SCN w/ PIX Firewalls

[Shine52]

I have a multi site SCN(w/ CVM, and all sites are 3.0(69)) set up w/ ADSL circuits(all from the same carrier), all via VPN through Pix Firewalls. I am having voice quality issues, especially w/ VM messages. One site in particular has become a major problem. I have a 412 at them main site, and a point 2 point T1 connecting to a 406 where the VM resides. ALl the other sites are IPO smalls connected via ADSL.

-Allow direct media path is unchecked on all IP routes and I am using g.729(a)8K cs compression mode.
-I have run all fix ups on the PIX's. Are there any other things I can try on the PIX.
-Should this work well, mediocre, not so well?
-Any help would be greatly appreciated.





Figure it out damn-it!

 

[dizzyphil]

When you say especially w/vm messages, what is going on? Is it not recognizing DTMF, cutting messages, choppy voice recordings? And how is the setting on each unit and versions?

Dizzy

 

[Shine52]

Mostly it is in regards to choppy voice recordings, and cutting messages. If I listen to the messages from the host VM location, the VM's seem to be fine. I can't say all. I am also experiencing "tinny" conversations via 4 digit dial.

The Pix's are 501, version 63(4).

Figure it out damn-it!

 

[dizzyphil]

What is your ping rate between each site? what is the bandwidth between your sites? how many calls can you estimate between each site. One thing to remember about vpn is, vpn adds substantial overheads to existing traffic. Basic G729 VoIP over Ethernet requires 30Kbps, the same over a VPN link consumes 56Kbps

dizzy

 

[Shine52]

Avg ping rate is 15ms. Which is great and why its so frustrating. There is 1.5MB both ways. We have recieived traffic reports and do not see any abnormal behavior or even any spikes over 500k. This is why I believe the IPO is not the problem, and the lag is existing in the VPN.

So what your saying in regards to traffic and overhead. Does the a call to VM for instance, occupy 56k 1 way, and simultaneously occuping another 56k back? Or is it just 1 way?

Thanks for you rinput Dizzy.

Figure it out damn-it!

 

[dizzyphil]

Try looking this up in your firewall routers. See if you can disable h.323 packet inspection or something of that nature, test and let me know.

Dizzy

 

[diannacone]

Are you using any Echo Cancellation? Like a VCM card. This will not take care of your voice quality but may take care of your "tinny" conversations.

The other thing that you have to remember with any VPN tunnel doesn't matter if it is a PIX, Sonicwall or even a home user using a VPN Client, there is no QOS settings that you can set. Once you are on the Internet your open to issue's. Truly the best way is Point to Point. Another possibility is an MPLS circuit which is basically a Point to Point VPN however there is an agreement with the provider, and they will provide some sort of QOS for you.