cos field in the frame

From: Braychuck Vitaliy (Vitaliy.Braychuck@incom.ua)
Date: Wed Feb 04 2009 - 14:15:05 ARST


Hi, gents.

Please, could you explain me how it should works and what I did not right.

I am trying to figure out the behavior of qos implementation on Cisco 3750
switch.

That's my topology:

 Fa0/0 gi1/0/2 gig1/0/23

[router2]------------------[switch2]--------------------[bsd-box]

 .2 173.1.0.0/24
.254

I have configured trunks between router2&switch2 and switch2&bsd-box.

I have configured on port gig1/0/2 "mls qos trust cos" and globally enabled
"mls qos".

From router2 I have been sending frames with cos 4 toward bsd-box and I got
frames with cos 0 and IP packets with 0x20 on it.

It's sounds like mls qos mapping works, but why I got frames with cos value
equal zero?

On bsd-box I am using wireshark as sniffer program.

Kindly,

Vitalii Braichuk

Blogs and organic groups at http://www.ccie.net



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