Preparations Before Configuring Pim-Sm - Huawei Quidway S3500 Series Operation Manual

Operation Manual - Multicast
Quidway S3500 Series Ethernet Switches
receives the packets sent to multicast group G, the packets will be sent to leaf routers
along the path built and then reach the hosts. In this way, an RP-rooted tree (RPT) is
built as shown in the following figure.
Multicast Source S
Figure 7-1 RPT schematic diagram
II. Multicast source registration
When multicast source S sends a multicast packet to the multicast group G, the
PIM-SM multicast router directly connected to S will encapsulate the received packet
into a registration packet and send it to the corresponding RP in unicast form. If there
are multiple PIM-SM multicast routers on a network segment, the Designated Router
(DR) will be responsible for sending the multicast packet.
III. SPT switchover
When a multicast router detects that 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.

7.1.3 Preparations before Configuring PIM-SM

I. 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 calculate the
RPs corresponding to multicast groups according to the same algorithm after receiving
the C-RP messages that the BSR advertises.
It should be noted that one RP can serve multiple multicast groups or all multicast
groups. Each multicast group can only be uniquely correspondent to one RP at a time
rather than multiple RPs.
RPT
join
Multicast source registration
Huawei Technologies Proprietary
Chapter 7 PIM-SM Configuration
RP
7-2
Receiver