Media Traffic Routing RRS feed

  • Question

  • Hello!

    We're installing Lync for one of our customers and run into problems with media traffic routing inside Lync environment.

    One of the customer requirements is to record Lync calls for a limited group of users. Main recording scenario is to record incoming calls from PSTN (we using AudioCodes Mediant 1000 media gateway and dedicated Mediation Server for PSTN connection), all recorded users are sitting inside corporate network. We're using Live-PA Lync Call recording solution and while configuring it we found very strange media traffic routing behaviour. Lync randomly routes media traffic for some calls through Edge Server. We know it because Live-PA has problems with recording calls which goes through Edge. As a result we cannot correctly record such calls.

    So the question is why Lync uses Edge for routing media traffic for internal users (in fact incoming calls from PSTN) and is there any way to exclude Edge from this process? This will allow us to record all calls correctly.

    Long live rock'n'roll !!!
    Friday, June 24, 2011 3:03 PM

All replies

  • Mckey

    Are the users who get calls routed through the Edge on your internal network? Are they registering with the internal pool or are they for some reason registering as if they are remote users? Perhaps they have manual client connection settings that are incorrect or they have issues with DNS? Are all calls to these users going via Edge or is it intermittent?

    If it is consistently one group of users, you could set their client connection config to manual but only specify an internal pool address and no addresses for remote access.


    If a post is helpful, please take a second to hit the green arrow on the left, or mark as answer, thanks

    MCITP: Lync, Exchange 2010 & Server Administrator

    Friday, June 24, 2011 3:53 PM
  • Hi Mike,

    Yes, all users that recieve the calls are sitting on the internal network and register with the internal pool. They even have external connectivity turned off. Their clients are configured for automatic automatic discovery of Lync servers. We tried to set connection settings manually and use only front end address, no external server - that didn't helped. All DNS records are in place and correct.

    I'll say even more: a certain user may recieve one call through front end - and it is recorded correctly - and second call might go through edge (and recording fails). The next call migth be routed through front end again. We didn't see any logic here, just random call routing through edge or front end.

    We checked everything and cannot find the answer.

    So the question remains - why Lync sometimes uses edge for routing calls to internal users? And how to get rid of it?

    Long live rock'n'roll !!!
    Saturday, June 25, 2011 4:21 PM
  • Very strange behavior! How about disabling the user for right to remote access, would this stop them routing via the Edge? Just as an aid to troubleshooting this issue, not as a permanent solution.


    If a post is helpful, please take a second to hit the green arrow on the left, or mark as answer, thanks

    MCITP: Lync, Exchange 2010 & Server Administrator

    Sunday, June 26, 2011 9:53 AM
  • Already tried it and no luck. Even if external access for user is disabled Lync still sometimes use edge to route media to the client...


    We tried to contact Live-PA about this issue and they say that they're aware of such Lync behaviour but don't know how to deal with it.

    Long live rock'n'roll !!!
    Sunday, June 26, 2011 1:18 PM
  • If the peer-to-peer media stream can't get from one internal client to another directly (like for instance due to a software firewall on the client or some traffic restriction between the two clients, it seems to proxy that media traffic through the internal edge interface.  I'm not sure if it also does this if the subnets are not determined to be internal (listed on the Subnet tab of the Network Configuration in the control panel).


    Wednesday, June 29, 2011 5:14 AM
  • You should read Elan Shudow's blog on media negotiation: http://www.shudnow.net/2010/12/06/lync-server-2010-port-ranges-and-audiomedia-negotiation/

    Lync will use the edge, even for internal calls, if there are issues preventing peer-to-peer media connections. If you look at the SIP invite / SDP info for every call, the edge server is listed as a candidate. Lync will spin up an attempt to the edge right away just in case one party is remote, or one party can't be reached peer-to-peer. Lync does this at the beginning of a call so as not to introduce delay if in fact one of the parties is external.

    The only real way to stop this is to not specify an AV edge server in you pool config. This would be bad, though, because it would break all external AV.

    I'd suggest looking at the network path between the two callers. I'd also check windows firewall on the two callers machines.



    Matt McGillen, PointBridge - https://blogs.pointbridge.com/Blogs/mcgillen_matt/default.aspx
    Thursday, June 30, 2011 12:38 AM