Trust Question: mls qos trust Vs. mls qos trust device

Based on the three configurations below, are my conclusions correct?

 Any feedback would be appreciated.

Thanks.

Configuration #2,

  The port will trust COS unconditionally

Configuration #3,

  The port will trust COS *only if* there is a CISCO phone attached

Configuration #1,

  The port will not trust under any condition, because the it also requires
a mls qos trust Command.

*> Config 1<*

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Rack29SW2#show run int fa0/8

Building configuration...

Current configuration : 176 bytes

!

interface FastEthernet0/8

 switchport access vlan 5

 switchport voice vlan 4

 switchport priority extend cos 1

 mls qos trust device cisco-phone < - - - -

 spanning-tree portfast

end

Rack29SW2#show mls qos inter fa0/8

FastEthernet0/8

trust state: not trusted < - - - -

trust mode: not trusted < - - - -

trust enabled flag: dis

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

Trust device: cisco-phone

qos mode: port-based

Rack29SW2#

*> Config 2<*

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Rack29SW2#show run int fa0/8

Apr 14 11:49:07.358: %SYS-5-CONFIG_I: Configured from console by console

Building configuration...

Current configuration : 161 bytes

!

interface FastEthernet0/8

 switchport access vlan 5

 switchport voice vlan 4

 switchport priority extend cos 1

 mls qos trust cos < - - - -

 spanning-tree portfast

end

Rack29SW2#

Rack29SW2#show mls qos inter fa0/8

FastEthernet0/8

trust state: trust cos < - - - -

trust mode: trust cos < - - - -

trust enabled flag: ena

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

Trust device: none

qos mode: port-based

*> Config 3<*

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

!

interface FastEthernet0/8

 switchport access vlan 5

 switchport voice vlan 4

 switchport priority extend cos 1

 mls qos trust device cisco-phone < - - - -

 mls qos trust cos < - - - -

 spanning-tree portfast

end

Rack29SW2#

Rack29SW2#

Rack29SW2#show mls qos inter fa0/8

FastEthernet0/8

trust state: not trusted < - - - -

trust mode: trust cos < - - - -

trust enabled flag: dis

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

Trust device: cisco-phone

qos mode: port-based

Blogs and organic groups at http://www.ccie.net
Received on Sun Apr 14 2013 - 12:03:19 ART