Destination-Sequenced Distance-Vector Routing (DSDV) is a table-driven routing scheme for ad hoc mobile networks based on the

Bellman–Ford algorithm The Bellman–Ford algorithm is an algorithm that computes shortest paths from a single source vertex to all of the other vertices in a weighted digraph. It is slower than Dijkstra's algorithm for the same problem, but more versatile, as it is ...

. It was developed by C. Perkins and P. Bhagwat in 1994. The main contribution of the algorithm was to solve the

routing loop problem A routing loop is a common problem with various types of networks, particularly computer networks. They are formed when an error occurs in the operation of the routing algorithm, and as a result, in a group of nodes, the path to a particular destin ...

. Each entry in the routing table contains a sequence number, the sequence numbers are generally even if a link is present; else, an odd number is used. The number is generated by the destination, and the emitter needs to send out the next update with this number. Routing information is distributed between nodes by sending ''full dumps'' infrequently and smaller incremental updates more frequently. For example, the routing table of Node A in this network is Naturally the table contains description of all possible paths reachable by node A, along with the next hop, number of hops and sequence number.

Selection of Route

If a router receives new information, then it uses the latest sequence number. If the sequence number is the same as the one already in the table, the route with the better metric is used. Stale entries are those entries that have not been updated for a while. Such entries as well as the routes using those nodes as next hops are deleted.

Advantages

The availability of paths to all destinations in network always shows that less delay is required in the path set up process. The method of incremental update with sequence number labels, marks the existing wired network protocols adaptable to Ad-hoc wireless networks. Therefore, all available wired network protocol can be useful to ad hoc wireless networks with less modification.

Disadvantages

DSDV requires a regular update of its routing tables, which uses up battery power and a small amount of bandwidth even when the network is idle. Whenever the topology of the network changes, a new sequence number is necessary before the network re-converges; thus, DSDV is not suitable for highly dynamic or large scale networks. (As in all distance-vector protocols, this does not perturb traffic in regions of the network that are not concerned by the topology change.)

Influence

While DSDV itself does not appear to be much used today, other protocols have used similar techniques. The best-known sequenced distance vector protocol is AODV, which, by virtue of being a reactive protocol, can use simpler sequencing heuristics. Babel is an attempt at making DSDV more robust, more efficient and more widely applicable while staying within the framework of proactive protocols.

References

*{{cite journal , author1=Perkins, Charles E. , author2=Bhagwat, Pravin , title = Highly Dynamic Destination-Sequenced Distance-Vector Routing (DSDV) for Mobile Computers , year = 1994 , url = https://www.cse.iitb.ac.in/~mythili/teaching/cs653_spring2014/references/dsdv.pdf , accessdate = 2006-10-20 Ad hoc routing protocols