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

nodes to discover providers. Some are directory-less like UPnP [2] that has a peer-to-peer
(P2P) architecture and the service information is stored on each device. The third category is
hybrid that can work in both modes, that is with or without a directory depending on the
situation. Examples of these service provide protocols are Jini [39], Universal Plug and Play
(UPnP) [2] and Salutation [19].

In this thesis, it is assumed that the receiver has discovered the service by any of the above
methods and is ready to initiate the request for joining. As part of that, it also assumed that
the receiver has obtained the necessary information required to join the multicast group by
sending the appropriate join message using IGMPv3.

As such, the scope of SReM stands as it receives the join message from the receiver and
deals with routing and joining/leaving of receivers.

In SReM, joining/leaving and BNR selection is done by using the above mentioned
signalling messages i.e JoinM, LeavM, RqM, RpM, eBNM and rBNM. These messages work
together and individually to build the multicast tree and perform the process of multicasting.
The BNR selection is part of joining and leaving process so the description of BNR selection
will be described during joining and leaving processes. In the next subsection will describe
the role of these messages.

4.4.2 Joining process in SReM

The joining process in SReM is initiated at the receivers, by a procedure that differs
depending on the structure of the existing multicast tree and from where the new receiver is
joining the session. In conclusion, there are three cases for joining process in SReM as
follows:-

■ Case 1: the new receiver is joining the multicast group through an LMR with
already joined receiver(s).

■ Case 2: the new receiver is the first receiver joining through an LMR and this
LMR is directly connected to a BNR.

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