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The C-RPs periodically send advertisement messages to the BSR, which collects RP set information for the
RP election. You can configure the interval for sending the advertisement messages.
The holdtime option in C-RP advertisement messages defines the C-RP lifetime for the advertising C-RP.
The BSR starts a holdtime timer for a C-RP after it receives an advertisement message from a C-RP. If the
BSR does not receive any advertisement message when the timer expires, it considers the C-RP failed or
unreachable.
To guard against C-RP spoofing, configure a filtering policy on the BSR to define the legal C-RP address
range and the multicast group range to which the C-RP is designated. In addition, because every C-BSR
might become the BSR, you must configure the same filtering policy on all C-BSRs in the IPv6 PIM-SM
domain.
When you configure a C-RP, reserve a relatively large bandwidth between the C-RP and the other devices
in the IPv6 PIM-SM domain.
To configure a C-RP:
Ste
Command
Remarks
1. Enter system view.
system-view
N/A
2. Enter IPv6 PIM view.
ipv6 pim [ vpn-instance
vpn-instance-name ]
N/A
3. Configure a C-RP.
c-rp ipv6-address [ advertisement-interval
adv-interval | { group-policy acl6-number
| scope scope-id } | holdtime hold-time |
priority priority ] *
By default, no C-RP is
configured.
4. (Optional.) Configure a legal
C-RP address range and the
IPv6 multicast group range to
which the C-RP is designated.
crp-policy acl6-number
By default, no restrictions
are defined.
Configuring a BSR
You must configure a BSR if C-RPs are configured to dynamically select the RP. In a network with a static
RP, this configuration task is unnecessary.
An IPv6 PIM-SM domain can have only one BSR, but must have at least one C-BSR. Any router can be
configured as a C-BSR. Elected from C-BSRs, the BSR is responsible for collecting and advertising RP
information in the IPv6 PIM-SM domain.
Configuring a C-BSR
C-BSRs should be configured on routers on the backbone network. The BSR election process is
summarized as follows:
1. Initially, each C-BSR regards itself as the BSR of the IPv6 PIM-SM domain and sends BSMs to other
routers in the domain.
2. When a C-BSR receives the BSM from another C-BSR, it compares its own priority with the priority
carried in the message. The C-BSR with a higher priority wins the BSR election. If a tie exists in the
priority, the C-BSR with a higher IPv6 address wins. The loser uses the winner's BSR address to
replace its own BSR address and no longer regards itself as the BSR. The winner retains its own
BSR address and continues to regard itself as the BSR.
In an IPv6 PIM-SM domain, the BSR does the following:
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