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Community Member

AVC question (MS-LYNC-MEDIA)

Good Morning,

I am having trouble tracking down some useful information.

Currently I am working through testing using AVC to mark\drop packets on our standard DATA WLAN. I would like this to work so i can put my best foot forward with marking our LYNC softclient voice calls as EF 46 and traverse our network end-to-end with priority.

So... here is what i have run into.

I put a Lync for Mac 2011 and Windows Lync 2013\2010 on the same WLAN and set to Drop MS-LYNC-MEDIA. So.. a call orginating from the Lync for Mac 2011 client works with 2 way audio. The Windows client however sets up teh call but no audio.

I would like to know what exactly MS-LYNC-MEDIA entails to rule out if its a client issue, lync environment issue or other. I cannot find out what the AVC applications truly mean, is it DSCP value with other packet headers? What does it scan on to classify it as the Application set?

Anyone know where I can find such infromation for all AVC defined applications.

12 REPLIES
VIP Purple

Re: AVC question (MS-LYNC-MEDIA)

Hi,

AVC uses NBAR2 application signatures to classify the traffic. Here is the full protocol list supported in NBAR2

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6558/ps6616/product_bulletin_c25-627831.html

Try to select both "ms-lync" & "ms-lync-media" & see

With AVC, you need to remember it will re-classify at WLC level. This mean from wirless client upto WLC it won't help in upstream direction (beyond WLC it will). For downstream, it will work from WLC upto wireless client.

HTH

Rasika

**** Pls rate all useful responeses ****

Community Member

AVC question (MS-LYNC-MEDIA)

This is good information. It appears that the Lync for Mac client is just not marking or packetizing the traffic appropriatley.

I checked an upstream communication and the Lync for Mac client is not even marking the traffic for Cos 6 but rather as Best Effort.

I feel like this might be a losing battle for the MAC clients.

However traffic destined to the MAC client will be properly marked by AVC, but seems rather pointless if both streams are not classified correctly.

VIP Purple

AVC question (MS-LYNC-MEDIA)

Yes, lot of these client devices/applications does not correctly mark traffic as per WMM classification. I have done some testing with BYOD type of devices sometime back & below was my results.

http://mrncciew.com/2013/01/08/byod-with-qos/

Unless these applications/client drivers mark these correctly it is very little we can do from WLC or AVC perspective for upstream traffic

HTH

Rasika

**** Pls rate all useful responese *****

Bronze

AVC question (MS-LYNC-MEDIA)

Hi

Just to add, Windows 7 laptops can appropriately mark the Lync application if you set the UP value under the Group Policy Object. Under Computer config ( Policy Qos) add the communicator.exe application and specify the DSCP value.

Cheers

AVC question (MS-LYNC-MEDIA)

Here is another good link to reference

http://www.revolutionwifi.net/2011/09/microsoft-lync-qos.html

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"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
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"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
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Community Member

I am running WLC5508 on

I am running WLC5508 on version 7.4.110.0.  I am having a hard time understanding what practical purpose AVC serves in relation to Wireless Lync QoS.  As I understand it; I am forced to have my mobile application mark frames and subsequently trust these on my SSID by setting the SSID QoS setting to Platinum.  This means essentially any wireless application on this SSID can simply mark frames and reap the benifits?  I was hoping and under the impression that AVC could in some way prioritize a Lync identified stream directly on the CUWN access point (perhaps after an initial chit-chat with the WLC) without the need for client marking.  Perhaps reduce the CTS/RTS timers for frames specifically related to this stream or however its done.

In short:  Is there any way to prioritize upstream Wireless Lync WITHOUT the need for client frame marking?

Thank you :)

VIP Purple

In short:  Is there any way

In short:  Is there any way to prioritize upstream Wireless Lync WITHOUT the need for client frame marking?

Unfortunately answer is NO. AVC kick in at the WLC level for upstream traffic & you cannot change QoS marking of those frames prior to hit the WLC.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/AVC_dg7point5.html

The AVC/NBAR2 engine on the controller interoperates with the QoS settings on the specific WLAN. The NBAR2 functionality is based on the DSCP setting.

The following occurs to the packets in Upstream and Downstream directions if AVC and QoS are configured on the same WLAN:

Upstream

1. Packet comes with or without inner DSCP from wireless side (wireless client).

2. AP will add DSCP in the CAPWAP header that is configured on WLAN (QoS based configuration).

3. WLC will remove CAPWAP header.

4. AVC module on the controller will overwrite the DSCP to the configured marked value in the AVC profile and send it out.

Downstream

1. Packet comes from switch with or without inner DSCP wired side value.

2. AVC module will overwrite the inner DSCP value.

3. Controller will compare WLAN QoS configuration (as per 802.1p value that is actually 802.11e) with inner DSCP value that NBAR had overwritten. WLC will choose the lesser value and put it into CAPWAP header for DSCP.

4. WLC will send out the packet to AP with QoS WLAN setting on the outer CAPWAP and AVC inner DSCP setting.

5. AP strips the CAPWAP header and sends the packet on air with AVC DSCP setting; if AVC was not applied to an application then that application will adopt the QoS setting of the WLAN.

HTH

Rasika

**** Pls rate all useful responses ****

Community Member

Thank you your answer is very

Thank you your answer is very useful.  One final question; With regards to the upstream point 2. AP will add DSCP in the CAPWAP header that is configured on WLAN (QoS based configuration)

Does this impose any priority benefits at the layer 2 (MAC-Layer) with regards to e.g. initial contention window size?  I am simply wondering if there is any mechanism available that will truely prioritize my mobile lync application when contending for air time.

 

VIP Purple

You can optimize contention

You can optimize contention window for Voice or Voice+Video traffic under "Wireless -> 802.11b/g/n|802.11a/n -> EDCA Parameter" setting of your WLC.

This assumes your end device correctly classifying traffic onto Voice, Video, Best Effort & Backgroud queues in wireless frames (UP value of wireless header). So unless your client device does not do that you cannot prioritize voice frames over the other on upstream direction from client. I think MS-LYNC traffic does not classify correctly as Voice in UP value of wireless frame & hence cannot be prioratized. 

Here is the behavior of few client devices (with respect to Cisco Jabber) when I did testing sometime back. As you can see most of them send traffic as BE-Best Effort & in turn does not get any priority over others even those are voice packets.

http://mrncciew.com/2013/01/08/byod-with-qos/

 

HTH

Rasika

**** Pls rate all useful responses ****

Community Member

AVC question (MS-LYNC-MEDIA)

Thank you all for the information.

I have come to the realization that the issue I am running into strictly has to deal with the Lync for MAC client. I have yet to see what the Windows Client is doing for Lync 2010 and Lync 2013, but based on my readings the 2010 is most likely going to mark incorrectly and the 2013 has leveraged the wireless driver to handle most of this. We'll have to see when i get a chance to sniff the packets coming from the Windows 7 clients.

Thanks again all. Good write ups!

VIP Purple

AVC question (MS-LYNC-MEDIA)

Do not forget to rate our responses if that were helpful to you...

Rasika

Cisco Employee

Re: AVC question (MS-LYNC-MEDIA)

http://technet.microsoft.com/en-us/library/gg405413(v=ocs.14).aspx

Creating a Quality of Service (QoS) Policy on Lync Server

http://www.microsoft.com/en-us/download/dlx/thankyou.aspx?id=12633

Enabling Quality of Service with Microsoft Lync Server 2010

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