Explain about LAN topologies.

q)Explain about LAN topologies.


When we go for networking, we connect some computers in particular layout or design. This design or pattern of connection is called topology.
There are many types;
Bus topology:
A linear bus topology consists of a main run of cable with a terminator at each end (See fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear cable.

Fig. 1. Linear Bus topology

Advantages of a Linear Bus Topology

  • Installation is easy and cheap to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

  • Entire network shuts down if there is a break in the main cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution in a large building.

Star topology:-

  • A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator (See fig. 2).
  • Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, 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.

              Fig. 2. Star topology

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.

Disadvantages of a Star Topology

  • Requires more cable length than a linear topology.
  • If the hub, switch, or concentrator fails, nodes attached are disabled.

Mesh topology
  • The mesh topology incorporates a unique network design in which each computer on the network connects to every other, creating a point-to-point connection between every device on the network. The purpose of the mesh design is to provide a high level of redundancy.
  • It needs/uses n(n-1)/2 channels(paths) and n-1 input/ output ports.
  • If one network cable fails, the data always has an alternative path to get to its destination. Figure 6 shows the mesh topology.
  • As you can see from Figure 6, the wiring for a mesh network can be very complicated.
  • It is used mostly in telephone network.This allows computer to balance the load by providing alternative paths. It creates a redundant point-to-point network connection between only specific network devices.

Figure 6. Mesh topology.

Provides redundant paths between devices
Requires more cable than the other LAN topologies.
The network can be expanded without disruption to current users.
more devices needed.

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