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

Figure 2.4 Route request propagation in DSR [58]

Figure 2.4 describes an example of route request in DSR. The source N1 needs to find a route
for the destination N8. This route is not available in the source cache, so it propagates a route
request message in the network. The intermediate nodes (N2 to N7) rebroadcast the message,
during the rebroadcast each message adapt its address in the path toward the destination.
Finally, the destination will receive the route request message from its neighbours; each route
request contains a list of intermediate nodes which represent the path from the source. The
destination N8 will select the shortest paths (minimum number of hops). The route request
message contains the source address, the destination address and a unique identification
number. The later found at route request message limits the number of message propagation
in the intermediate nodes, which processes the route request if it has not been seen before,
which at the end will reduce the rebroadcasting of route request message.

Whenever the route discovery is successful (Reached the destination or an intermediate node
has a valid route to the destination), the source will receive a route reply message, which
contains a list of intermediate nodes addresses by which the destination is reachable.

The route reply is generated by an intermediate node which has a valid route to the
destination or by the destination itself. If the route reply is generated by the destination then
the contents of route request message is placed in the route reply message. On the other hand,

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