QoS - can u trust dscp and cos?

Hello,
is it possible to trust DSCP and COS at the same time?
If so, which one wins?

G'day,
It does not really make sense to trust both DSCP and CoS at the same time. You configure your switch to trust one or none of these.
As an example, if you did have the capability to trust both DSCP and CoS, imagine what would happen if you received a frame with DSCP EF and CoS 0 ? You would be faced with a conflicting situation ... if you trusted CoS, you would give a potentially high-priority packet lesser service. Whereas if you trusted DSCP, you could end up giving a potentially low-priority packet voice-like service... So the option of trusting both is not allowed.
Hope that helps - pls rate the post if it does.
Paresh

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