recently I came across a missing “feature” in the MX routers. I am working in Papua New Guinea, where many technical things are very unreliable. The internet in PNG is not very stable. In one of our location we have a Panasonic IP-Phone System (TDE-600) that is using VOIP providers. We have a dedicated MX-60 for the phone system.
On the MX-60 we use two ISP. On WAN 1 (our primary) we have a low latency internet connection, on WAN 2 a VSAT internet connection (slow and high latency). The MX60 use WAN 1 as the primary internet connection and the WAN2 port only as backup. Also our Panasonic IP Phone System has two IP addresses, one that is be using for the VOIP signalling and the other one for the VOICE DSP that is handling the pure voice traffic during the conversation. Now here is the problem. As long as WAN 1 works everything works fine. The VOIP signalling traffic and the VOICE traffic itself goes through WAN 1 and we can make and receive phone calls. When WAN1 fails the MX forces all traffic immediately going to WAN 2. That works fine. However, soon as WAN 1 comes back online the MX routes all new traffic to WAN 1, the existing traffic stays on WAN 2. This was designed in order not to interrupt existing TC/IP flow. In our case the VOIP signalling traffic stays on WAN 2 (because the phone system contacts the VOIP provider constantly). If I now try to make a phone call the new VOICE traffic (from the second IP of the phone system) is routed through WAN 1, but the signalling traffic stays on WAN2 and this caused that I can’t hear the other party. The only way to fix this problem is manually disconnect WAN 2 and then connect WAN 2 again. This force the MX to use WAN 1 again as primary port for all traffic. One of the MX technician told me that I need to request the “feature” to force the MX to route all traffic immediately to the main WAN port when it comes back online.
Customer support service by UserEcho