Routing Protocols in MANETs


Hope you are familiar with the term routing. We need to find a path from a source to the destination in the network to forward the packets. Finding the best possible path is often a matter of question here. We need to find a path with minimum packet loss, energy requirements and other costs.

Apart from the customary routing techniques, the MANET routing techniques are different as each individual node can act as a router and host. Thus the level of security is compromised for MANETs.


Routing Protocols in MANETs

In MANETs, the routing protocols can be categorized as:

  • Table-driven (Proactive)
  • On-demand (Reactive)
  • Hybrid

Table-driven protocols include DSDV (destination sequenced distance vector) and OLSR protocol whereas AODV and DSR are the examples of On-demand routing protocols.


Proactive protocols:

  • Routing information is stored in the roting table and occasionally altered when there is topology change.
  • This protocol is not preferred for networks with large number of nodes as it is difficult to maintain routing information of each node in each node’s routing table.

Table-driven routing protocols maintain a routing table and find the route in advance. It exchanges routing information occasionally to preserve the route.

But reactive routing protocols find a route only when it is required. Whenever there is a path failure, an optional route is chosen.

Let us consider the case of a reactive routing protocol (AODV) and check the possible route of a route reply packet (RREP) from a destination to a source. Here the node A need to set up a route to node J.

  1. To establish the route, A needs to broadcast RREQ packet to all the other neighboring nodes in the network.
  2. When node J receives the RREQ packet, it sends back a RREP packet.
  3. This packet is unicasted to the sender node (ie A) through the other neighboring nodes.





For more information on MANET, read on MANET characteristics.