127
An RP can be manually configured or dynamically elected through the BSR mechanism. For a
large-scaled PIM network, configuring static RPs is a tedious job. Generally, static RPs are backups
for dynamic RPs to enhance the robustness and operational manageability on a multicast network.
Configuring a static RP
If only one dynamic RP exists on a network, you can configure a static RP to avoid communication
interruption caused by single-point failures. The static RP also avoids bandwidth waste due to
frequent message exchange between C-RPs and the BSR. The static RP configuration must be the
same on all routers in the BIDIR-PIM domain.
In BIDIR-PIM, a static RP can be specified with an unassigned IP address. This address must be on
the same subnet with the link on which the static RP is configured. For example, if the IP addresses
of the interfaces at the two ends of a link are 10.1.1.1/24 and 10.1.1.2/24, you can assign
10.1.1.100/24 to the static RP. As a result, the link becomes an RPL.
When you configure static RPs for BIDIR-PIM, follow these restrictions and guidelines:
•
You can configure the same static RP for different multicast groups by using the same RP
address but different ACLs.
•
You do not need to enable PIM for an interface to be configured as a static RP.
•
If you configure multiple static RPs for a multicast group, only the static RP with the highest IP
address takes effect.
To configure a static RP:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter PIM view.
pim
[
vpn-instance
vpn-instance-name
]
N/A
3.
Configure a static RP for
BIDIR-PIM.
static-rp
rp-address
bidir
[
ipv4-acl-number
|
preferred
] *
By default, no static RPs exist.
Configuring a C-RP
IMPORTANT:
When you configure a C-RP, reserve a large bandwidth between the C-RP and other devices in the
BIDIR-PIM domain.
In a BIDIR-PIM domain, if you want a router to become the RP, you can configure the router as a
C-RP. The BSR collects the C-RP information according to the received advertisement messages
from C-RPs or the auto-RP announcements from other routers. Then, it organizes the C-RP
information into the RP-set information, which is flooded throughout the entire network. Then, the
other routers on the network can determine the RPs for different multicast group ranges based on
the RP-set information. As a best practice, configure C-RPs on backbone routers.
To enable the BSR to distribute the RP-set information in the BIDIR-PIM domain, the C-RPs must
periodically send advertisement messages to the BSR. The BSR learns the C-RP information,
encapsulates the C-RP information and its own IP address in a BSM, and floods the BSM to all PIM
routers in the domain.
An advertisement message contains a holdtime option, which defines the C-RP lifetime for the
advertising C-RP. After the BSR receives an advertisement message from a C-RP, it starts a timer for
the C-RP. If the BSR does not receive any advertisement message when the timer expires, it
considers the C-RP failed or unreachable.
To configure a C-RP:
