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QoS Config for Microsoft Lync 2013

QoS Config for Microsoft Lync 2013

New Contributor
Does anyone know how to configure QoS for Microsoft Lync? I know there is a Lync SDN for Dynamic QoS configurations and we will be using that in the coming months but I need something that i can configure right now to alleviate QoS issues. We set up a conference call between 2 sites over a VPLS circuit provided by AT&T. The Quality of the call was horrible. We have DSCP enabled on all ports and we have qosprofiles configured for audio and video. qp4 is video and qp5 is audio. The VPLS port is hard coded to 100Mbps full duplex. The circuit itself is a 50Mbps circuit. While in a call i see consistant packet drops when i run the command show port 1:24 congestion. i also see that QP5 and QP1 are the packets that are causing the congestion. QP5 causes most of the congestion.

This is what I have so far for configs:
configure ports 1:24 auto off speed 100 duplex full
configure ports 1:24 shared-packet-buffer 30

configure qosprofile QP4 maxbuffer 100 weight 1 (Default)
configure qosprofile QP5 maxbuffer 100 weight 1 (Default)

configure qosprofile QP1 committed_rate 24900 K peak_rate 50000 K ports 1:24
configure qosprofile QP4 committed_rate 20000 K peak_rate 40000 K ports 1:24
configure qosprofile QP5 committed_rate 5000 K peak_rate 8000 K ports 1:24
configure qosprofile QP8 committed_rate 100 K peak_rate 3000 K ports 1:24

configure diffserv examination code-point 26 qosprofile QP5
configure diffserv examination code-point 34 qosprofile QP4 (Lync Video)
configure diffserv examination code-point 40 qosprofile QP4
configure diffserv examination code-point 46 qosprofile QP5 (Lync Audio

show qosprofile port 1:24
Port: 1:24
QP1 CIR = 24900K PR = 50M MaxBuf = 100%
QP4 CIR = 20M PR = 40M MaxBuf = 100%
QP5 CIR = 5M PR = 8M MaxBuf = 100%
QP8 CIR = 100K PR = 3M MaxBuf = 100%

show qosprofile
QP1 Weight = 1 Max Buffer Percent = 100
QP4 Weight = 1 Max Buffer Percent = 100
QP5 Weight = 1 Max Buffer Percent = 100
QP8 Weight = 1 Max Buffer Percent = 100

one thing that I saw in the ports information details was this setting
QoS Profile: None configured

I'm not sure why the QoS profile is not configured if I have all these configurations above.

VPLS Bandwidth per sites
Site 1: 50Mbps
Site 2: 50Mbps
Site 3: 50Mbps

We have Lync deployed to a few users and in all of our conference rooms. If anyone could help me with a QoS Configuration that can hold us over until we get the Lync SDN deployed, that would be great.

New Contributor II
I just stumbled across a document for this that I couldn't find before when I specifically went searching. It does an excellent job of explaining the pieces.

New Contributor
Since i have the CIR at 20Mbps and PR at 40Mbps, should the min and maxbw reflect that as well?

Extreme Employee
Hey Darren

Yes sorry it is .1p not .1Q was thinking to much to early in the morning. The min will guarantee the 1% bandwidth but the queue can burst up to 100% or to the highest bandwidth left over after satisfying all of the min values. So if you have two queues with a min of 1 % then any queue can burst up to 100% as long as there is no other traffic in those two queues. If there is traffic in those queues then any queue can burst up to 98%. Hope that makes sense.

If GTAC said to change the buffer that is fine just didn't want to change buffer for the fun of it 🙂

base on your queuing each queue will get a guarantee 1% of the ports bandwidth so you fullfil your 2Mmps.

I hope that helps

New Contributor
Hi Paul,
Thanks for the Reply. GTAC told me to raise the buffer speed because the congestion might be caused by traffic coming from ports with higher speeds. The tech did not give me much information on what percentage I should change it to so I only raised it 5%.

I am going to try and configure the min and maxbw on the port to
configure qosprofile egress qp4 minbw 1 maxbw 100 ports 1:24
configure qosprofile egress qp5 minbw 1 maxbw 100 ports 1:24
These numbers are based on a Lync Bandwidth Calculator that said I only need around 1Mbps for Video, less than 1Mbps for Audio, and A/V conference is 2Mbps. Now Lync doesnt have a DSCP code-point for Audio and Video, it seperates them to their individual code-points. Will this BW configuration satisfy the 2Mbps for audio/video or should I bump them both up to 2Mbps? Should the minbw and maxbw match my CIR and PR?

I have enabled diffserv examination on all ports and disabled dot1p examination on all ports. Is this what you mean when you say, "enable the DSCP examination on the ingress port"?

I am confused when you say disable .1Q examination. I cannot find anything in the concepts guide that says to disable .1Q examination. I found dot1p examination. Is that what you meant? If so, I did disable dot1p on all ports.