Relationships Among Pim Protocols - HP A8800 Configuration Manual

DR election
•
• SPT building
Neighbor discovery
PIM-SSM uses the same neighbor discovery mechanism as in PIM-DM and PIM-SM. For more information,
see "Neighbor
DR election
PIM-SSM uses a similar DR election mechanism as in PIM-SM. For more information, see
Construction of SPT
Whether to build an RPT for PIM-SM or an SPT for PIM-SSM depends on whether the multicast group the
receiver is to join falls in the SSM group range. (SSM group range reserved by IANA is 232.0.0.0/8.)
Figure 48 SPT establishment in PIM-SSM
Source
Server
As shown in
messages to the respective DRs to express their interest in the information of the specific multicast source
S.
Upon receiving a report message, the DR first checks whether the group address in this message falls in
the SSM group range:
If so, the DR sends a subscribe message for channel subscription hop by hop toward the multicast
•
source S. An (S, G) entry is created on all routers on the path from the DR to the source. Thus, an SPT
is built in the network, with the source S as its root and receivers as its leaves. This SPT is the
transmission channel in PIM-SSM.
• If not, the receiver-side DR follows the PIM-SM process. The receiver-side DR sends a (*, G) join
message to the RP, and the source-side DR registers the multicast source.

Relationships among PIM protocols

In a PIM network, PIM-DM cannot work with PIM-SM, BIDIR-PIM, or PIM-SSM. However, PIM-SM,
BIDIR-PIM, and PIM-SSM can work together. When they run together, which one is chosen for a receiver
trying to join a group depends, as shown in
discovery."
RP
SPT
Subscribe message
Multicast packets
Figure 48, Host B and Host C are multicast information receivers. They send IGMPv3 report
DR
Figure 49.
125
"DR
Host A
Receiver
DR
Host B
Receiver
Host C
election."