Network Topologies

Topology

Topology refers to the interconnection of paths between the many users or nodes and how they are arranged or it refers to physical layout of the network in which all devices are connected.

Thus, topology means a topographic study of a specific object, entity, place etc.

Different topologies are used in computer network i.e.

1. Bus Topology
2. Star Topology
3. Ring Topology
4. Intersecting Rings Topology
5. Mesh Or Complete Topology
6. Hybrid Topology
7. Tree Topology

Bus Topology

In this topology, all nodes are connected with single communication medium/channel. One machine act as a transmitter and other act as a receiver, normally co-axial cable acts as a transmitter for BUS. In this, data flow in either direction i.e. if a message goes in channel, it reaches every node and if it matches it accept the message otherwise discards it. All nodes share the co-axial cable.

Thus, Bus is flexible structure because users can put anywhere along its length and at low costs and less difficulty.

But, the biggest limitation with Bus requires more management because needs protocols which decide which node became a transmitter. Second if channel breaks, anywhere then some nodes stops functioning at all. Third, it is very weak in terms of security.

Star Topology

In this topology, there is central node and all PC’s or users communicate via central node. There is no limit in the number of users, which are attached to central node. Thus, reliability is higher.

Suppose, one user wants to sends data message to other in this topology, then the sender makes number of copies according to number of users in Star Topology and reaches to everyone.

This topology is used in telephone system and used when more than one pair of users send data at same time. Thus, central nodes provide multiple path ways.

Thus, reliability is higher because problem in one computer does not affect the other users.

Ring Topology

In Ring Network Topology, each node/station is connected to its upstream neighbour and downstream neighbour. Thus, in this each node receive data from previous node and repeats the information to next node. Thus, information flows from originating node, through all other nodes and back to origin node.

IBM Token-Ring & Fiber Distributed Data Interface (FDDI) is two of ring-type networks. Ring Network has the same efficiency of cabling as the Bus Network.

Intersecting Rings Topology

All routers of one ring are connected with all the other routers of second ring via intersecting router i.e. all computers of a ring are connected to other computers of second ring via intersecting server.

If intersecting server fails, then computers of first ring fails to communicate with computers of second ring.

Mesh or Complete Topology

Any computer is directly linked with all other computers in the network through direct lines.

In a true mesh topology every node has a connection with every other node in the network. The main advantage is that failure of any computer does not effect the functioning of other computers and no node will ever encounter a busy channel when trying to communicate with another node.

`The disadvantage is that when number of nodes goes up. The number of connections increases almost exponentially. This requires more cabling, thus very expensive.

Hybrid Topology

There is no specified links between any two users some users communicate through direct lines and some follows store-and-forward principle. Mixture of all these common network topologies is Hybrid Topology.

This topology can have Ring or Bus or Star on one side and another at other side. It uses point-to-point lines to tie them both together.

Tree Topology

Any user can communicate to any other user through Tree Topology.