MCAC interface policies are defined system wide and used on MCAC interfaces via assignment of the policy to one or more interfaces to, for example, limit multicast BW across a group of interfaces/ports, across a line card or across a system. If an MCAC interface policy is assigned to an interface with Interface-level constraints configured, then both Interface-level MCAC as described above and MCAC-interface-policy-level MCAC must be satisfied for a channel to be admitted.
Mandatory and optional channels are allowed under the following conditions.
Mandatory channels—The bandwidth for the already-accepted mandatory channels on this and any other interface using this MCAC interface policy plus the bandwidth of this channel cannot be greater than the configured mandatory bandwidth for this MCAC interface policy.
Optional channels—The bandwidth for the already-accepted optional channels on this and any other interface using this MCAC interface policy plus the bandwidth of this channel cannot be greater than the configured amount of unconstrained bandwidth less the configured amount of mandatory bandwidth for this MCAC interface policy.
Thus, when MCAC interface policy is used, admitting a channel on one interface affects all interfaces sharing the same MCAC interface policy.