Classifications of Networks-Part 3

Network Topologies

                                 A network Topology means, the physical arrangement of computers,devices and cables in a network.

Bus Topology  

In Bus topology network devices uses a common backbone in a linear shape to communicate in the network. All the devices should be attached with this single shared cable with an interface connector. The device, which wants to communicate send a broadcast message to all the devices attached with the shared cable but only the intended recipient will accepts and process that message.

Bus Topology

Advantages

1. Easy to setup a network.
2. Easy to expand.
3. Suited topology for small networks.
4. Less expensive compared to other topologies.                                  

Disadvantages

1.  Slower data transfer rate.
2. Cable length and number of nodes that can connected are limited.
3. If the backbone cable fails, the whole network will fails.
4. Heavy network traffic when number of nodes are increased.

Ring Topology 

Ring Topology

In this topology computers are arranged in a ring manner. That is every computer or devices in this network should have two neighbors for communication. All the communications will be in the same direction, either clockwise or anti-clockwise. 

                              FDDI (Fiber Distributed Data Interface) or Token Ring Technology can be used to implement Ring Technology. Ring topologies can be found in office, school or small buildings.

Advantages

1. Chances of collision is very low.
2. Better performance than a Bus topology.

Disadvantages

1. Failure of one computer or port can cause the whole network to fail.
2. Adding, moving or removing devices can affect the network.
3. Slower than Star topology under normal load.
4. It is difficult to troubleshoot a ring network.
5. Network cards are expensive compared to Ethernet cards and hubs.

Mesh Topology

Mesh Topology

In a mesh topology, each device in the network are interconnected to one another to provide an almost always up network connectivity. That is each device remains in the network even if one or two of the connections go down. As this topology is difficult and expensive to configure, it is not commonly used in most computer networks.

Advantages

1. Data can be transmitted from one node to many nodes and vice versa simultaneously.
2. Less traffic problems.

Disadvantages

1. Configuration of network is complex and expensive.
2. Difficult to manage the network.

Star Topology

Star topology is the most commonly used topology in LAN. A star topology links the computers by individual cables to a centralized connectivity device, usually a hub or switch. The commonly used cable is the Unshielded Twisted Pair (UTP) or Shielded Twisted Pair (STP).

Star Topology

Advantages

1. Easy to setup and expand the network. 
2. Adding, moving or removing devices will not affected to the entire network.
3. Better performance than other topologies.                  
4. Failure of one device or link will not affect the whole network.
5. Centralization of network will help to analyze the traffic.
6. Easy to troubleshoot.

Disadvantages

1. Dependency to the central device(Hub or Switch) is the main drawback. If it fails, the entire network goes down.
2. Expansion and performance of the network is depended on the capacity of the central device.
3. Need of the expansion devices(Hubs, Switches or Routers) will make the network expensive.