Reactive and Proactive Protocols are the routing protocols that are used in mobile Ad hoc networks to send data from the host to the destination. A packet data is sent from source to destination in an Ad hoc network through multiple nodes that are mobile. This type of network is generally used in a disaster hit area, military field or in space where fixed infrastructure is destroyed or does not exist. The nodes of this network work as the routers to the packet data and transmit it from one node to another till the destination. These nodes are mobile and can be located on ship, car, bus or aero plane. As the data has to pass several nodes before getting delivered a routing protocol is must so that data can be passed from one node to another and delivered to the correct address. Routing protocols are classified into six categories according to the way they perform their work and we will discuss two of them Reactive and Proactive Protocols.
There are two types of Reactive protocols Ad hoc On-Demand Distance Vector or AODV and Temporary Ordering Routing Algorithm or TORA. In AODV routing protocol the node work independently and does not carry the information of nodes adjacent to it or the information of the other nodes in the network. They work only when a data is delivered to them so as to maintain the route to the destination. These nodes have the information of the route through which data has to be delivered so they pass the packet to the next node in predetermined route. TORA is a very efficient and adaptive algorithm as it works up all the shortest possible routes from source to destination. This protocol is able to ensure the creation of route, journey of the data and erase the route in case there is partition in the network. In this protocol every node carries the information of its neighboring nodes.
This protocol uses Destination Sequence Distance Vector or DSDV router designed with Bellmann-Ford algorithm. In this protocol all the nodes maintain the information about the next node. All the mobile nodes of this protocol have to relay its entries to its adjacent nodes. The nodes that lay in the route pass the packet data from one node to the other node after mutual agreement therefore all the nodes must constantly update their position in DSDV protocol so that there is no interruption in the route.
Proactive vs Reactive Protocols
• Average end-to-end delay or the time taken by the data to reach the destination from the source is variable in Reactive Protocols but remains constant in Proactive Protocols for a given Ad hoc network.
• The delivery of packet data is much more efficient in Reactive Protocols than in Proactive Protocols.
• Reactive Protocols are much faster in performance than Proactive protocols.
• Reactive Protocols are much more adaptive and work much better in different topographies than Proactive Protocols.