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

through the tree without any loops or duplicates transmission. The subsections will provide
brief description of the most popular tree-based multicast ad hoc routing protocols.

2.4.6.1 Multicast Ad hoc On-demand Distance Vector protocol (MAODV)

MAODV [57] is a multicast extension of the AODV [54] routing protocol. MAODV follows
the way AODV establishes the unicast route with multicast capabilities. MAODV is a tree-
based algorithm, so it establishes a shared tree to connect the group members. Each multicast
group has a group leader taking responsibility for establishing and maintaining a destination
sequence number and broadcasting a (Grp-Hello) message periodically to maintain the group
members connected.

Building a tree at MAODV is done incrementally and in a receiver-initiated way. If a node
needs to join a multicast group, it initiates and propagates RREQ message with joined flag
set. A node within the same group that has a valid route to the destination will send back a
RREP message and inform the group leader with the information about the new node. The
prospective node that sent the RREQ may receive more than one RREP, so the RREP
message with the highest sequence number and minimum number of hops will be selected.
This process will ensure that the new member is added without any loop. Figure 2.8 shows
the operations of adding a prospective node to a group using MAODV protocol.

Figure 2.8 Node Join operation in MAODV [64].

26

<<   37   38   39   40   41   42   43   >>

More intriguing information