External User Quality of Experience


  • We have set up Lync with Edge servers, unfortunately conference with external users and audio and video quality is really poor even desktop share and other shares are not working as expected.

    I am unable to find out how much is the bandwidth requirement, Microsoft documentation is very vague  and does not give any clear information.

    How can I improve performance, is their a way to control bandwidth utilization, 

    what are best practices and is their a way to get good quality audio, its even poor than skype.

    giovedì 7 giugno 2012 06:32

Tutte le risposte

  • Call quality to the internet is always a tricky situation because you are competing with all sorts of other traffic going out to the internet.  So the simple places to start is to make sure that you aren't dealing with a full "pipe" to the internet.  Does the problem continue during off hours and are there any tools to ensure that there is available bandwidth?  You might have already gone down this road - just going in my normal order.

    Assuming we have bandwidth and calls even during off-hours are poor in quality typically the issue lies somewhere on the network side.  The amount of bandwidth required is not much.  You can see here:

    It's a heck of an eye chart - go to the very bottom for the numbers for planning purposes.

    So if you had an external user and they were calling an internal user, this is a P2P call and it would flow as RTAudio.  At most, you are talking 91Kbps for the call (that is with FEC - or forward error correction which only happens on networks where there is a great deal of dropped packets).  For planning purposes, I would tell you to use the Max Stream w/o FEC.  So as you can see a single call takes very little bandwidth and almost any internet connection should be able to handle this.  If you were doing a conference call, the person on the outside would be using G722, so they would be coming in at about 100k.  Video adds 260 for CIF (610 if using VGA).

    So this is bunch of background information but you asked is there a way to make it better.  First, do you have a monitoring server deployed?  If so, what are you seeing in the reports for call quality.  Do you see large jitter or dropped packets.  If you don't have a monitoring server deployed, you will want to get one.

    Next, check the connection from the edge server out to the internet and edge back in.  Do you see large number of dropped packets on any of the switch ports, etc.  What is the route that is being used?  Are services going through a server that doesn't make sense.  I had a client recently that used a TMG server as their router and all of their real time media was flowing through it - it was undersized and underperforming for their needs.  Once we took the TMG out of the mix, it was all better.

    There are ways in which you can implement Call Admission Control to an edge server, but if your problems are with low numbers of users this isn't going to help much.

    Lastly, desktop share is a pig on bandwidth.  It's just RDP.  It can burst to 1.5Mb.  So do calls without these and see what you get.  There isn't a way to throttle desktop shares, which is unfortunate, so step up in modalities and see if it's really just running out of bandwidth.



    Richard Brynteson, Avtex, Lync MCM

    giovedì 7 giugno 2012 12:35
  • Hi tanveer,

    Is there any update on the issue?  Would you please provide the informtion Richard asked?


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    • Modificato Kent-Huang venerdì 8 giugno 2012 09:46
    venerdì 8 giugno 2012 09:46
  • thanks Richard for your detailed reply. Currently we do not have any Monitoring Server in our environment an we are not planning for it soon. 

    I was wondering is there a way to limit the max number of connection for edge like what actually CAC do but I do not think CAC can limit it on edge it can only do it on sites. 

    I was planning to implement QE on edge and other server than i thought once packet goes out on internet its best effort only that whatever i get as cos marking it is not going to make any impact.

    it seems there is very less control when it comes to edge traffic.

    venerdì 8 giugno 2012 13:56