A question about Cisco MLS and MQC QoS.
I read two things on a Cisco guide: https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/118629-technote-qos-00.html
On the 3750, by default the QoS is disabled whereas on the 3850, it is enabled. Also in order to preserve Layer 2 (L2)/Layer 3 (L3) QoS marking on the 3750 platform, a trust configuration must be applied.
In the case of the 3850, all packets by default are trusted (the L2/L3 QoS marking is preserved), unless you change it with an application of a specific policy map on the ingress or egress interface.
And, to perform a trust cos in a MQC model in Ingress:
Ingress: apply policy-map trust-cos Ingress policy:
3850#show run policy-map trust-cos class class-default set cos cos table default 3850#show table-map default Table Map default default copy
So the question, the guide explain that the trust cos/dscp is enabled by default on the MQC QoS model, but the guide explain how to apply a trust cos/dscp in ingress interface in MQC, so, what's true ?