QOS over VPN

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I have a couple of Cisco 515e PIX firewalls with vr 7.2 of the PIX software,
which supports QOS through a VPN.  I have QOS configured but am having
issues with VOIP calls being dropped and sounding really broken up.  Someone
has told me that I need to change the QOS paramaters to fix the issue,
however I don't see how that could be the issue.

My question which I can't find a good answer too at the Cisco web site (or
anywhere else on the net) is simply this...
If I configure QOS that only applies on the inside interfaces of both Pix's
and it will have no effect on the actual tunnel trafic just on the tunneled
traffic at either end right?

I think the whole idea of VPN through an internet connection will never be
able to reliably deliver voice unless the ISP has some private network that
they can control.

Any thoughts or documentation on this issue would be appreciated.

Re: QOS over VPN
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Well, first, I must say that you are incorrect about not being able to ever
get good calls over the internet.  I personally have had home voip phone
service for about 3 years now and see no reason to go back to a traditional
telco line.  There are many other people hopping on board as well.  Look at
all the companies popping up out there, Viatalk,Vonage, Sunrocket, Skype,
Packet8 and many more.  Through vpn isn't much different.  You just need to
make sure that you have the horse power to process the packets quickly
enough.  I wouldn't think this would be a problem with the Pix 515.

That said, there are things to consider and it may be possible that you
don't have a good path from one end to the other.  QOS is very important.
I'm not sure how this is handled on the pix, but on the cisco routers, you
would do a pre-classify on the packets before they enter the tunnel, so that
the qos is carried across the vpn.  Otherwise, make sure that you reclassify
the packets as they are coming in.  Also, be sure that you are running
g.729.  If you are using g.711 that could be a big part of the problem.

Voip over the internet is here and it is, generally speaking, reliable.  So,
you'll just need to troubleshoot where the problem is occuring for you.

Hope that helps,


Re: QOS over VPN
On Mar 9, 7:36 pm, jagb...@gmail.com wrote:
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I don't know why you would run VoIP *through* VPN, but I've had very
good experience using ViaTalk through a WRT54G router having VPN
*alongside* VoIP using QoS, i.e. if VPN and VoIP traffic happen at the
same time, VoIP is given the preference.  VT tech support was very
helpful helping me through some initial issues, you might want to give
them a call and see if they support your setup, they might have run
into the same situation already.



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