1.3 PROACTIVE ROUTING PROTOCOLS
Proactive routing protocols try to collect as much information about the MANET as possible through proactive exchange of messages about their local topology. One of the earliest protocols for MANETs was the destination sequenced distance vector (DSDV) protocol , which is one of the best known proactive routing protocols. The DSDV protocol has a large overhead of control messages and hence it fell out of favor due to the emergence of more efficient reactive protocols such as the dynamic source routing (DSR) and the ad hoc on-demand distance vector (AODV) protocol. However, the low latency in packet delivery is one of the most attractive aspects of the proactive protocols. Considerable work has been done in recent years to reduce the overhead of the DSDV protocol and one of the most promising proactive protocols called the optimal link state routing (OLSR) protocol  is currently under consideration by the MANET working group. In this section, we will first discuss the DSDV protocol and then the OLSR protocol.
1.3.1 The Destination Sequenced Distance Vector Protocol
We should first list a few points about MANET routing protocols that are applicable for all the protocols discussed in this chapter. A routing protocol is a distributed algorithm executed by each node in a MANET. In other words, each node executes a local copy of the protocol on the data that they collect locally. Moreover, this distributed execution of a protocol aims to achieve ...