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

Normalized routing overhead

Figure 4.28 shows the normalized overhead as a function of group size. It can be noticed that
SReM has got constant values even when the group size grows. This is because the joining
procedure of new members is done locally in BNRs and the source is informed of this join as
discussed in Section 4.4.2. In Xcast+ the values of overhead are higher than values in SReM
because in Xcast+ the overhead messages for joining new members must reach the source
which will increase the routing overhead in the network.

Figure 4.28 Normalized Routing Overhead (Load).

4.7 Summary

In this chapter a new scalable recursive multicast protocol (SReM) is proposed and a
performance analysis study is done. SReM is a recursive multicast protocol, which uses a
recursive unicast scheme to build the multicast tree. SReM also improves the scalability issue
by dynamically selecting multicast enabled nodes to be a Branching Node Routers (BNRs) in
order to take part of joining /leaving and data forwarding responsibility.

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