[c-nsp] Egress QoS on FE links with less than 100Mbps speeds

[Brad Henshaw]

Marian Ďurkovič wrote: 

> Flowcontrol doesn't need to be QOS-aware in this scenario.
> On the switch side, it's enough if it supports plain RX flowcontrol
> i.e. "flowcontrol receive [desired|on]". Then the wireless link can
> send pause frames to slow down the switch port automatically to the
> real bandwidth and output buffering / QOS configuration on the switch
> port is applied as expected.

That is assuming that the switch honours QoS and continues to prioritise packets appropriately when it receives a PAUSE from the radio gear - more often than not this is not the case and all traffic in the egress buffers will be equally affected.

I recall reading (maybe on this list) that the Nexium 5k or 7k supports QoS-aware flow control - but I wouldn't bet on it being included in low-end switches any time soon. (not that I'd complain if it was)

Regards,
Brad