The bootstrap mechanism in a PIM router, is a non-proprietary technology providing a fault tolerant, automated rendezvous point discovery and distribution mechanism. The non-proprietary technology is described in RFC 5059
PIM uses the bootstrap router mechanism to discover and announce rendezvous point information for each group prefix to all routers within a PIM domain.
The object that PIM Bootstrap router accomplishes is that same as the Cisco proprietary ‘Auto-RP’. Bootstrap router mechanism is part of the PIM Version 2 specification.
The rendezvous point information announcements contain the following information:
- Multicast group range
- Rendezvous point address
- Rendezvous point priority
- Hash mask length
- SM/Bidir Flag
Bootstrap router messages originate on the bootstrap router, and are flooded to each hop by intermediate routers.
When a bootstrap message is received on an intermediate router, it is forwarded out of every PIM-enabled interface on that router that has a PIM neighbour, including the interface where the message was received.
Bootstrap messages are sent to the multicast address of 188.8.131.52 with a time to live of 1.
To avoid a single point of failure with a single bootstrap router, multiple candidate bootstrap routers can be deployed through a PIM domain. All candidate bootstrap routers will participate in a bootstrap router process by sending PIM bootstrap router messages containing their priority out of all PIM enabled interfaces.