Need help for COS

MACattackMACattack Member Posts: 121
in CCNP
Hi just need some help. I am studying QOS right now, a user can set the cos and DSCP value of a packet. (this is clear)

Let say a user can set it's COS to high priority, but my switches doesn't have trunking connection let say typical normal connection (no trunking). Please correct me if I am wrong,
The switch which only know classification in COS not in DSCP, if it does not have configuredtrunking interface next to the neighbor switches. I cannot identify the COS, since cos can be found in the vlan tag.

Am I right?

For short if I don't set trunking at all does it mean the COS from the packet is ignored... not drop...
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  • EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
    Yes the Cos is transmitted within the vlan tag so if you dont have a trunk Cos wont be sent.Maybe you can translate the received dscp into a cos at the farend switch, thats if its a layer 3 switch of course.
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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  • MACattackMACattack Member Posts: 121
    Thank you very much ED, I ask this question to clear up as I enjoy reading and learning new stuff, new things comes in my brain... I think that is the effect of getting deeper and deeper in Cisco stuff.

    With the QOS I finally got that our network is congested using NBAR to classify, although I don;t have authority to modify configs in our network. Crazy "Net Admin: he thinks he knows too much...


    Like yesterday I spend 5 hours configuring and tesing the SDM though some func. I am not familiar.

    I want to try Voice but I have tested on uying CCM Express, no tools like CCM and unity.
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