Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - MULTICAST ROUTING CONFIGURATION GUIDE 2010-10-07 Configuration Manual page 235

PIM Sparse Mode Bootstrap Router
PIM Source-Specific Multicast
Copyright © 2010, Juniper Networks, Inc.
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 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. Two bootstrap mechanisms exist—bootstrap
router (BSR) or auto-RP. Auto-RP is not used in IPv6 implementations.
When implemented, BSR operates as follows:
One router in each PIM domain is elected the BSR.
1.
All the routers in the domain that are configured to be RP candidates periodically
2.
unicast their candidacy to the BSR.
The BSR picks an RP set from the available candidates and periodically announces
3.
this set in a bootstrap message.
Bootstrap messages are flooded hop by hop throughout the domain until all routers
4.
in the domain learn the RP Set.
PIM source-specific multicast (SSM) is an extension of the PIM protocol. Using SSM, a
client can receive multicast traffic directly from the source. PIM SSM uses PIM sparse
mode functionality to create an SPT between the client and the source, but builds the
SPT without using an RP.
By default, the SSM group multicast address is limited to the IPv6 address range FF3x::/96
where x represents any valid scope. You can use the ipv6 pim ssm range command to
change the SSM group address range.
Advantages that an SSM-configured network has over a traditionally configured PIM
sparse mode network include the following:
Chapter 7: Configuring PIM for IPv6 Multicast
213