05-06-2021 05:07 PM
if we enable mls Qos command on a C3560, by default, all ports are untrusted + COS override:dis + default COS:0.
if we have the below, what will be the QoS value at the egress?
Untagged frame (Access port connect PC) - at egress will be COS:0???
Tagged frame (Trunk port 802.1Q w COS:5) - at egress will be COS:5 or 0???
05-07-2021 06:14 AM
I recall (?) for the 3560 (and 3750), the default, with mls QoS enabled, is untrusted ingress ports ToS and CoS are set to zero.
05-08-2021 02:13 AM
in that case, in what scenario is this parameter COS override:dis be used?
05-08-2021 07:37 AM
I don't recall. Not a feature I've ever used, especially I generally only use L3 ToS, not L2 CoS, as the former carries end-to-end, but the latter only useful with tagged frames, which often has a very limited life in the end-to-end path.
But if you have a link to Cisco's corresponding documentation, I might be able to "translate".
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