use the multicast tree control plane based on Multicast Control Table(s) (MCTs) in no-
branching node routers(non-BNRs). Due to this fact, REUNITE and HBH suffer from the
massive control messages traffic due to the use of this extra multicast control table (MCT) at
all of non-branching nodes in addition to MFT in BNRs. This is because the number of
BNRs usually is far less than the number of non-BNRs, given a multicast group, only less
part of multicast routers takes part in the multicast session in SReM, while all multicast
routers are involved in the multicast session in HBH or REUNITE. Therefore, from this
scalability point of view, the advantage of our proposed scheme SReM is remarkable
compared with HBH and REUNITE.
An additional disadvantage, REUNITE introduces dynamic behaviours such as tree
restructuring, race condition of joins and duplicates packets during tree restructuring.
However, these problem will not be found in SReM due to the use of DBT multicast
mechanism.
Another significant difference between our proposed SReM, HBH and REUNITE is that in
SReM the join/leave message is sent only when a new member of multicast group join or an
existing member leave, while both REUNITE and HBH needs periodically sending JOIN and
TREE messages, using as a timer for each entry in MFTs. Furthermore, HBH need to
introduce new FUSION message. Obviously, these operations result in remarkable control
messages traffic across networks. However, in SReM there is no remarkable control
message traffic like REUNITE and HBH.
SReM, however, aims to overcome these disadvantages in SEM. In SReM, the format of
BNMs is changed. Instead of all of destinations of a multicast session, only one BNR and
one newly-joining destination are encoded in the BNMs, as discussed previously in this
chapter. As a result, the BNMs have a flat size regardless of the size of the multicast group.
Therefore, SReM is scalable.
On the other hand, in SReM, the multicast source is in charge of the registration process but
rarely takes part in the building of the multicast tree. In fact, the source takes part in the set-
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