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Ad HoC Mobile Wireless netWorks
hops from S to I1 is 1. Considering all these, the shortest path
from R3 to the source S would be the path that goes through the
intermediate tree node I1. Hence, R3 decides to join the multicast
tree through I1 and sends a multicast activation (MACT) message
to I1. e intermediate nodes I5 and I8 that forwarded all of the
three control packets (RREQ, RREP, and MACT) now become
part of the multicast tree.
Tree maintenance phase. e tree is maintained by the expand-
ing ring search (ERS) approach, using the RREQ, RREP, and
MACT messages. e downstream node of a broken link is respon-
sible for initiating ERS to issue a fresh RREQ for the group. is
RREQ contains the hop count of the requesting node from the