Most secure updating routing information
A full dump sends the full routing table to the neighbors and could span many packets whereas in an incremental update only those entries from the routing table are sent that has a metric change since the last update and it must fit in a packet.
If there is space in the incremental update packet then those entries may be included whose sequence number has changed.
When it goes out of range of one base station, it connects with new base station and starts communicating through it. All nodes of these networks behave as routers and take part in discovery and maintenance of routes to other nodes in the network.
Ad hoc networks are very useful in emergency search-and-rescue operations, meetings or conventions in which persons wish to quickly share information, and data acquisition operations in inhospitable terrain [Royer99].
Each route update packet, in addition to the routing table information, also contains a unique sequence number assigned by the transmitter. The stations delay the transmission of a routing update by settling time so as to eliminate those updates that would occur if a better route were found very soon.
The Wireless Routing Protocol (WRP) [Murthy96]is a table-based distance-vector routing protocol.
The ad hoc routing protocols can be divided into two classes :- table-driven and on-demand.The Link-Cost table contains cost of link to each neighbor of the node and the number of timeouts since an error-free message was received from that neighbor.The Message Retransmission list (MRL) contains information to let a node know which of its neighbor has not acknowledged its update message and to retransmit update message to that neighbor.When the network is relatively stable, incremental updates are sent to avoid extra traffic and full dump are relatively infrequent.In a fast-changing network, incremental packets can grow big so full dumps will be more frequent. If two routes have the same sequence number then the route with the best metric (i.e. Based on the past history, the stations estimate the settling time of routes.