What is the network topology? Describe different types of topologies & advantages and disadvantages with diagram.
The physical layout of devices on a network.
There are four basic topologies.
1. Mesh 2. Star 3. Bus 4. Ring
1. MESH TOPOLOGY:
In Mesh topology every device has a dedicated point to point link to every other device.
As this topology contains multiple physical link, to find the number of physical links on a mesh topology network.
If we have n number of nodes then the links will be n-1
So if there are 5 nodes (5-1) 4 links will be required for each nodes.
Advantages of Mesh topology
1. Data can be transmitted from different devices simultaneously. This topology can withstand high traffic.
2. Even if one of the components fails there is always an alternative present. So data transfer doesn’t get affected.
3. Expansion and modification in topology can be done without disrupting other nodes.
Disadvantages of Mesh topology
1. There are high chances of redundancy in many of the network connections.
2. Overall cost of this network is way too high as compared to other network topologies.
3. Set-up and maintenance of this topology is very difficult. Even administration of the network is tough.
2. STAR TOPOLOGY:
In star topology each device has dedicated point to point link only to a central controller usually called a hub.
Advantages of Star Topology
1. Easy to connect new nodes or devices. In star topology new nodes can be added easily without affecting rest of the network. Similarly components can also be removed easily.
2. As compared to Bus topology it gives far much better performance.
3. Failure of one node or link doesn’t affect the rest of network. Easy to detect faults and to remove parts.
Disadvantages of Star Topology
1. Requires more cable length than a linear topology.
2. Too much dependency on central device has its own drawbacks. If it fails whole network goes down.
3. More expensive than linear bus topologies because of the cost of the hubs, router or switch etc.
4. Performance and as well number of nodes which can be added in such topology is depended on capacity of central device.
3. BUST TOPOLOGY:
In Bus topology all devices are connected via a single link. One long cable acts as a backbone to link all the devices in a network.
Advantages Bus Topology
1. It is easy to set-up and extend bus network.
2. Requires less cable length compared to other networks.
3. Bus topology costs very less.
4. Linear Bus network is mostly used in small networks. Good for LAN.
Disadvantages Bus Topology
1. Efficiency of Bus network reduces as the number of devices connected to it increases. There is a limit on central cable length and number of nodes that can be connected.
2. Entire network shuts down if there is a break in the main cable (backbone cable).
3. Proper termination is required to dump signals. Use of terminators is must.
4. It is difficult to detect and troubleshoot fault at individual station.
5. Maintenance costs can go higher with time.
6. It is not suitable for networks with heavy traffic.
7. Security is very low because all the computers receive the sent signal from the source.
4. RING TOPOLOGY:
In this topology the nodes are connected in a way that they form a ring shape.
Each device is linked to only its immediate neighbors. A signal is passed along the ring in one direction from device to device.
We can have a main star topology with each branch connecting several stations (devices) in a bus topology.
Advantages of Ring Topology
1. Each node sends the data when it receives an empty token. This helps to reduces chances of collision.
2. Even when the load on the network increases, its performance is better than that of Bus topology.
3. Additional components do not affect the performance of network.
4. Each computer has equal access to resources.
Disadvantages of Ring Topology
1. Each packet of data must pass through all the computers between source and destination. This makes it slower than Star topology.
2. A failure in any cable or device breaks the loop and can take down the entire network.
3. Network is highly dependent on the wire which connects different components.
4. MAU’s and network cards are expensive as compared to Ethernet cards and hubs.