Joining Groups; Timers; Pim Sparse Mode Bootstrap Router - Juniper JUNOSE 11.0.X MULTICAST ROUTING Configuration Manual

JUNOSe 11.0.x Multicast Routing Configuration Guide
When all designated routers associated with a specific RP router have switched to
the SPT, the RP router sends a join/prune message toward the multicast source.
When the multicast source receives this message, it stops sending multicast data
through the SPT.

Joining Groups

A host's designated router (DR) sends join messages to the RP when that host wants
to join a group. When a host wants to leave a group, it communicates with its
designated router through IGMP. When the designated router no longer has any hosts
that belong to a particular group, it sends a prune message to the RP.

Timers

PIM sparse mode uses timers to maintain the networking trees.
NOTE: PIM sparse mode routers poll their neighbors and hosts for various pieces of
information at set intervals.
If a PIM sparse mode router does not receive information from a neighbor or host
within a specific time, known as the hold time, it removes the associated information
from its routing tables.
You can configure how often an interface sends hello messages (hello interval) and
how often routers send RP announce messages (RP announce interval). The hold-time
associated with hello messages is 3.5 times the hello interval, and the holdtime
associated with RP announce messages is 2.5 times the RP announce interval.
All other timers are fixed and take the default values recommended in RFC
2934 Protocol Independent Multicast MIB for IPv4 (October 2000).

PIM Sparse Mode Bootstrap Router

PIM sparse mode routers need the address of the rendezvous point (RP) for each
group for which they have (*,G) state. They obtain this address either through a
bootstrap mechanism or through static configuration. PIM sparse mode routers
commonly use one of two bootstrap mechanisms: bootstrap router (BSR) or auto-RP.
Auto-RP is standards based, but is not used in IPv6 implementations, so BSR
configuration has become more popular.
When implemented, BSR operates as follows:
1.
2.
3.
4.
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Overview
One router in each PIM domain is elected the BSR.
All the routers in the domain that are configured to be RP candidates periodically
unicast their candidacy to the BSR.
The BSR picks an RP set from the available candidates and periodically announces
this set in a bootstrap message.
Bootstrap messages are flooded hop by hop throughout the domain until all
routers in the domain learn the RP set.