Design and investigation of scalable multicast recursive protocols for wired and wireless ad hoc networks

Vector (DSDV) [53], Optimized Link State Routing (OLSR) [40], and Source Tree Adaptive
Routing Protocol (STAR) [29]. This section describes a number of proactive routing
protocols.

2.4.2.1 Destination Sequence Distance Vector (DSDV) protocol

The Destination Sequence Distance Vector (DSDV) [53] is a hop-by-hop proactive unicast
routing protocol where each node maintains a routing table. Like distance vector, DSDV
keep the entries of the routing table fresh by periodically broadcast routing updates. The
main advantage of DSDV over traditional distance vector protocols is being loop free
protocol.

In each node the routing table in DSDV protocol stores entries for all reachable destinations
for the designated node, each entry consists of next hop, a number of hops for that destination
and a sequence number created by the destination. Sequence numbers in DSDV protocol,
used to show the freshness of routes in the routing table for the destinations and guarantee the
loop free feature in DSDV.

The route updates of DSDV can be either time-driven or event-driven. In time-driven every
node periodically transmits updates including its routing information to its immediate
neighbours. Whereas in event-driven updates, a node detects significant changes in its route
information from the last update it sends an update for the routing information in an event-
triggered style.

As previously explained, DSDV is a distance vector with some adjustments to be suitable for
ad hoc use. These adjustments are the use of event-triggered update among the broadcast
(time-event) updates. Moreover, DSDV uses two types of update messages: full dump and
incremental dump. A full dump message carries all information available for update, where
incremental dump message carries only the information about routes which their metrics
changed from the last update.

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