QoS Cos question

[hanwucisco]

Show auto qos

Initial configuration applied by autoqos:

.....

mls qos map cos-dscp 0 8 16 26 32 46 48 56

!

interface FastEthernet0/10

mls qos trust device cisco-phone

mls qos trust cos

=====

Based on the show output, why are these two claims not right?

1.interface fa0/10 trusts all Cos vlues.

2.the trust boundary is not on this switch.

thanks,

Han

[Edison Ortiz · Accepted solution]

The command mls qos trust device cisco-phone will prevail, per the documentation:

http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_m2.html#wp1044294

Configures Cisco Discovery Protocol (CDP) to detect whether or not a Cisco IP phone is attached to the port.

•If CDP detects a Cisco IP phone, QoS applies a configured mls qos trust dscp, mls qos trust ip-precedence, or mls qos trust cos interface command.

•If CDP does not detect a Cisco IP phone, QoS ignores any configured nondefault trust state.