LAN

Eric Wong

CS 147

Fall 2008

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

LAN

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

Components of a network

Ethernet Hubs Individual Computers Protocol NICs Network Software Server

Ethernet

Uses Ethernet cables to physically connect computers to a network

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

Ethernet (cont)

Called IEEE 802.3 because it was defined in February 1980

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

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 Can’t do both at once

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

Network Switch (cont)

Superior to Network Hubs

Computers

Allows users to interface with the network

Computers on a network share resources and/or information

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

TCP/IP

Another common communication protocol in LANs

TCP stands for Transmission Control Protocol

IP stands for Internet Protocol

Also used for Internet connections

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

NIC (cont)

Every computer in a network has one

All NICs connected to the network must use the same architecture

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

Server

Server performs a special service on the network

May be spread out over multiple computers

Typically one computer dedicated to server functions

Server (cont)

Server computer is built differently

Stores a majority of the data in a network

The Purpose of LAN

It allows shared file access between computers quickly

Share peripherals

Transfer data between computers at a high rate

Disadvantages

Computers must be physically close to each other

Security issues

Security

With Hubs, packet sniffers allow access to data intended for other computers

Viruses on one computer may threaten whole network

WAN

Stands for Wide-Area Network

Computer network on a much larger scale than LANs

Internet is an example of WAN.

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

Sources

Anissimov, Michael. "What is a Local Area Network." WiseGEEK. 18 Nov. 2008 <http://www.wisegeek.com/what-is-a-local-area-network.htm>.

Kayne, R. "What are Networking Hubs." WiseGEEK. 19 Nov. 2008 <http://www.wisegeek.com/what-are-networking-hubs.htm>.

Kayne, R. "What is Ethernet?" WiseGEEK. 19 Nov. 2008 <http://www.wisegeek.com/what-is-ethernet.htm>.

White, David. "What is TCP/IP." WiseGEEK. 18 Nov. 2008 <http://www.wisegeek.com/what-is-tcpip.htm>.

Sources (cont)

"What is Computer Networking." Senior Corps Tech Center. Corporation for National and Community Service. 20 Nov. 2008 <http://www.seniortechcenter.org/hardware_and_software/what_is_network.php>.