The egress QoS marking for subscriber host traffic is derived from the SAP egress QoS policy associated with a corresponding SAP, instead of from the SLA profile associated with the corresponding subscriber host. Therefore, no egress QoS marking (Dot1p marking is set to 0, the dscp/prec field is kept unchanged) is performed for traffic transmitted on a managed SAP because by default, sap-egress policy 1 is attached to every managed SAP.
The default value of the ‟qos-marking-from-sap” flag is enabled. This means that the qos-marking defined in the SAP egress QoS policy associated with the SAP is used. The default setting of this flag in a combination with managed-SAP results in the same behavior as in the current system (dot1p=0, dscp/prec is unchanged).
If the no qos-marking-from-sap command is executed, then both the Dot1p marking and DSCP marking are derived from the sla-profile.
Changing the flag setting in the SLA profile being used by any subscriber-hosts (this includes subscriber-hosts on managed-SAPs as well) is allowed.
The following MC traffic characteristics apply:
On Layer 3 subscriber interfaces, MC is not supported so it is impossible to enable it at the SAP level or at the sla-instance level.
On Layer 2 SAPs, IGMP snooping is supported while it is not supported on the SLA instance level. Therefore, any MC traffic transmitted at egress belongs to a SAP (meaning it uses SAP queues), instead of to an SLA instance.
The special case are SAPs with a profiled-traffic-only flag enabled. Although it is possible to define an sla-profile applicable to a Layer 2 host, this is not taken as reference for marking mc-traffic, but rather SAP settings are used.