QoS: make switch to trust PC's DSCP marking

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May 18th, 2009
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As you all know, it's possible to override 802.1p/CoS field coming from PC attached to Catalyst switch.

This is accomplished in 2 (two) ways:

- either by '(config-if)# mls qos trust extend cos <value>'

- or via '(config-if)# switchport priority extend cos <value>'

But what about to make Cisco IP Phone to trust PC's DSCP marking ? Is this possible ?


Can you also explain, why there 2 (two) flavors of CLI to allow switch to trust to PC's 802.1p marking ?


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Tobivan_Helden_2 Mon, 05/18/2009 - 00:30
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Sorry for mistyping.

I mean, the PC of course attached to Cisco IP PHone which in turn attached to Cisco Catalyst switch.

a.cruea1980 Fri, 05/29/2009 - 11:57
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Tobi -

I believe there are two versions of the command for the 2 types of switches: pure layer 2 switches, and multi-layer switches.

2900 series being a pure layer 2 switch, 4500/6500 being a multi-layer switch.


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