Hi Antonio, Agreed with all the info you mention below, I am only talking about RTP vs cRTP usage on diff series, does anyone have info with the CPU uage vs the number of calls/sessions/DS0s sent accross the link that has header compression enabled? All the rest related to QoS, Link Fragmentation, packet size and so on has been covered. Thomas ----- Original Message ----- From: "Pena, Antonio" <Antonio_Pena@verestar.com> To: "'Thomas Kernen'" <tkernen@deckpoint.ch>; <nanog@merit.edu> Sent: Wednesday, April 10, 2002 11:55 PM Subject: RE: OT? cRTP header compression

Hello Thomas

I had some kind of experience doing cRTP over Cisco routers, we use

7204 & 7206 Routers on the IP Gateways and Cisco's 3600 and 5300 as VoIP gateways, as well we had a small setup using a Cisco 2611 router on

termination router.

The trick is change the VoIP payload size of each packet to reduce the packets per second in a half improving the performance over the routers, also we are using as Cisco recommends TCP & RTP headers compression over the circuits using only MLPPP encapsulation.

Also please note that using cRTP and Compression you have increased

Cisco the the

switching delay over the circuit and for that reason you may need also to have more processing power of the router.

Below you can see a Cisco site where you can check the recommendations for this setup and also based on that information I created a Bandwidth calculator on an excel sheet, if you want it, just drop me an email, I will send it you.

http://www.cisco.com/warp/public/788/voice-qos/voip-mlppp.html

http://www.cisco.com/warp/public/788/pkt-voice-general/bwidth_consume.ht ml

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/ fqos

_c/fqcprt6/qcfcrtp.htm

http://www.cisco.com/warp/public/105/compression-qos.html

Bye

Antonio J. Pena Manager, Network Engineering

( /_ _ _ __/_ _ |_/(-/ (-_) /(// Verestar, inc. 1901 Main street Santa Monica, CA, 90405 Phone(310)382-3300 Direct(310)382-3409 antonio_pena@verestar.com http://www.verestar.com

-----Original Message----- From: Thomas Kernen [mailto:tkernen@deckpoint.ch] Sent: Wednesday, April 10, 2002 1:11 PM To: nanog@merit.edu Subject: OT? cRTP header compression

I'm looking for real world experience related to deploying cRTP header compression on Cisco routers related to VoIP flows. We are trying to evalute what type of hardware (ie: CPU power since cRTP is CEF switched since 12.2x IIRC) is required to handle 96/192/384 VoIP calls over a single circuit (HDLC/PPP/FR). This is related to specific overseas circuits where the cost of the circuit is still very expensive vs the cost for the extra hardware to handle the header compression. I'm disregarding all QoS info at this stage.

Cheers Thomas