Wireless Access


Lync CoS wrong?

Hi, recently did an audit concerning Lync implementation at a customer and running into an 'issue' I cannot realy explain.


In a packet capture at client level (on the client pc) of a client to client Lync call  I can see DSCP 46 being used for traffic in both directions. When I do a snif of the wlan traffic however I can see CoS priority 5 going one way (wlan client -> AP) with CoS priority 6 coming back (AP -> wlan client).


I only noticed this afterwards so did not test this further yet but since both clients are configured to use dscp 46 I don't see where this priority 5 comes from. Shouldn't the controller see its voice traffic and set CoS 6 automatically? 


We use ArubaOS 6.2 with a lync classify media policy to 'find' the voice traffic. DSCP mapping for WMM voice AC is set to 46.

Anyone got any insights to share in this?


edit: Ok, silly me.. dscp 46 = cos 5, not 6

WMM however says voice = cos 6


That explains the difference for traffic going up to the wlan or coming back from it.

Now, unfortunatally everything 'wired' says voice traffic should be classified expedited forwarding (CoS 5 aka dscp 46).


So then the question is, what sets the QoS values on client? Is it the application or the wireless driver? 

So who do I blame for this mismatch and what is the proper sollution? Go dscp48 ~ CoS 6 everywhere wired and wireless?


Koen (ACMX #351 | ACDX #547 | ACCP)

-- Found something helpful, important, or cool? Click the Kudos Star in a post.
-- Problem Solved? Click "Accept as Solution" in a post.
Search Airheads
Showing results for 
Search instead for 
Did you mean: