Star Topology

A star topology is designed with each node (file server, workstations and peripherals connected directly to a central network hub or concentrator.

Data on a star network passes through the hub or concentrator before continuing to its destination. The hub or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable.

• All peripheral nodes may thus communicate with all others by transmitting to and receiving from, the central node only.
• The failure of a transmission line, that is, channel linking any peripheral node to the central node will result in the isolation of that peripheral node from all others.
• If the star central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two way transmission time, that is, to and from the central node, plus any delay generated in the central node.
• An active star network has an active central node that usually has the means to prevent echo-related problems.

The protocols used with star configurations are usually Ethernet or LocalTalk. Token Ring uses a similar topology called the star-wired ring.

1. Advantages of a Star Topology
   • Easy to install and wire.
   • No disruptions to the network when connecting or removing devices.
   • Easy to detect faults and to remove parts.
2. Disadvantages of a Star Topology
   • Requires more cable length than a linear topology.
   • If the hub or concentrator fails, nodes attached are disabled.
   • More expensive than linear bus topologies because of the cost of the concentrators.
3. Examples of Star Topology
   • ARCnet
   • 10Base-T, 100Base-TX
   • StarLAN.