Preparations Before Configuring Pim-Sm - 3Com 7700 Configuration Manual

132 C 6: M
HAPTER ULTICAST
Preparations before
Configuring PIM-SM
P
ROTOCOL
Multicast Source S
Figure 10 RPT Schematic Diagram
Multicast source S
RPT
join
Multicast source
registration
Multicast Source Registration
When multicast source S sends a multicast packet to the group G, the PIM-SM
multicast router is responsible for encapsulating the packet into a registration
packet upon receipt. It then sends the packet to the corresponding RP in unicast. If
there are multiple PIM-SM multicast routers on a network segment, the
Designated Router (DR) will be responsible for sending the multicast packet.
SPT Switchover
When a multicast router detects the multicast packet with the destination address
of G from the RP is sent at a rate greater than the threshold, the multicast router
will send a join message to the node of a higher level toward the source S, which
results in switchover from the RPT to the SPT.
Configure Candidate RPs
In a PIM-SM network, multiple RPs (candidate-RPs) can be configured. Each
Candidate-RP (C-RP) is responsible for forwarding multicast packets with the
destination addresses in a certain range. Configuring multiple C-RPs is to
implement load balancing of the RP. These C-RPs are equal. All multicast routers
RPT
join
Multicast source registration
RP
RP
Receiver
Receiver