[voip] 3CX Dropping

[lmrogers]

Morning,

 

We are suffering at the moment with really bad phone lines and calls cutting out mid conversation. This is only on external calls.

 

Our SIP trunk provider cannot see any issues with the trunks and from Wireshark traces I have sent over they seem to think that the issues are coming before it hits them. I have the 3CX server hosted on our Hyper V Cluster and all phones on their own VLAN.

 

I have QOS on our internal HP switching for this VLAN and have also give VOIP Traffic priority and a guaranteed 10MBps on our Smoothwall.

 

We are still having these issues and I'm not completely convinced that our Smoothwall is handling the traffic correctly.

 

Does anyone have any pointers on this at all?

 

Any help now is greatly appreciated!

 

Thanks,

[forkies]

Morning,

 

We are suffering at the moment with really bad phone lines and calls cutting out mid conversation. This is only on external calls.

 

Our SIP trunk provider cannot see any issues with the trunks and from Wireshark traces I have sent over they seem to think that the issues are coming before it hits them. I have the 3CX server hosted on our Hyper V Cluster and all phones on their own VLAN.

 

I have QOS on our internal HP switching for this VLAN and have also give VOIP Traffic priority and a guaranteed 10MBps on our Smoothwall.

 

We are still having these issues and I'm not completely convinced that our Smoothwall is handling the traffic correctly.

 

Does anyone have any pointers on this at all?

 

Any help now is greatly appreciated!

 

Thanks,

 

We had an issue like this with our Smoothwall. This was confirmed when we moved from NEC to 3CX and the issue persisted. We actually found we were dropping packets for a few seconds every so often on the WAN link and that the port on the Smoothwall was showing down then up instantly. Smoothwall failed to resolve and I ended up spinning up PFSense to route all our SIP traffic and essential services through, not had a single issue since. I only route filtering via the Smoothwall now as that has less impact. Will be moving away from Smoothwall next year with our renewal due.

 

I would suggest checking the system logs on the Smoothwall around the time of the loss of voice and see if it shows your WAN interface dropping and if so good luck getting it resolved without doing what we have done.

[mdrabble]

Have you got IDS enabled on the external IP address used for your 3CX?

 

I found that caused issues and after disabling it I’ve had no issues.

Edited October 17, 2020 by mdrabble

[lmrogers]

We had an issue like this with our Smoothwall. This was confirmed when we moved from NEC to 3CX and the issue persisted. We actually found we were dropping packets for a few seconds every so often on the WAN link and that the port on the Smoothwall was showing down then up instantly. Smoothwall failed to resolve and I ended up spinning up PFSense to route all our SIP traffic and essential services through, not had a single issue since. I only route filtering via the Smoothwall now as that has less impact. Will be moving away from Smoothwall next year with our renewal due.

 

I would suggest checking the system logs on the Smoothwall around the time of the loss of voice and see if it shows your WAN interface dropping and if so good luck getting it resolved without doing what we have done.

 

Thanks for the info, I will have a look more at the Smoothwall logs. Out of interested how did you setup your pfsense? I am going to be moving from Smoothwall myself next year. Their support has been awful recently.

[lmrogers]

Have you got IDS enabled on the external IP address used for your 3CX?

 

I found that caused issues and after disabling it I’ve had no issues.

 

So I have IDS enabled on the External WAN port which includes the external IP Address for 3CX. Do you know of a way to remove just this 1 IP address from that policy?

 

Thanks

[mdrabble]

I meant IPS - not IDS (didnt have access to smoothwall when I posted the message and as they almost the same letters I got the wrong ones......)

 

I have port forward rules configured for just 3CX ports and changed the IPS settings on that rule. - Network -> Port Forwarding

[lmrogers]

I meant IPS - not IDS (didnt have access to smoothwall when I posted the message and as they almost the same letters I got the wrong ones......)

 

I have port forward rules configured for just 3CX ports and changed the IPS settings on that rule. - Network -> Port Forwarding

 

Oh right, yeah I have IPS disabled on the port forward but still have the issue.

[mdrabble]

I also don't have any SIP settings configured on smoothwall at all - I just installed server, added IP, Rules etc

[lmrogers]

I also don't have any SIP settings configured on smoothwall at all - I just installed server, added IP, Rules etc

 

So I have installed the 3CX server. Added the port forward under Network -> Port Forwards. Added firewall rules from the SIP Trunk IP to server IP for 3CX traffic. Made sure that under Services -> SIP it is not enabled, as that was causing SIP ALG fails when running the firewall check in 3CX and I'm pretty sure that is all thats needed. Unless I have missed something.

[mdrabble]

That basically what I did - I also set up a SNAT rule do my 3CX has a dedicated IP for incoming and outgoing traffic.

[lmrogers]

That basically what I did - I also set up a SNAT rule do my 3CX has a dedicated IP for incoming and outgoing traffic.

 

Yeah I have set that up as well. I shall have to keep looking at try and figure out whats going on.

[lmrogers]

We had an issue like this with our Smoothwall. This was confirmed when we moved from NEC to 3CX and the issue persisted. We actually found we were dropping packets for a few seconds every so often on the WAN link and that the port on the Smoothwall was showing down then up instantly. Smoothwall failed to resolve and I ended up spinning up PFSense to route all our SIP traffic and essential services through, not had a single issue since. I only route filtering via the Smoothwall now as that has less impact. Will be moving away from Smoothwall next year with our renewal due.

 

I would suggest checking the system logs on the Smoothwall around the time of the loss of voice and see if it shows your WAN interface dropping and if so good luck getting it resolved without doing what we have done.

 

I've just been physically in the server room looking for other bits and was actually watching our smoothwall s8 appliance for a bit and kept seeing the WAN interface dropping network activity. So that would probably explain the issues. Just got to try and get a fix now.

[chrisjako]

Did you ever get to the bottom of the issue ?

[Davit2005]

Check SIP ALG settings on firewall and try disabling it.

 

Always a good idea to have voice on it's own vlan as others have done, this stops noisy traffic causing interference.

Edited May 17, 2023 by Davit2005

[lmrogers]

Did you ever get to the bottom of the issue ?

 

Yeah the Smoothwall kept randomly dropping the WAN interface for split seconds so it wasn't noticeable on general web usage but affect the call audio. I just stood up a pfsense VM and re-routed all the Phone traffic through that to the WAN until I replaced the Smoothwall.

[DGardiner]

We had to get our smoothwall set to not auto negotiate its link speed to the isp router in the past they kept jumping to/from 100/1000.

 

I cant remember if i got the ISP to do this or if i got smoothwall though as weve since moved it to the isp datacenter