Sniffing VoIP

[RobG2001]

I'm using Ethereal, a Mitel 5220 IP phone and a Catalyst 3550 switch. I am able to create sound files using the packets I've captured but they contain only one side of the coversation. Is there something I'm missing on listening to RTP?

Thanks
Robert

 

[mitelman]

Ok I don't know what your missing, but why would you want to do this anyway? If you're trying to record why not just do it the old fashion way?

 

[RobG2001]

I'm doing as an exercise in trying to learn more about VoIP. I like to understand everything on my network so when something goes wrong I can have a good idea of where the problem is. In addition, we've been running into some serious bugs in the 3300 where I've been asked (by Mitel in Canada) if I could capture some packets for them.

Let me know if you know the steps to get the 2-way conversation.

 

[biglebowski]

I don't know a great a deal about VoiP but are you sniffing both partys ip addrs

 

[RobG2001]

Specifically I'm sniffing everything on one port which should be getting the tx and rx from the phone.

 

[mitelman]

Robert, if tech support is asking you to collect the info they should also tell you what to collect, otherwise it's just another stall tactic to buy some time on their end. I have never been asked by them to collect packets so I can't help you on that, but I do know that they like to blame the network for the dumbest things. I just had another case of that today with some sets going down after an upgrade to 4.1.6.6. They accused the network guy of changing his switch ports.

Simon

 

[biglebowski]

I don't know if this is relevent but I know the call manager has problems with one way conversation if the call is put on hold or trnsfrd.

 

[RobG2001]

I'm a network guy and yes Mitelman, you're right. They did make me send them my Cisco configs and still blamed them network. Finally I made them plug the phones into the 3300 directly with a power brick and yet we were still getting the problem. After that, they said it could still be the network because the 3300 was connected to the network!! So after hours we plugged the phones into the 3300 and uplugged the 3300 from the cisco switch. Got the problem so they were finally convinced (I'm suprised they didn't blame the power source).

Interestingly the problems was with one-way conversations after using external paging. As of today they have two guys from Mitel here in Los Angeles trying to figure the software bug and others we found. We were supposed to cut over to the 3300 at the end of last year.

 

[mitelman]

The audio problem and paging is a known issue on the latest release. We have had a simalar issue here in Calgary and have got a couple patches from Mitel, but I don't know ifthe problem is totally resolved yet.

 

[RobG2001]

That is very interesting. Mitel is claiming we're the only one they know of having this issue. Do you have any specific info you could give me regarding the issue in Calgary on or off the list? I'd really like to tell them that xyz company also had a very similar issue that Mitel is aware of.

As a side note I was able to sniff the conversations finally with ethereal. Should be useful since the Mitel guy said they are looking to encrypt on the next release.