing Supports 4.3 billion addresses 32 bit address (Dotted decimal notation). 32 Zeros and Ones 4 octets of 8 bits (8+8+8+8=32) The addresses are divided into Class A, B, C, D, E according to network size. Private vs. Public Addresses. (Private addresses are only valid in a private network not the Internet. Public are valid in the Internet) o Ex. Private address. 10.0.0.0/8, 172.16.0.0 to 172.31.0.0, and 192.168.0.0/24

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IPV6 Addressing 128 bit address Supports 3.410 38 addresses The U.S. Government has specified that all federal agencies must deploy IPv6 by 2008. Normally written as eight groups of four hexadecimal digits. For example, 2001:0db8:85a3:08d3:1319:8a2e:0370:7334.

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Communication types Unicast (One to one) Broadcast (One to all) Multicast (One to a group)

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IP address Class A First Octet starts with binary 0 First octet represents Network ID (0-127) Next three octets represent hosts (16 million) Example: 80.28.29.205

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IP address Class B First octet starts with binary10 (128-191) First and second octet represent network ID Third and fourth octet represent hosts (65,534 hosts) Example: 145.23.89.60

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IP address Class C First octet starts with binary 110 (192-223) First, second and third octet represent network ID. The last Octet represents the host ID. Class C networks have 254 hosts Example: 197.45.67.87

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IP Address Class D First octet starts with binary 1110 (224-239) Used for multicasting

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IP address Class E First octet starts with 11110 (240-255) Reserved for experimental use and cannot be used for address assignment

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Subnet Mask The subnet mask represents the number of bits in the IP address that identify the network address. The sending computer needs to know this in order to decide whether the packet is meant for the local network or for another network. Default Subnet masks are: Class A 255.0.0.0 o 11111111 00000000 00000000 00000000 Class B 255.255.0.0 o 11111111 11111111 00000000 00000000 Class C 255.255.255.0 o 11111111 11111111 11111111 00000000

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Binary to decimal conversion Binary= 01001011 This is equivalent to Decimal=64+8+2+1=75 1286432168421 01001011

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Binary Conversion Binary Decimal _____________________________________ 10000000 128 11000000 192 11100000 224 11110000 240 11111000 248 11111100 252 11111110 254 11111111 255