Gugrajah_Yuvaan_ Ramesh_2003.pdf

Routing Protocols for Ad Hoc Networks Chapter 2
were proposed for routing in ad hoc networks were proactive distance vector
protocols based on the Distributed Bellman Ford (DBF) algorithm [Bertsekas92].
However, the DBF algorithm suffers from poor convergence and high control traffic
overhead. The DBF algorithm was therefore modified to overcome these problems
which resulted in protocols such as the Destination Sequenced Distance Vector
(DSDV) algorithm [Perkins94]. Link state protocols were also applied to address the
convergence problem resulting in protocols such as the Optimized Link State
Routing Protocol (OLSR) [Jaquet98]. The Wireless Routing Protocol (WRP)
[Murthy95] is an example of a path finding algorithm with combines the features of
the distance vector and link state approaches. The path finding algorithms attempt to
reduce the amount of control traffic, reduce the possibility of temporary routing
loops, and avoid the "counting-to-infinity" problem.
2.2.1.1. DSDV
In the Destination-Sequenced Distance-Vector (DSDV) routing protocol [Perkins94]
each node maintains two tables. The routing table contains a list of all possible
destinations in the network, the number of hops to each destination, the next hop and
the route sequence number. Routing table updates are periodically transmitted
throughout the network by each of the nodes. Nodes also transmit routing updates if
they become aware of significant changes in the topology. Routing table updates are
therefore both time-driven and event-driven. The route updates can be one of two
types to reduce the potentially large amount of network traffic that can be generated.
The "full dump" results in all available routing information from a node being
transmitted to its neighbours and is performed infrequently when topological changes
are occurring slowly. In an "incremental update", only information that has changed
since the last full dump is transmitted. The second table that is maintained stores the
data received in the incremental routing information packets.
DSDV improves the DBF algorithm by including sequence numbers in the routing
updates that eliminate route looping by identifying stale routes. The sequence
number for a route is assigned by the destination node and is increased by one for
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