Videostream questions

[Thibault BRISSE]

Hello,

I diffuse in my network multicast video from wired to wireless with videostream feature enable. I am surprised to see that multicast are converted to unicast frame and marked with COS 4 only if I configured a media stream (wireless => media stream => stream). Please could you confirm me that is the normal operation ?

I also tried to diffuse multicast video from wireless to wireless/wired with videostream feature enable and with a media stream configured. Multicast frame are not converted to unicast and not marked with COS 4. Is this normal ?

Thanks a lot.

Regards,

Thibault

[Rasika Nayanajith · Accepted solution]

This should help you to understand the "video stream" feature & how it works. This is for wired -> Wireless multicast distribution.

http://mrncciew.com/2012/12/24/understanding-videostream-feature/

HTH

Rasika

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[Thibault BRISSE]

Hello Rasika,

I used your website to configure video stream feature. Thanks a lot to share your knowledges and experiences, it's very helpful.

If I understand correctly it's mandatory to add a multicast stream to convert the multicast frame to unicast frame. It's mandatory too to send the multicast frame (unicast) with UP 4. Am I right ?

Video stream feature works only from wired to wireless multicast. Do you know why this feature doesn't work from wireless to wired network ?

Regards,

Thibault

[Rasika Nayanajith · Accepted solution]

it's mandatory to add a multicast stream to convert the multicast frame to unicast frame.

Yes,you are right,without Video Stream feature AP won't convert a multicast frame to Unicast at the AP. If it is transmit to client as a multicast frame, then it is not reliable (no re-transmission, send at highest mandatory rate configured - not 802.11n rates)

It's mandatory too to send the multicast frame (unicast) with UP 4.

This is not configurable, as long as you configured WLAN for platinum profile (ie allow upto UP value of 6 frames within the BSS) AP will automattically mark video unicast traffic to UP of 4 (AC_VI or Video classification). So these frames will get priority over other BE or BK (Best Effort or Backgroud ) traffic.

Video stream feature works only from wired to wireless multicast. Do you know why this feature doesn't work from wireless to wired network ?

When it comes to wireless upstream, it is very difficult to AP to control that traffic. It is purely upto wireless client to decide how wireless end device mark that traffic. Once traffic hits the AP then again traffic will be CAPWAP back to WLC & your wired network cannot see internal video traffic to give high priority within your wired network. So it is little bit different in this direction.

In downstream since AP is the last hop before the client, it can do the conversions, markup easily

Hope that make sense. 

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Rasika

[Thibault BRISSE]

Yes that make sense, thanks. Just one more question. From your multicast post capwap header is marked with dscp af41. I saw in the enterprise mobility 7.3 design guide that multicast traffic is sent from wlc to ap as best effort only (hard coded and not user changeable). It is wrong ?

i am sorry but I can't make test currently. 

Thibault 

[Rasika Nayanajith]

Hi 

Yes, I saw below in the 7.3 mobility guide

When the controller receives a multicast packet from any of the client VLANs on the first hop router, it transmits the packet to the CAPWAP multicast group via the management interface at the best effort QoS classification. The QoS bits for the CAPWAP multicast packet are hard coded at the lowest level and are not user changeable.

But as you saw in my packet capture, it showed a different thing. My capture is based on 7.0.116.0 code & I assume packet never lies :)

If I get time, I will do a similar test with latest controller code & let you know

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HTH

Rasika

[Thibault BRISSE]

Hi,

You are right packet capture never lies. Thanks a lot.

Thibault