QOS DSCP and WMM/802.11e

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Hi, we are running voice and video over ip. We mark voice and video using dscp values. Am I correct in thinking that I only need a qos classifier using only dscp to map to the aerohive classes. The client takes care of the wmm marking at layer 2 on client to AP side using the driver level dscp to wmm conversion. The outbound AP to the wifi client uses the dscp value and gets the wmm/802.11e marking again from the same classifier map. How is QOS on the eth0 handled or is it inherited from the aerohive classes ?
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Ben Moore

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Posted 4 years ago

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Andrew MacTaggart, Champ

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Note: The egress wireless interface is marked with 802.11e automatically.

you can be selective or

Note: By default, the chosen maps are applied to all interfaces and SSIDs.

if the AP is on a trunk and a layer 2 access switch you would use 802.11e/802.1p

Since there is no controller, traffic is terminated at the edge switch

So your edge switch would have to trust the markings from the AP and then when you reach a router you need to trust the layer 2 802.11e/802.1p and or map them to layer 3 dcsp values.

you can change markings along the way as well



Some good info here as well, but from the controller world, but the principles are simular





Some notes from my studies:

QoS on wireless is useless if it is not configured on the wired side.

Qos is not a fix for unreliable RF domain

QoS is probalistic on wireless -giving a higher statistical chance to access the medium

VoIP requires low throughput, low latency, low jitter and low loss

Classification starts at layer 7 of the client device

After the data is passed to the medium it must be classified [identified as traffic requiring QoS prioritization] and honored [scheduled or queued]

Incoming traffic is Classified

Outgoing traffic is marked

802.11e and WMM defines how QoS works within and Between 802.11 stations

the traffic will most likely have to travel over layer 2 and layer 3 devices [Switches and Routers]

Wireless frame must be translated to Ethernet frame and the QoS markings must translated to the new medium and honored 802.11p for Layer2 and DCSP for layer 3

classification can be applied on a per hop basis or via trusted markings in the frame or packet headers

Queuing and Scheduling defines how the classified data is handled and processed for outgoing transmission.


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Ben Moore

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Thanks, some really good resources there. I had stumbled across a couple of them before. It is a wifi QOS deployment for lync I am working on at the moment.

Any info/experience on the on the Aerohive queuing behaviour of the AP eth0 interface, I would like to assume if it follows the 8 class aerohive model and the customisable per user queue management( strict vs wrr ) queues also apply for the Eth interface ? The documentation I can find is minimal.

As I am not using a marker policy, the dscp value is maintained correctly for the wired lan as required in all instances.

Towards the client Voice is marked as DSCP 46 and the DSCP value is read by the classifier and marked wmm voice because of the DSCP to aerohive class relationship. It also gains its correct wmm voice marking as a result of automatic marking going onto the wireless medium.  " Note: The egress wireless interface is marked with 802.11e automatically. " Great exactly what we want.

Here is what I have setup currently as a test

My current problem

Towards the LAN from the Wifi client, voice traffic is marked in group policy to DSCP 46 and WMM Video class is also applied to the 802.11 frame by the wifi nic driver. The inbound frame has the 802.11e wmm marking of video and the l3 dscp value of 46. In this case which one wins so to speak,  in term of the classifier and the resulting queue ?

This could important in my case as the classifier map puts dscp value of 46 into the Aerohive Voice queue 6 and the 802.11e tag of Video would put it into Aerohive 5-video by default unless I change the default 802.11e to aerohive class mappings.


Does disabling 802.11e in the classfier map ignore or just use the defaults, same for dscp ?

From the manual
"The QoS classification tables in this section show the mapping of priority values of QoS classification systems on incoming packets to Aerohive classes. To enable the mapping of one of these classification systems to the Aerohive system, select 802.1p/DiffServ/802.11e, and then select the check box of one of the three systems. You can use the default mappings or modify them if necessary."

I feel a support ticket coming on...

On a side note - I may get the dscp changed to 48 which clears things up, but I'll see on that one.

Hopefully this thead might be useful to other people attempting to support QOS on Wireless.
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Andrew MacTaggart, Champ

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Have you tried adding microsoft lync as a service and select voice?

also found another useful resource from the switching side of things


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Ben Moore

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This is what I was kind of after, specifically where it mentions fifo for the ap backhaul interface.

Cisco  documentation states in it's ap config guide

They do only FIFO queueing on the Ethernet egress port.


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Ben Moore

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I got to the bottom of this eventually when time permitted. We use DSCP markings for voice ef (46) and video af 41 (34) and using a classifier map only.

Classifier Map in use shown below

Client to Inbound behaviour

Client Marks voice and video using window qos mappings as mentioned above.  The Wlan driver uses DSCP and then puts both into the into the video queue when transmitting to the AP. Original Client added DSCP value is correctly maintained onward into the WAN/LAN.

AP to Client

Voice dscp 46 gets to AP via ethernet interface and classfied as voice due to classfier map. It then gets put into Voice Queue.  As a side note DSCP appears to get remarked to 48.

Video af41 get to AP and classfied and then put into Video Queue I suspect this will also have its dscp value remarked also. I just cant find my testing captures at the moment. 

I hope this proves useful, I raised a few support calls telling me to use a marker map. It does not appear to need a marker map at all. 

I hope this helps someone.