Wireless Routing Protocol - Method

Method

Each node implementing WRP keeps a table of routes and distances and link costs. It also maintains a 'message retransmission list' (MRL).

Routing table entries contain distance to a destination node, the previous and next nodes along the route, and is tagged to identify the route's state: whether it is a simple path, loop or invalid route. (Storing the previous and successive nodes assists in detecting loops and avoiding the counting-to-infinity problem - a shortcoming of Distance Vector Routing.)

The link cost table maintains the cost of the link to its nearest neighbors (nodes within direct transmission range), and the number of timeouts since successfully receiving a message from the neighbor.

Nodes periodically exchange routing tables with their neighbors via update messages, or whenever the link state table changes. The MRL maintains a list of which neighbors are yet to acknowledged an update message, so they can be retransmitted if necessary. Where no change in the routing table, a node is required to transmit a 'hello' message to affirm its connectivity.

When an update message is received, a node updates its distance table and reassesses the best route paths. It also carries out a consistency check with its neighbors, to help eliminate loops and speed up convergence.