QoS and multilayer service support. A Supervisor Engine I provides only a single receive with two transmit queues. The Supervisor Engine IA, in contrast, provides two receive and three transmit queues. One queue for both received and transmitted traffic is reserved for strict, high-priority traffic, while the remaining queue(s) each support four Weighted Random Early Detection (WRED) drop thresholds for congestion avoidance.
Furthermore, the Supervisor Engine IA supports Weighted Round Robin (WRR) queue scheduling between the two flexible transmit queues that
support WRED, for fair bandwidth allocation between each queue.
It also supports the policy feature card (PFC) and the multilayer switch feature card (MSFC).
From a layer 2 standpoint, both the sup1 and sup1a will have the same performance.
