Two Network Types Defined by DISTANCE

LAN

WAN

NETWORKS

LAN

LOCAL AREA NETWORK

LAN

Ethernet

A particular type of LAN

Network Components (LAN)

Workstations– microcomputers– minicomputers– workstations– mainframes– terminals– supercomputers

Servers (optional) Media

Interfaces– circuit boards– network adapter– NIC – network

interface card Gateways

– connect dissimilar parts of a network

Bridges– connect similar parts of a

network

Media - cables

Twisted pair– inexpensive– least reliable– easiest to install– what is used in telephone lines– slow

Media - cables

Coaxial– more reliable– what is used in cable TV– harder to install– faster

Media - cables

Fiber optic– works with light waves (lasers)– most reliable– most expensive– fastest– most difficult to work with– becoming the media of choice

TOPOLOGIES

Physical design of a network

Three LAN topologies:

BUSSTARRING

Bus

Single cable

Easy to install

No server

Ring

Single connected cable

Break does not destroy all the connections

Usually does not have a server

Star

Individual cables

Easiest to trouble shoot

Has a server

Network Protocols rules for communicating

Specifies -

type of topology

handshake

synchronous/asynchronous transmission

how data will be packaged

3 Protocol Classifications

Polling

CSMA/CD

Token ring

Polling

Goes to each workstation in turn

Assures that all work stations will access

Problem if there are many workstations

CSMA/CD

Carrier sense multiple access with collision detection

Workstations try to seize the network when they want to access

Problem if two workstations want to access at the same time

Token Ring

Token - electronic device

Token circulates around network

Token is either free or has a message

If it has a message, goes to the receiver and back to sender before continuing

Network SoftwareNetwork Software

Operating system of the Operating system of the networknetwork

Resides on serverResides on server

Controls file transfersControls file transfers

Controls hardware sharingControls hardware sharing

Controls uploading/downloading of filesControls uploading/downloading of files

May include:May include:– electronic mailelectronic mail

– performance analyzation softwareperformance analyzation software

– security softwaresecurity software

– diagnostic routinesdiagnostic routines

LAN

Ethernet

Most widely used type of LAN

Characteristics

• Coax cable– High volume of

transmission for short distances

Characteristics

• Special hardware– Transceiver – connects

nodes to network– Interface – performs

data conversions from a byte to a series of bits

– Repeater – strengthens and retimes the signals

Characteristics

• Uses CSMA/CD– Controller – determines

when to activate communications between nodes