From: John Matijevic (matijevi@bellsouth.net)
Date: Fri Aug 08 2003 - 10:31:46 GMT-3
Hello Nir,
You dont always have to have mls qos trust cos when configuring voice vlans.
If your going to change the cos value to 1 then yes you would use the
commnad switchport priority extend cos 1. And you would not want to use the
mls qos trust cos on the switchport becuase then you would be trusting the
cos value from the phone for tagged frames and would be using the default
value for untagged frames. In essence you want to use the mls qos trust cos,
when you would not want to modify the cos value.
Here is the documentation:
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12114ea1/3550scg/swvoip.htm
Sincerely,
Matijevic
----- Original Message -----
From: "Nir Wittenberg" <nwittenb@msncomm.com>
To: <ccielab@groupstudy.com>
Cc: <pborghese@groupstudy.com>
Sent: Friday, August 08, 2003 12:16 AM
Subject: mls qos trust cos
> Should we always use the "mls qos trust cos" when configuring a voice vlan
on the 3550?
>
> Say I want to have all data frame's COS value changed to 1 coming into an
IP phone access port. I would use the "switchport priority extend cos 1".
What if I didn't have the "mls qos trust cos" on the switchport? Would the
switch now use the default for the port and change the COS back to 0?
>
> Nir
>
>
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