Bus Topology

• 
  all workstations connect to the same cable segment


• 
  commonly used for implementing Ethernet at 10mbps


• 
  the cable is terminated at each end


• 
  wiring is normally done point to point


• 
  a faulty cable or workstation will take the entire LAN down


• 
  two wire, generally implemented using coaxial cable during the 1980's

The bus cable carries the transmitted message along the cable. As the message arrives at each workstation, the workstation computer checks the destination address contained in the message to see if it matches it's own. If the address does not match, the workstation does nothing more.
If the workstation addresses matches that contained in the message, the workstation processes the message. The message is transmitted along the cable and is visible to all computers connected to that cable.

There are THREE common wiring implementations for bus networks

• 
  10Base2 -(thin-net, Cheaper Net) 50-ohm cable using BNC T connectors, cards provide transceiver


• 
  10Base5-(Thick Net) 50-ohm cable using 15-pin AUI D-type connectors and external transceivers


• 
  10BaseT- (UTP) UTP cable using RJ45 connectors and a wiring centre
  
  
  
  The above diagram shows a number of computers connected to a Bus cable, in this case, implemented as Thin Ethernet. Each computer has a network card installed, which directly attaches to the network bus cable via a T-Connector.
  It is becoming common to use 10BaseT (UTP) for implementing Ethernet LANS. Each workstation is wired in star fashion back to a concentrator wiring centre (hub). The hub is a multi-port device supporting up to about 32 ports. One of these ports is connected to a server, or the output of the hub can be connected to other hubs.