HP 3500YL - Manual (Page 121)

PIM-SM (Sparse Mode)
PIM-SM Operation and Router Types
Configuring a C-RP to support a given multicast group does not ensure
election of the C-RP to support that group unless the group is excluded from
all other RPs in the domain. Refer to “Redundant Group Coverage Provides
Fault-Tolerance” on page 4-17.
Also, within a PIM-SM domain, a router can be configured as a C-RP available
for a given multicast group or range of groups and as the static RP for a given
multicast group or range of groups. The recommended practice is to use C-
RPs for all multicast groups unless there is a need to ensure that a specific
group or range of groups is always supported by the same routing switch. For
more on this topic, refer to “Static Rendezvous Point (Static-RP)” on page 4-17.
Redundant Group Coverage Provides Fault-Tolerance. If a C-RP
elected to support a particular multicast group or range of groups becomes
unavailable, the router will be excluded from the RP-set. If the multicast group
configuration of one or more other C-RPs overlaps the configuration in the
failed RP, then another C-RP will be elected to support the multicast group(s)
formerly relying on the failed RP.
Static Rendezvous Point (Static-RP)
General Application. Like C-RPs, static-RPs control multicast forwarding
of specific multicast groups or ranges of contiguous groups. However, static-
RPs are not dynamically learned, and increase the configuration and monitor­
ing effort needed to maintain them. As a result static-RPs are not generally
recommended for use except where one of the following conditions applies:
■ It is desirable to designate a specific router interface as a backup RP for
specific group(s).
■ Specific multicast groups are expected, and a static-RP would help to
avoid overloading a given RP with a high volume of multicast traffic.
■ A C-RP for the same group(s) is less reliable than another RP that would
not normally be elected to support the group(s).
■ tighter traffic control or a higher priority is desired for specific multicast
groups
N o t e s While use of C-RPs and a BSR enable a dynamic selection of RPs for the
multicast group traffic in a network, using static-RPs involves manually
configuring all routers in the domain to be aware of each static RP. This can
increase the possibility of multicast traffic failure due to misconfigurations
within the PIM-SM domain. Also, because a BSR does not administer static-
RPs, troubleshooting PIM-SM traffic problems can become more complex.
4-17