The c-bsr command configures a C-BSR.
The undo c-bsr command restores the default configuration.
By default, the C-BSR is not configured.
| Parameter | Description | Value |
|---|---|---|
| ipv6-address | Specifies the global IPv6 unicast address of a C-BSR. NOTE:
To avoid frequent protocol changes caused by interface flapping, use the loopback interface address as the global IPv6 unicast address of the C-BSR. |
The address is a 32-digit hexadecimal number, in the format X:X:X:X:X:X:X:X. |
| hash-length | Specifies the hash mask length of the C-BSR. The mask is used in a hash function to calculate the RP. | The value is an integer that ranges from 0 to 128. By default, the value is 126. |
| priority | Specifies a priority of the C-BSR. A larger value indicates a higher priority. | The value is an integer ranging from 0 to 255. By default, the value is 0. |
Usage Scenario
One or more C-BSRs need to be configured in a PIM-SM domain. A BSR is elected from multiple C-BSRs and is responsible for collecting C-RP information and summarizing C-RP information into an RP-set. The RP-set is then encapsulated in a BootStrap message and advertised to all the devices in the PIM domain.
The process of BSR election is as follows:
Each C-BSR considers itself as the BSR of the local PIM-SM domain and uses the IPv6 address of this interface as the address of the BSR to send Bootstrap messages.
When a C-BSR receives a Bootstrap message from other devices, it compares the BSR in the received Bootstrap message with the current BSR. The BSR with the highest priority is preferred. If BSRs have the same priority, the BSR with a larger IPv6 address is preferred. If the BSR carried in the received Bootstrap message is superior to the current BSR, the C-BSR replaces its BSR address with the BSR address carried in the received Bootstrap message.
Prerequisites
IPv6 multicast routing has been enabled using the multicast ipv6 routing-enable command in the system view.
Precautions
If PIM-SM (IPv6) is disabled on an interface, the interface can be configured as a C-BSR but the configuration does not take effect.
For the multicast BSR messages learned through the GRE tunnel, you need to configure a static multicast route to ensure that the next hop to the BSR is a GRE interface. You need to configure static multicast routes properly to avoid routing loops.