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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: OT? cRTP header compression
On Thu, 11 Apr 2002, Mathew Lodge wrote: > As well as increasing sample size (thereby increasing the payload:header > ratio), the other thing to try is turning on voice activity detection (VAD, > AKA silence suppression). For human conversation, this typically reduces > packet rates by around 60%, enabling you to squeeze more conversations onto > the link. It also has the side effect of reducing CPU utilization per call > on your Cisco voice gateways. Note that turning on VAD does decrease the > perceived voice quality a little, so whether it is worth it depends on > where you want to make the trade-off between cost and voice quality. I am not a big fan of VAD in my network, customers do not like the silence they get on the other end. As far as packet size, you want to use the smallest you can get away with. I use 9 or 21 ms of G.726 on my network, I know they are odd sizes, but we run our own version of CRTP directly over AAL5 so we want to fill the cells correctly. If you are looking for more info on VoIP/CRTP check out the following: http://www.robotics.net/papers/integratedvoice.html I also have a Excel took that will let you play see what CRTP, frame size, CODEC, link speed look like for VoATM, VoIP, and FoFR. http://www.robotics.net/clec/tools/index.html ><> Nathan Stratton CTO, Exario Networks, Inc. nathan at robotics.net nathan at exario.net http://www.robotics.net http://www.exario.net
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