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Applied Bandwidth Limit & Call Quality Issues RRS feed

  • Question

  • Good afternoon

    I am working on some audio quality issues and I am looking for an explanation of where Applied Bandwidth Limit is calculated when CAC is disabled. The Source is "StaticMax" which as I understand it means it was not applied by policy - but was automatically determined. The explanation I found from MS was:

    This is the actual bandwidth applied to the given send side stream given various policy settings (TURN, API, SDP, Policy Server, and so on). This is not to be confused with the effective bandwidth because there can be a lower effective bandwidth based on the bandwidth estimate. This is basically the maximum bandwidth the send stream can take barring limits imposed by the bandwidth estimate.

    So, given that meaningless mess of an explanation -- how is it REALLY determined?

    The scenario is this -- 

    We have a caller who has an Applied Bandwidth Limit of 59k

    They have negotiated SILKWide with FEC, which requires 100k. The Bandwidth Estimates is 99k.

    http://blog.schertz.name/2014/11/silk-audio-in-lync-mobile-clients/

    It seems like the Applied Bandwidth Limit is definitely going to cause issues with SILKWide with FEC. 

    Can anyone explain how this works?


    • Edited by Mr. Cross Thursday, September 28, 2017 8:04 PM
    Thursday, September 28, 2017 7:22 PM

All replies

  • Hi,

    Poor quality, it may be caused by many issues:

    Device set up

    Whether the device is working properly and compatible with Lync

    Other user’s devices

    Network connectivity

    For “how is it REALLY determined?”

    In fact, StaticMax" which means a maximum hardcoded upper limit

    Friday, September 29, 2017 8:31 AM
  • It is calculated by client itself based on the available bandwidth on the network and rate the quality.If you have monitoring reports published you can verify this from call quality reports.The quality of the calls impacted with multiple things like network round trip,congestion,QoS. You may implement QoS for better performance of SFB.

    Here is the quality metrics.

    http://blog.insidelync.com/2012/06/a-primer-on-lync-audio-quality-metrics/

    CAC Details

    https://technet.microsoft.com/en-us/library/gg398529.aspx


    Jayakumar K

    Friday, September 29, 2017 12:03 PM