Juniper JUNOSE 11.1.X MULTICAST ROUTING, Configuration Manual

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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. Two bootstrap mechanisms
exist—bootstrap router (BSR) or auto-RP. Auto-RP is not used in IPv6 implementations.
When implemented, BSR operates as follows:
1.
One router in each PIM domain is elected the BSR.
2.
All the routers in the domain that are configured to be RP candidates periodically
unicast their candidacy to the BSR.
3.
The BSR picks an RP set from the available candidates and periodically announces
this set in a bootstrap message.
4.
Bootstrap messages are flooded hop by hop throughout the domain until all
routers in the domain learn the RP Set.
PIM Source-Specific Multicast
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.
Overview
■ 217
Chapter 7: Configuring PIM for IPv6 Multicast