Prerequisite – Classification of Routing Algorithms
Distance Vector Routing –
- It is a dynamic routing algorithm in which each router computes a distance between itself and each possible destination i.e. its immediate neighbors.
- The router shares its knowledge about the whole network to its neighbors and accordingly updates the table based on its neighbors.
- The sharing of information with the neighbors takes place at regular intervals.
- It makes use of Bellman-Ford Algorithm for making routing tables.
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Problems – Count to infinity problem which can be solved by splitting horizon.
– Good news spread fast and bad news spread slowly.
– Persistent looping problem i.e. loop will be there forever.
Link State Routing –
- It is a dynamic routing algorithm in which each router shares knowledge of its neighbors with every other router in the network.
- A router sends its information about its neighbors only to all the routers through flooding.
- Information sharing takes place only whenever there is a change.
- It makes use of Dijkstra’s Algorithm for making routing tables.
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Problems – Heavy traffic due to flooding of packets.
– Flooding can result in infinite looping which can be solved by using the Time to live (TTL) field.
Comparison between Distance Vector Routing and Link State Routing:
Figure:- Distance Vector Routing Vs Link State Routing
| S.No. | Distance Vector Routing | Link State Routing |
|---|---|---|
| 1. | Bandwidth required is less due to local sharing, small packets and no flooding. | Bandwidth required is more due to flooding and sending of large link state packets. |
| 2. | Based on local knowledge, since it updates table based on information from neighbours. | Based on global knowledge, it have knowledge about entire network. |
| 3. | Make use of Bellman Ford Algorithm. | Make use of Dijakstra’s algorithm. |
| 4. | Traffic is less. | Traffic is more. |
| 5. | Converges slowly i.e, good news spread fast and bad news spread slowly. | Converges faster. |
| 6. | Count of infinity problem. | No count of infinity problem. |
| 7. | Persistent looping problem i.e, loop will be there forever. | No persistent loops, only transient loops. |
| 8. | Practical implementation is RIP and IGRP. | Practical implementation is OSPF and ISIS. |
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