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

■ Investigate BNRs in the route to the destination.

■ Inform the upstream BNR of its state.

More details on DBT construction and the format of messages will be discussed later.

4.3.2 Messages and tables structure at SReM

In SReM a set of messages and one table are used to build and maintain the multicast tree.
These messages are categorized into three main types;

■ The joining and leaving messages send by new or existing members to join or leave.

■ The messages sent by LMRs on behalf of joining or leaving members

■ The messages used for updating or creating BNRs in the multicast tree.

The only table created and maintained is the Multicast Forwarding table (MFT) at the
branching nodes. In the next section a detailed description and explanation of these messages
and the MFT table.

Messages structure and signaling

As mentioned in the previous section, messages used in SReM can be divided into three
categories: - joining/leaving messages between LMRs and receivers, joining/leaving
messages on behalf of the first type from LMRs to the source and branching node messages
among BNRs include the source.

In SReM, the join/leave message is the first message for building the multicast tree, which
initiates the procedure, when a receiver wants to join the multicast group and become a
member of this group it sends a JoinM message to its LMR which is the local or closest
multicast enabled router. On the other hand, a group member wants to leave the multicast
group needs to send a LeavM message to the LMR. These messages are sent using IGMPv3
protocol. The format of these messages is discussed in [36] and explained in Figure 4.1.

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