Configuration
See
Statically configuring an RP to accept multicast traffic
Operating rules and recommendations
Guideline for configuring C-RPs and BSRs
Routers in a PIM-SM domain should usually be configured as both C-RPs and candidate BSRs; this can
reduce some overhead traffic.
The SPT policy should be the same for all RPs in a domain.
Allowing some RPs to remain configured to implement SPTs while configuring other RPs in the same domain
to force RPT use can result in unstable traffic flows. (Use the
[no] ip pim-sparse spt-threshold
command to change between SPT and RPT operation on each router.)
Application of RPs to multicast groups.
In a PIM-SM domain, a given multicast group or range of groups can be supported by only one RP. (Typically,
multiple C-RPs in a domain are configured with overlapping coverage of multicast groups, but only one such
candidate will be elected to support a given group.)
Ensuring that the C-RPs in a PIM-SM domain cover all desired multicast groups.
All of the multicast groups you want to allow in a given PIM-SM domain must be included in the aggregate of
the multicast groups configured in the domain's C-RPs. In most cases, all C-RPs in a domain should be
configured to support all RP groups (the default configuration for a router enabled as a C-RP.) This provides
redundancy in case an RP becomes unavailable. (If the C-RP supporting a particular multicast group
becomes unavailable, another C-RP is elected to support the group as long as there is redundancy in the C-
RP configuration for multiple routers.) Note that is cases where routers are statically configured to support a
specific group or range of groups, the C-RP prioritization mechanism allows for redundant support.
PIM-SM and PIM-DM.
These two features cannot both be enabled on the same router at the same time.
Supporting PIM-SM across a PIM Domain.
To properly move multicast traffic across a PIM-SM domain, all routers in the domain must be configured to
support PIM-SM. That is, a router without PIM-SM capability blocks routed multicast traffic in a PIM-SM
domain.
Configuration steps for PIM-SM
This process assumes that the necessary VLANs and IP addressing have already been configured on the routing
switch.
NOTE:
The switches described in this guide do not support PMBR operation in the current software release.
Planning considerations
• Where multiple routers are available to operate as the DR for a given source, set the DR priority on each
router according to how you want the router used.
• Determine whether there are any bandwidth considerations that would call for disabling SPT operation. (If any
routers in the domain have SPT operation disabled, it should be disabled on all RPs in the domain. See
Operating rules for static RPs
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