Two Network Types Defined by DISTANCE LAN WAN

NETWORKS LAN LOCAL AREA NETWORK

LAN Ethernet A particular type of LAN

Network Components (LAN) n Workstations – microcomputers – minicomputers – workstations – mainframes – terminals – supercomputers n Servers (optional) n Media n Interfaces – circuit boards – network adapter – NIC – network interface card n Gateways – connect dissimilar parts of a network n Bridges – connect similar parts of a network

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

Media - cables n Coaxial – more reliable – what is used in cable TV – harder to install – faster

Media - cables n 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: §BUS §STAR §RING

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 Software Operating system of the network

Resides on server Controls file transfers Controls hardware sharing Controls uploading/downloading of files May include: –electronic mail –performance analyzation software –security software –diagnostic 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