How to make VoIP work over 2 aggregated cable internet connections

Posted on 2014-08-18
Last Modified: 2014-08-22
I have an office that requires a higher capacity connection and in an effort to save money we have ordered a second Time Warner cable internet connection into the building and we have used a Watchguard XTM515 to aggregate the 2 cable modems. I have also weighed them 1:1 since both connections are 50/5.
There seems to be one negative side effect of this and it's interfering with our VoIP system. We have an Altigen server that's collocated in a data center  that's responsible for this particular office. The phones will just randomly drop their registration and then they are out of commission of course. When initially implemented this seemed to work fine for days and then all of a sudden I was notified that randomly phones will unregister and stay down for long periods of time. There are about 100 other phones on that server and all of them are working just fine. Also it's a pretty standard configuration on these phones as well. The process of distributing internet access over these 2 connections seems to be causing the issue. The XTM515 has enough muscle under the hood to handle this office, it never runs out of resources.  The solution here would be to just send all the VoIP traffic strictly through one of the interfaces but does anybody have any ideas as to how to do this? I thought about implementing a SIP ALG policy but as I'm watching traffic I can't see any SIP traffic (We are using SIP trunks) so that policy may not work. Please advise.
Question by:aackar
    LVL 20

    Accepted Solution


    Doesnt look like there's a setting on the Multi-WAN part to set it up. You'll probably need to configure a Static Route to your Altigen server through one gateway. Page 195 on manual (page 240 on adobe reader)

    Author Comment

    I tried policy based routing and that didn't work either, it seems that as long as multi-WAN configuration is enabled VoIP does not like it.
    LVL 20

    Expert Comment

    That's not the way the manual describes it.

    Pg. 229
    When you configure multi-WAN with the Round-robin method, the XTM device looks at its internal
    route table to check for specific static or dynamic routing information for each connection. The route
    table includes dynamic routes as well as static routes you configure on the device. If no specified route
    is found, the XTM device distributes the traffic load among its external interfaces

    Try adding that static route. Network > Routes > Add

    Route Type - Static
    Destination Type - Host IPv4
    Route To - <IP Address of Altigen server>
    Gateway - <IP Address of your ISP gateway>
    Metric - 1

    Author Comment

    before I try this why do you think that this will work? Out of all the phones in the office about half work and the other half doesn't and then a few hours into the work day they switch, the ones that worked stop and vice versa. it's not like they can't fine the collocated server, all phones show as registered on the server at all times, it's just when you call them you can't hear them (and only some of them).What makes you think a static route is going to do anything?
    LVL 20

    Expert Comment

    Could be several things that are happening here, but it seems to me that it was working before and now you have half your phones not working...

    Putting things back to how they were is a good starting point. Configuring the static route out your old ISP to your Altigen should put things back to how they were and get you up and running.

    Just make sure to point the static route out the old ISP gateway, not the new one.

    Then if this works, you can try troubleshooting after hours to pinpoint the exact problem. For one, you can change the static route out the new ISP gateway and see how the phones work there.

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