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CS410 10-15 seconds of silence


Worm78
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I have a cs410 hooked direct to a public IP for testing. About 2-3 times a day I get complaints of the person on the other end hearing us but us only hearing silence on our end for 10-15 seconds. If you wait audio does go back to normal. I'm using a trunk through Teliax. Any ideas?

 

Happens on several phones.

 

 

Please use the information on this web page when you address the support.

Version: 3.0.0.2899 (Linux)

License Status: cs410

License Duration: Permanent

Additional license information: Extensions: 8/10 Accounts: 14/20

Working Directory: /pbx

IP Addresses: eth2 x.x.x.x 255.255.255.0

eth1 1.1.1.1 1.1.1.0 255.255.255.0

eth0 192.168.10.200 192.168.10.0 255.255.255.0

lo 127.0.0.1 127.0.0.0 255.0.0.0

default 96.11.x.x

 

MAC Addresses: xxxxxxxxxx

Calls: 168/35 (CDR: 203) 0/0 Calls

SIP packet statistics: Tx: 139657 Rx: 128098

Emails: Successful sent: 39 Unsuccessful attempts: 0

Uptime: 12 19:24:44 (4467 4957440-0) WAV cache: 0

Media CPU Usage: 100%

0%

0 24

 

 

Thanks

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Issue is still there. Any other ideas? Anything specific to look for in the log and if so at what log level?

 

When it comes to media related problems, it usually makes sense to get a PCAP trace and analyze it with Wireshark (AKA Ethereal). The CS410 has a program called tcpdump installed which can create PCAP files (also with UDP packets, the name is a little bit misleading). You need to log into the CS410 by secure shell for that and operate on Linux level.

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I placed my laptop on the local network and installed xlite. I called a 800 number job hotline recording until the issue started. I started a wireshark snapshot and let it run until the audio of the recording came back. I have attached both. It looks like i'm getting a udp checksum error but i just don't know what I'm looking at well enough to know the issue. I also attached a normal portion of a noneffected call.

 

Also to note they are using the phone more often and it seems to be happening alot more then I first thought. I also seem to have the issue at the same time on multiple phones. PC's are on the local side of he network behind (same side) a netgear router. Lan port is direct to the public side with its own ip. Just curious should I have anything in the gateway section of the local ip settings. I seem to recall taking that out to fix a ntp issue. I think this was on purpose to keep the trunk going out the correct port but want to make sure while I'm asking questions.

 

Thanks

pcaps.zip

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Most typical routers do see SIP as a unique protocol. Typically users create a PORT Forward range tha include the range of ports listed on the settings, ports page. these are forwarded to the internal PBX if it's not on it's own public IP.

 

Also forwarding 5060 (SIP)

Port Range Start: 49152

Port Range End: 65534

 

But since you appear to have a router in front of the PBX, you can test this yourself by simply moving the PBX to the Public IP on the router and retest... MTU values can also cause problems. These can be exacerbated with using long SIP vs. short SIP headers.

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Not sure if I explained my setup correctly.

 

CS410 -- Wan port goes to public switch/router. Lan port goes to local 24 port switch.

 

Netgear internet router -- Wan port goes to switch/router. Lan port goes to local 24 port switch.

 

Both devices have their own public IP. All SIP devices on lan have their reg/gateway pointed to the local IP of the cs410.

 

Thanks

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I placed my laptop on the local network and installed xlite. I called a 800 number job hotline recording until the issue started. I started a wireshark snapshot and let it run until the audio of the recording came back. I have attached both. It looks like i'm getting a udp checksum error but i just don't know what I'm looking at well enough to know the issue. I also attached a normal portion of a noneffected call.

 

Also to note they are using the phone more often and it seems to be happening alot more then I first thought. I also seem to have the issue at the same time on multiple phones. PC's are on the local side of he network behind (same side) a netgear router. Lan port is direct to the public side with its own ip. Just curious should I have anything in the gateway section of the local ip settings. I seem to recall taking that out to fix a ntp issue. I think this was on purpose to keep the trunk going out the correct port but want to make sure while I'm asking questions.

 

I see a lot of UDP checksum errors going into the CS410. Maybe the CS410 (Linux) rejects them on the operating system and they do not count as traffic.

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Not sure what you mean PBXNSIP.

Any other suggestions for troubleshooting?

 

I added the device to a new sip trunk and the issue remains. Still same company. Andy suggested monitoring the WAN port which I will do tomorrow and then post a new pcap file.

 

All users are using X lite. Windows firewall has an exception for the program. Any known issues with this soft phone? I have searched their forum with no luck.

 

Thanks,

Brian

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Not sure what you mean PBXNSIP.

 

Well, my Wireshark shows that the UDP packet checksums are incorrect... The reason is defintively not the ITSP, as the UDP checksums are generated by the router (as UDP is layer 3). Maybe something stupid like bits flipping around, bytes being chopped off, or just a bad firmware on the router. Checksums are there for a reason and they should be correct!

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Thanks for the quick reply.

 

I will check the firmware and see what else I can do to eliminate the errors.

 

 

Well, my Wireshark shows that the UDP packet checksums are incorrect... The reason is defintively not the ITSP, as the UDP checksums are generated by the router (as UDP is layer 3). Maybe something stupid like bits flipping around, bytes being chopped off, or just a bad firmware on the router. Checksums are there for a reason and they should be correct!
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Agreed, other problems must exist as these malformed packets are LAN based and would not traverse the WAN. I suspect the culprit is spread across several contributing factors; the hosts for X-lite, switches and routers, and without some advanced knowledge and experience troubles like this can linger as one plays the guessing game. SIPp 3.1, Wireshark are excellent tool to discover the exact cause. Laura Chappell with http://www.packet-level.com offers some tremendous tools and training on Packet Decoding and use of WireShark. While her daily rate is $$$$$$ her tools and training programs are very affordable. I also suspect no TOS/COS/QUEUING packet control exists on any device.

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I'm still having issues if anyone has any ideas. I moved the lan port of the PBX from the router which is attached to the switch, to directly to the switch. All four router ports are open on the lan side as it is just a home type router. It seems to help the checksum errors a bit but I'm still getting them during silence. I used to always get the checksum errors and even more so during silence, however now I mainly only get them during it connecting and then it comes in with long silence periods. I did change xlite to conserver bandwidth during silence periods and this helped a bit too. Still having the issue though. Nothing so far has impacted the original issue in duration or quanity.

 

I'm attaching a cheesey drawing to help with the layout.

 

Any other ideas?

 

GW on the lan side pbx connection settings is removed. I run a Workstation version of pbxnsip on my personal network and I see the similar checksum errors in wireshark.

 

 

Thanks

SKMBT_C45108090312590.pdf

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I first suspect the trouble to be the DSL / Modem Switch. It's like a 1/N packet scheduler and know nothing of QOS.

 

What's likely contributing to this is the DHCP server is handing out itself as the gateway. Invites may contain public IPs and they may attempt to pass through the router, as opposed directly back to the PBX. Does the Softphone contain settings for a registration and proxy server? If so make them the same...

 

You may want to make the PBX the LAN DHCP Server.

 

Packets may very well be outbound to the PBX through the Router to the WAN side of the PBX....

 

We prefer not to place the WAN side of the PBX on a Public IP, Instead we use SIP AWARE routers and router SIP Traffic to the PBX and allow the router to Shape the traffic to allow WEB surfing on the LAN. I think you are nearby, and would be happy to help put this issue to rest. Cheers.

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Something else that comes to mind, since you are using softphones, and likely DHCP from the Router, as a test to isolate internal/external issues. set two PC's to static IP's, manually register the softphone, with no Gateway and make calls to each extension. You can turn off the router, and I suspect the call troubles will disappear. I would then register a remote phone to the PBX and make calls among those extensions. Again I suspect the troubles will disappear. This likely will confirm the issues previously mentioned, or lead you to suspect the ITSP is contributing the problem.

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  • 3 weeks later...

Update:

 

 

Issue is still happening but not as much. I connected via wireless and tried and couldnt get it to happen in a time frame in which it normally happens 5 times so I decided to run a wireshark.

When on wireless I don't get checksum errors on my wireshark dump. If on the lan I do. I get these same checksum errors on my personal working system as well. I have attached both.

 

I also removed the switch from the picture to try to eliminate the check sums. They were still there. I then removed the router and only used the switch and the check sums remained in the picture.

 

 

other changes

I have X lite pointed directly to the pbx for DNS to help ensure the router is not being used.

 

I also setup a snom desk phone and it seems to be working well but the user hasn't used it heavy. Hopefully a full week of using the phone will show if the issue is gone or not or only while using xlite. I have also used the dump feature on X lite but can't get the problem to happen during that of course.

 

 

Any ideas from looking at the calls made during the attached wireshark dumps?

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  • 2 weeks later...

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