LAN

1
LAN

• Eric Wong
• CS 147
• Fall 2008

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What is LAN?

• LAN stands for Local Area Network
• A LAN is a network that connects multiple
  computers
• These computers may be in the same room, same
  building, or spread out throughout multiple
  buildings

3
LAN
4
Characteristics of LAN

• A network of two or more computers
• All computers in the network connected by cables
  or wi-fi
• Does not require leased communication lines

5
Components of a network

• Ethernet
• Hubs
• Individual Computers
• Protocol
• NICs
• Network Software
• Server

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Ethernet

• Uses Ethernet cables to physically connect
  computers to a network

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Ethernet (cont)

• May be wireless using radio waves for two-way
  communication
• Ethernet protocol formally known as IEEE 802.3
• IEEE is the Institute of Electrical and
  Electronic Engineers

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Ethernet (cont)

• Called IEEE 802.3 because it was defined in
  February 1980

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Hubs

• A Junction Box with multiple ports for Ethernet
  cables to connect to
• Sends all data it receives to every computer in
  the network
• MAC (Medium Access Control) addresses

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Hubs (cont)

• Computers ignore all information that is
  addresses to a different MAC
• Hubs use half-duplex mode
• Each computer can only send or receive data at
  the same time
• Cant do both at once

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Network Switch

• Alternative to a Hub
• Full Duplex Functionality
• Nodes can receive and send data at the same time
• Sends data to specific MAC addresses only instead
  of every computer

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Network Switch (cont)

• Superior to Network Hubs

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Computers

• Allows users to interface with the network
• Computers on a network share resources and/or
  information

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Protocol

• Ethernet is a communications protocol
• They define the rules that allow computers to
  communicate with each other
• Protocol operations send signals to the desired
  network and attempts to find a connection

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TCP/IP

• Another common communication protocol in LANs
• TCP stands for Transmission Control Protocol
• IP stands for Internet Protocol
• Also used for Internet connections

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NIC

• NIC stands for Network Interface Card
• Installed into an empty slot on the motherboard
• May be built into the motherboard
• Ethernet cables connect from the Hub or Switch to
  the NIC

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NIC (cont)

• Every computer in a network has one
• All NICs connected to the network must use the
  same architecture

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Network Software

• Software that uses all the hardware to create a
  networking environment
• Allows administration of network
• Many operating systems contain networking
  software
• Also available from vendors

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Server

• Server performs a special service on the network
• May be spread out over multiple computers
• Typically one computer dedicated to server
  functions

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Server (cont)

• Server computer is built differently
• Stores a majority of the data in a network

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The Purpose of LAN

• It allows shared file access between computers
  quickly
• Share peripherals
• Transfer data between computers at a high rate

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Disadvantages

• Computers must be physically close to each other
• Security issues

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Security

• With Hubs, packet sniffers allow access to data
  intended for other computers
• Viruses on one computer may threaten whole network

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WAN

• Stands for Wide-Area Network
• Computer network on a much larger scale than LANs
• Internet is an example of WAN.

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Larger Networks

• LANs may connect to other LANs or WANs to form an
  even larger network
• Usually done with a router
• Router receives data and forwards it to the
  correct location

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Sources

• Anissimov, Michael. "What is a Local Area
  Network." WiseGEEK. 18 Nov. 2008
  lthttp//www.wisegeek.com/what-is-a-local-area-netw
  ork.htmgt.
• Kayne, R. "What are Networking Hubs." WiseGEEK.
  19 Nov. 2008 lthttp//www.wisegeek.com/what-are-net
  working-hubs.htmgt.
• Kayne, R. "What is Ethernet?" WiseGEEK. 19 Nov.
  2008 lthttp//www.wisegeek.com/what-is-ethernet.htm
  gt.
• White, David. "What is TCP/IP." WiseGEEK. 18 Nov.
  2008 lthttp//www.wisegeek.com/what-is-tcpip.htmgt.

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Sources (cont)

• "What is Computer Networking." Senior Corps Tech
  Center. Corporation for National and Community
  Service. 20 Nov. 2008 lthttp//www.seniortechcenter
  .org/hardware_and_software/what_is_network.phpgt.