Edge-Core AS5700-54X, Справочное руководство CLI, Страница: 1063 / 1116

Chapter 30
| Multicast Routing Commands
PIM Multicast Routing
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seconds - The interval at which this device advertises itself as an RP
candidate. (Range: 60-16383 seconds)
value - Priority used by the candidate RP in the election process. The RP
candidate with the largest priority is preferred. If the priority values are the
same, the candidate with the larger IP address is elected to be the RP.
Setting the priority to zero means that this router is not eligible to server as
the RP. (Range: 0-255)
Default Setting
Interval: 60 seconds
Priority: 0
Command Mode
Global Configuration
Command Usage
◆
When the ipv6 pim rp-candidate command is entered, the router 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 el6ection 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 a 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.