Network Topology Bus, ring and star

The term topology refers to the way a network is laid out, either physically or logically. Physical topology refers to the placement of the network's various components, including device location and cable installation, while logical topology shows how data flows within a network, regardless of its physical design. We will briefly discuss various topologies of LAN.

Bus Topology

Bus topology is an implementation of broadcast networks. In bus topology, a single long cable acts as a backbone to link all devices in the network.

Bus topology                           

The two endpoints of the common transmission cable or medium are usually terminated with a device called a terminator that exhibits the characteristic impedance of the transmission medium.  At any one instance, one node is the master and is allowed to transmit, rest are required to cease from sending. Bus networks use carrier sense multiple access (CSMA) to deal with multiple senders.

Advantages

·        Ease of installation

·        Cheap and simple

·        Uses less cables

Disadvantages

·        Difficulty in fault tolerance and reconfiguration.

·        A break in the cable stops all transmissions.

Ring Topology

   In ring topology, each node has a dedicated point-to-point connection only with the two nodes in either side of it. A message or signal is passed along the ring in one direction, from device to device, until it reaches its destination.

Ring Topology

Advantages

·        Easy to install and reconfigure

·        Fault isolation is simplified

·        Perform better than bus topology under heavy load

 Disadvantages

·        Unidirectional traffic

·        A break in the ring can disable the entire network

Star Topology

Star networks are the most common LAN topology. In a star topology, each device has a dedicated link inly to a central controller, usually the hub. All data exchange between devices take place through hub.

Star topology

 Advantages

·        Better performance

·        Isolation of devices

·        Benefits from centralization

Disadvantage of the star topology is that if the central controller fails, the entire network goes down with it.

Next :  Network typologies tree and mesh

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