Distance vector routing algorithm:
- Distance vector routing is a dynamic routing algorithm where each router maintains a routing table (vector) containing the best known distance to each destination and the link to use to reach that destination.
- The routing tables are updated by exchanging information with neighboring routers. Each router shares its routing table with its neighbors, allowing them to update their own routing information.
- It is also known as the distributed Bellman-Ford routing algorithm, named after the researchers who developed it.
- In distance vector routing, each router’s routing table entry for a destination contains two parts: the preferred outgoing link to use for that destination and an estimate of the distance (e.g., hop count or propagation delay) to that destination.
- Routers periodically send their estimated distances to each destination to their neighbors. Upon receiving this information, a router can calculate the distance to reach each destination via each neighbor and update its routing table with the best (shortest) path.
- The algorithm is illustrated with an example network, showing how a router (J) updates its routing table based on the delay vectors received from its neighbors (A, I, H, K).
- For each destination, the router calculates the total distance through each neighbor by adding the neighbor’s advertised distance and the cost to reach that neighbor. It then selects the path with the shortest total distance and updates its routing table accordingly.
- The distance vector routing algorithm was the original ARPANET routing algorithm and was also used in the Internet under the name RIP (Routing Information Protocol).
