3750X : use of the cos-output-q map

[elretnaya]

Hello,

I don't understand under which conditions the cos-output-q map is used.

As an internal DSCP label is added to the packets following classification (for non IP packets, the

cos-dscp map would be used to assign a DSCP label, as documented in the attached diagram from the 3750X Cisco documentation),

all queuing should be done with this internal DSCP label.

So when is the cos-output-q used (the same question applies to the cos-input-q map)?

Thank you!

Arnaud

[nkarpysh]

The things is that you want to prefer to trust COS within your switch wich is basically default. That's why you would need input and output cos queue maps. If you start trusitng DSCP then that is prefered over COS.

Nik