ECS4660-28F_Management Guide-R03

C HAPTER 21 | Multicast Routing
Configuring PIM for IPv4
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Figure 531: Showing PIM Static Rendezvous Points
CONFIGURING A
PIM RP CANDIDATE
Use the Routing Protocol > PIM > SM (RP Candidate) page to configure the
switch to advertise itself as a Rendezvous Point (RP) candidate to the
bootstrap router (BSR).
CLI REFERENCES
◆ "ip pim rp-candidate" on page 1942
COMMAND USAGE
◆ When this router is configured as an RP candidate, it periodically sends
PIMv2 messages to the BSR advertising itself as a candidate RP for the
specified group addresses. The IP address of the designated VLAN is
sent as the candidate’s RP address. The BSR places information about
all of the candidate RPs in subsequent bootstrap messages. The BSR
uses the RP-election hash algorithm to select an active RP for each
group range. The election process is performed by the BSR only for its
own use. Each PIM-SM router that receives the list of RP candidates
from the BSR also elects an active RP for each group range using the
same election process.
◆ The election process for each group is based on the following criteria:
■
Find all RPs with the most specific group range.
■
Select those with the highest priority (lowest priority value).
■
Compute hash value based on the group address, RP address,
priority, and hash mask included in the bootstrap messages.
■
If there is a tie, use the candidate RP with the highest IP address.
◆ This distributed election process provides faster convergence and
minimal disruption when an RP fails. It also serves to provide load
balancing by distributing groups across multiple RPs. Moreover, when
an RP fails, the responsible RPs are re-elected on each router, and the
groups automatically distributed to the remaining RPs.
◆ To improve failover recovery, it is advisable to select at least two core
routers in diverse locations, each to serve as both a candidate BSR and
candidate RP. It is also preferable to set up one of these routers as both
the primary BSR and RP.