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

■ Case 2:

In this case, where receiver (x) is the last group member attached to the designated LMR, and
the first BNR connecting the designated LMR will stay a BNR after member (x) leaving the
multicast group. Figure 4.10 shows this case, where the receiver (x) will send a leavM
message to the designated LMR (M3), upon receiving this message, M3 will create and
forward RqM₁(01) message toward the source. The first BNR (N2) upon receiving this
message from (M3) it will check its MFT deciding whether it will stay a BNR or not. In this
case N2 will stay as a BNR, and will update the message by changing the S bit to zero and
forward the updated RqM₀(01) message the source. At the same time N2 will update its MFT
by removing the entry for the M3. The RqM₀(01) sent by N2 will go directly to the source
and no process will take place on this message in the intermediate IMRs or BNRs. Again, in
this case the multicast tree structure will not be changed.

Figure 4.10 Leaving process in SReM (Case 2)

■ Case 3:

In this case, shown in Figure 4.11, the BNR(N2) will not stay a BNR after receiver x leaves
the multicast group session. The existing LMR (M3) will send R_qM₁(01) message to the first
BNR(N2). Upon receiving this message N2 will check its MFT table, it realizes that M3 is
the only branch and when receiver (x) leaves, this BNR will not be a BNR any more. N2 will
send the RqM₁(10) message towards the source, and will remove the LMR entry from its

71

<<   <   82   83   84   85   86   87   88   >   >>