(Optional) Adjusting C-BSR Control Parameters

Candidate bootstrap routers (C-BSRs) automatically elect a BSR in an IPv6 PIM domain. At first, each C-BSR considers itself as a BSR and sends Bootstrap messages to all devices in the domain. When a C-BSR receives a Bootstrap message from another C-BSR, it compares the priority in the received Bootstrap message with its own priority. The C-BSR with a higher priority wins. If the two BSRs have the same priority, the BSR with a larger IP address is preferred. After a C-BSR is elected as the BSR, it encapsulates its own IP address and the RP-Set information into a Bootstrap message and sends the Bootstrap message in the PIM domain. The losers stop sending Bootstrap messages. The Bootstrap message contains a hash mask which is used for hash calculation in rendezvous point (RP) election.

The BSR periodically sends a Bootstrap message to the network. When the other C-BSRs receive the Bootstrap message, they start the holdtime timer. If they do not receive any Bootstrap message from the BSR when the holdtime timer expires, they consider that the BSR fails and initiate the election of a new BSR. The interval for sending Bootstrap messages must be smaller than the holdtime of a Bootstrap message.

You can configure the C-BSR priority, the BSR hash mask length, the interval for sending Bootstrap messages, and the holdtime of Bootstrap messages. To prevent BSR spoofing, set a range of valid BSR addresses on devices, so that the devices receive messages only from the BSRs within the address range.

Default Settings

Table 1 lists the default settings of the C-BSR.

For the default values of other C-BSR parameters, see Configuring an RP.