Difference between AODV and DSR algorithm?

Answer 1

Ad hoc distance vector routing and dynamic source routing are the two major routing protocols used in Ad-hoc mobile networks . An Ad-hoc network is the cooperative engagement of mobile nodes without the required intervention of any centralised access point or infrastructure.Local caches are maintained to facilitate the routing.

Differences between AODV and DSR are as follows

1) All the routing information for the path that is to be taken from the source to the destination in DSR is included in the header of the request where as in AODV each node maintains a routing table that contains routing information to all the nodes in the network.

2) If any link failure occurs in the network , DSR send a unicast packet to the source giving the information about the broken link where as AODV broadcast the Route error message to all its neighbors as it is possible that the revrse path from the problematic node to the source has timed out.

3) Stale caches(Caches with information that are outdated or broken) can cause problem in routing(as cycles).In DSR this problem is solved by stopping the response from the intermediate host if the reply packet causes a loop formation .This restriction also makes the intermediate host reply from its local cache, only when the host is present in the end of the route request packet and at the start of the route in its local cache

AODV handles this problem by maintaining a sequence number in the route table.This sequence number corresponds to the freshest route available to the destination.More the sequence number fresher is the route.So now if the link fails,the node which was joined to the link and the network broadcast a route error with increased sequence number.SO no node which has lesser sequence number than the received sequence number will respond using its local cache.