Meaning of Network Topology: The topology of a network is the structure defined by the interconnection scheme. This structure can be viewed as a graph with vertices representing the switching nodes and the branches representing the transmission channels. The choice of topology involves many interrelated factors:
1. Expected traffic.
2. Routing method.
3. Channel capacity.
Types of Network Topology: The various topologies are
1. Mesh Topology
2. Ring Topology
3. Bus Topology
4. Tree Topology
5. Star Topology
1. Mesh Topology: In this type of structure, each node is directly connected to every other node. Each device has a point-to-point link with each other device. This topology provides alternative routes between nodes. A very large wire length is required and cost may become too high to be justified. Public and private data communication networks use this kind of topology. It is also known as fully connected topology.
2. Ring Topology: In this topology, the host computer and workstation are connected in series forming a complete ring for data communication. The links are unidirectional (clockwise/anticlockwise). It is economical and no collision of data takes place between two workstations. The problem arises while adding new devices in the networking series. It is used in LANs.
3. Bus Topology: In this kind of structure, there is no central host computer. There is a single data cable which is shared by the workstations. It allows flexible networking as devices can be easily attached. It is economical because the single cable is involved but the possibility of data collision occurs.
4. Tree Topology: It is also known as hierarchical or vertical network. There may be more than one central nodes as it follows tree-like architecture. If one centre fails, the network can continue to be partially operational. This kind of structure is used in remote access networks.
5. Star Topology: In this, different workstations are connected by cables with the centrally located host computer known as server or HUB. The server is responsible for routing traffic and fault isolation. The failure of workstation does not affect structure, but a failure of the centrally located host computer, HUB causes a complete breakdown of the communication network.