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Community Member

rtp header compression on VPN

Hi,

Is it possible to compress th rtp header on a VPN.

I use fastEthernet to connect with the IDU.I can't use the rtp-header compression on the FastEthernet interface.

In other case, how can I activate IP RTP Header-compression, if I use FastEthernet interface.

Thanks

6 REPLIES
Hall of Fame Super Gold

Re: rtp header compression on VPN

cRTP is supported only on serial interfaces. So you cannot enable it on VPN or fastethernet.

Hope this helps, please rate post if it does!

Community Member

Re: rtp header compression on VPN

I have only 512Kbps with my ISP.

So the max number of call that can be supported is 6, because of the FastEhternet.I use VPN (site-to-site) for the call tranfert to my remote CME.

1 - Is there any idea to improve the number of the call?

2 - How can I reduce the bandwitdh consumption, per call? Now it is 60Kbps per call. I wanna reduce it.

I already use VPN (group 2 for the isakmp policy) and autoQoS Voip.

Thanks :-)

Hall of Fame Super Gold

Re: rtp header compression on VPN

Hi,

Are you using g.711 ? That would be 87 kbps per call, not 60.

You can configure g.729 under the ephones, but you need to do that for all the ephones you are using site-site.

Community Member

Re: rtp header compression on VPN

Hi,

No I'm using g729r for the two dial-peer.

The calculation is with thi site : http://tools.cisco.com/Support/VBC/do/CodecCalc2.do

I'm using tunnel interface for the VPN.

Thks,

Hall of Fame Super Gold

Re: rtp header compression on VPN

Hi,

if g.729 is successfully negotiate (check on the phones pressing ? twice and look at info), your only option to reduce bandwidth would be to pass voice without VPN, directly on a internet interface with public address.

Community Member

Re: rtp header compression on VPN

Hi,

If I don't use VPN, there is no safety.

And how about fragmentation?

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