Last mile packet size adjustment

In the application where pseudowire SAPs are used to apply access QoS for services aggregated from an Ethernet access network, MPLS labels may not be present on the last-mile and link from an access node. In these cases, policers, queues and H-QoS schedulers should account for packets without MPLS overhead, modeled as ‟encaps-offset”. Vport and port schedulers behave as per the table below. In the data-path, the actual pseudowire encap overhead (taking into account the MPLS labels) added to the packet is tracked, and may be applied to the scheduler calculations via the configured packet-byte-offset.

The rate limit configured for the pseudowire SAP accounts for subscriber or service frame wire rate: without MPLS overhead and including the last mile overhead (unless a packet-byte-offset is configured).

Table: Packet sizes used for pseudowire SAPs summarizes the default packet sizes used at each of the schedulers on the IOM/Ethernet MDA, assuming a 1000byte customer packet.