A、 on all ingress interfaces； to ensure maximum throughput on a per-egress， per-CoS basis

B、 on all ingress interfaces； to provide independent congestion management and 16 queues

C、 on all egress interfaces； so that a congested egress port does not affect traffic directed to other egress ports

D、 on all egress interfaces； to prevent head-of-line blocking by utilizing multiple virtual output queues

E、 on all egress interfaces； to be able to use EEE 802.1p CoS