Defining supported multicast groups

An RP in the default candidate configuration supports the entire range of possible multicast groups. This range is expressed as a multicast address and mask, where the mask defines whether the address is for a single address or a range of contiguous addresses:

Multicast address


Address range -

An alternate way to express the above (default) address and mask is:

In non-default candidate configurations, an RP allows up to four ranges of contiguous multicast groups, and/or individual multicast groups, or both. For example:

RP candidate configuration

Supported range of multicast groups — — only only


If a given multicast group is excluded from all RPs in a given domain, then that group will not be available to the multicast receivers connected in the domain.

For more on this topic, see Configuring C-RPs on PIM-SM routers.