When all policers and queues for a SAP, multiservice site or subscriber or multiservice site instance are attached directly to the port scheduler (using the port-parent command), it is possible to configure an agg-rate limit for the queues. This is beneficial because the port scheduler does not provide a mechanism to enforce an aggregate SLA for a service or subscriber or multiservice site and the agg-rate limit provides this ability. Queues and policers may be provisioned directly on the port scheduler when it is desirable to manage the congestion at the egress port-based on class priority instead of on a per service object basis.
The agg-rate limit is not supported when one or more policers or queues on the object are attached to an intermediate service scheduler. In this event, it is expected that the intermediate scheduler hierarchy is used to enforce the aggregate SLA. Attaching an agg-rate limit is mutually exclusive to attaching an egress scheduler policy at the SAP or subscriber or multiservice site profile level. When an aggregate rate limit is in effect, a scheduler policy cannot be assigned. When a scheduler policy is assigned on the egress side of a SAP or subscriber or multiservice site profile, an agg-rate limit cannot be assigned.
Because the sap-egress policy defines a policer or queue parent association before the policy is associated with a service SAP or subscriber or multiservice site profile, it is possible for the policy to either not define a port-parent association or define an intermediate scheduler parenting that does not exist. Policers and queues in this state are considered to be orphaned and automatically attached to port scheduler priority 1. Orphaned policers and queues are included in the aggregate rate limiting behavior on the SAP or subscriber or multiservice site instance they are created within.