10-02-2016 07:44 PM - edited 03-13-2019 09:37 PM
Dear VOIP Expert,
I have a doubt with VOIP. I have a serial link which is L3 MPLS VPN . Now, I have changed to L2 VPN IEPL Link.
At this time, I have one problem with VOIP. I can not call to international. So I roll back to serial it is back to normal. And then I try again to IEPL link .
Still same error. So I have try several time . Still same error. In the meanwhile , I take the packet capture on my WAN Router interface.
I saw UDP Packet are being fragmentation on IEPL link. When I change to Serial link there is no fragmentation. So, I suspect that SIP server do n't allowed the UDP fragmentation.
How can I solve this problem , My found is correct or not.
How can I find root cause for more specific troubleshooting.
Thanks and Regards,
Solved! Go to Solution.
10-04-2016 06:17 AM
You could try carrying SIP signalling traffic over TCP instead of UDP, like the article suggests. You would do that by configuring 'session transport tcp' on your dial-peers. It may not be supported by your service provider but worth a shot.
10-03-2016 09:51 AM
Currently I am using serial link that we called as IPLC which is L3 MPLS VPN link. I am using both data and VOIP traffic on this link. So far ok but Link bandwidth is only 2 Mbps.
So we had hire 10 Mbps link from other ISP. That link technology is totally changed , they called as IEPL L2 VPN link. On this L2 VPN link , I also use data and VOIP traffic . It is ok but I have encountered the problem with one CUCM can't call to international call. In the meanwhile , some voip pattern is still ok. But only that CUCM can't call to international call. In our Voice gateway have only one Public IP address. In the mean while , I can call international call with other VOIP Pattern. So I don't suspect to Routing issue.
When I roll back to serial link call is back to normal. I have tried several time change to IEPL link and Serial link , it is still same error.
So I had capture the packet on both serial and IEPL link . In the capture file, I saw ipv4 fragmentation on IEPL link . And I saw the fact SIP-UDP can't accept UDP fragmentation . I am not sure but I found on this blog.
http://blog.csrpswitch.com/sip-udp-fragmentation-and-kamailio-the-sip-he...
Thus, I suspect this IEPL link is drop my VOIP packet.
Please let me have your opinion what should I check for my problem.
Thanks you
10-04-2016 06:17 AM
You could try carrying SIP signalling traffic over TCP instead of UDP, like the article suggests. You would do that by configuring 'session transport tcp' on your dial-peers. It may not be supported by your service provider but worth a shot.
02-27-2017 07:01 PM
This answer is absolutely correct answer. I have change to protocol to TCP instead of UDP in voice gateway.
Very much thanks Mr. Evgency Izetov
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