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Outbound calls: Enterprise Mediation Pool does not round robin calls to PSTN gateways RRS feed

  • Question

  • Hello,

    I have  the following configuration:

    • Lync Enterprise pool with CU02 installed.
    • 2 dedicated Lync Mediation role servers(an enterprise Editon Mediation pool composed of 2 servers) with CU02 installed.
    • For load sharing purpose, I have configured 2 PSTN gateways for the same outgoing route.

    When making outbound calls towards PSTN Gateways, I would expect that Lync load balances the trafic equally to the 2 PSTN Gateways with round robin mechanism.

    For example, I would expect to have calls routed to PSTN Gateway as: 1-2-1-2-1-2-1-2-1-2... (1 means call routed to Gateway 1 and 2 means call routed to gateway 2).

    The actual results I got from test calls are: 2-2-2-1-1-1-2-2-2-1-2-1-2-2-1-1-1-1-1-2-1-1-1-1-2-2

    Sure that the calls seem to be a kind of load balanced but not really round robin as I expect to get.

    Any one else has observed this behavior?

    Thanks.

     

    Thursday, August 4, 2011 7:28 AM

Answers

  •  


    From what I understand Mediation Server maintains primary and secoundary lists for GWs based on their states
    the gateway states are:
    • Up
    • Down
    • Less-Preferred

    These states are computed based on several things
    Sip Options Response
    Other responses greater than 300 etc

    The lists are constently updated.  And when a call is being routed the GW at the top of the primary list is selected.
    This  may cause this kind of behavior.

    But with large number of calls the distribution of calls should be even.

     

    -Santosh


    Microsoft Unified Communications Team
    • Proposed as answer by Santosh_More Wednesday, September 28, 2011 9:59 AM
    • Marked as answer by Sean_Xiao Wednesday, September 28, 2011 10:31 AM
    Monday, August 29, 2011 9:52 AM

All replies

  • Where do you set the configuration to work with round robin as expected?

    Maybe the actual result you got is caused by that the calls are routed to gateway according to voice policy in the lync control panel.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.
    Friday, August 5, 2011 9:28 AM
  • Hello,

    I have only configured 2 PSTN Gateways for the same route. This should load balance the trafic from the Mediation Pool to the 2 PSTN Gateways right? The problem (if it is a problem) is that the way the Mediation pool load balances the trafic to these 2 PSTN Gateways is not Round Robin manner.

    Jens Trier Rasmussen's blog seems to explain that the Mediation performs a Round Robin load balancing but the problem is that my test results don't confirm this scenario and I have found nothing inside the Microsoft documentation explaining clearly how Mediation pool load balances trafic to PSTN Gateways configured inside the same route.

    http://blogs.technet.com/b/jenstr/archive/2010/10/12/outbound-routing.aspx

     

    Friday, August 5, 2011 7:24 PM
  •  


    From what I understand Mediation Server maintains primary and secoundary lists for GWs based on their states
    the gateway states are:
    • Up
    • Down
    • Less-Preferred

    These states are computed based on several things
    Sip Options Response
    Other responses greater than 300 etc

    The lists are constently updated.  And when a call is being routed the GW at the top of the primary list is selected.
    This  may cause this kind of behavior.

    But with large number of calls the distribution of calls should be even.

     

    -Santosh


    Microsoft Unified Communications Team
    • Proposed as answer by Santosh_More Wednesday, September 28, 2011 9:59 AM
    • Marked as answer by Sean_Xiao Wednesday, September 28, 2011 10:31 AM
    Monday, August 29, 2011 9:52 AM
  • I have noticed similar behaviour with two gateways added to my routes.   In my case both gateways were available and Lync was not load balancing between them even though both were available.  Lync was using the PSTN Gateway that was NOT marked as default in the Topology builder as well.  I am looking for more clarification around this behaviour.  If anyone has more info please advise.


    Dino Caputo, BA | MCSE | MCTS:OCS http://www.ucguys.com

    Tuesday, April 24, 2012 12:26 PM