CHAPTER 3Routing ProtocolsNodes in the ad hoc network are free to move randomly within the network region, which changes the network topology randomly or dynamically. This random movement of nodes plays an important role in the performance of routing protocols[30,31]. Considering the node mobility feature, it is essential to choose an appropriate routing protocol based on the network environment. Because nodes are mobile in nature and move randomly anywhere, so it is important to obtain a valid route between a source node and a destination node in the network[20,21,22].A protocol Routing is the set of rules that specifies that the way routers communicate with each other also provides the information that allows them to select routes between any two nodes on a computer network. A routing protocol shares this information first among immediate neighbors and then across the network. In this way, routers gain knowledge about the network topology[24,25]. The term routing protocol can specifically refer to a protocol operating at the third layer of the OSI model, which shares topological information between routers. Although there are many types of routing protocols, three main classes are used on IP networks: • Interior gateway routing via link-state routing protocols • Interior gateway routing via path vector protocols or distance vector • Exterior gateway routing is the routing protocol used by the public. Internet. Specific characteristics of routing protocols include • how they avoid routing loops • how they select preferred routes • how long they take to converge3. Classification of routing protocolsRouting protocols in MANETs can be classified into three categories...... middle of paper ......ce no2 2 1 163 2 2 324 4 1 385 5 1 457 4 2 988 2 3 1119 2 3 11810 4 3 18611 5 3 18912 5 4 192 Table 3.2 Routing table entries for node 1 after topology change Destination Next node Distance Sequence #2 2 1 163 2 2 324 4 1 385 5 1 456 5 2 8 97 4 2 988 2 3 1119 2 4 14610 4 3 18611 5 3 18912 5 4 192 When a mobile host receives new routing information (usually in an incremental packet as just described), this information is compared to the information already available in previous routing information packets. Any route with a newer sequence number is used. The metrics of the routes chosen from the newly received broadcast information are each incremented by one hop. Newly recorded routes are scheduled to be immediately announced to neighbors of the current mobile host. [5,40,41,42].