Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Traffic Engineering


Currently, I have an ISP customers and they are planning to upgrade their backbone network in order for them to provide good quality of service for video conferencing application. At the moment, they have 3 E1 lines to Local

ISPs in Malaysia and planning to have 2 E1 connections to UUnet soon.

Anyway, is there any formula or rules that we engineer to work on in

order to decide how much bandwidth required for Video Conferencing Application? For

example, if I am planning to have 5000 subscribers users will be active at the same time, then how much bandwidth do I require in order to offer good video services? Anybody any idea? A lot of local

engineers keep on telling me that we can only guess for the bandwidth and there is no exact answer? Is that true? I really doubt it. Thanks for your advice

New Member

Re: Traffic Engineering


There is a document on H.323 traffic that can give you some ideas on the bandwidth required, see:

There is also another site that deals with Erlang tables and traffic models for VoIP, they have a calculator for IP telephone traffic:

Otherwise, the only solution I can think of is that you agree with the client/users what percentage of con-current calls they will accept/are prepared to pay for, and go with that to start with.

Hope this helps.


New Member

Re: Traffic Engineering

I think I can't access to this url and I think the site is down at the moment. Anyway, thanks for your information.

New Member

Re: Traffic Engineering

There are too many variables to answer your question in any meaningful fashion. Video conferencing is typically made up of 2 media streams - one voice/one video. Voice will typically use a codec such as G.723, G.728, G.711, G.722 etc... and consume anywhere from 8k to 120k of b/w. Video uses H.261/H.263 codecs ranging anywhere from 80k to 2MBps. Rule of thumb, add 15% IP overhead to any aggregate voice+video calculations you make per stream. "Quality" video is a subjective term but business users typically want 384K VC streams which produce 30fps operation and "near-TV" quality. Your number of 5000 users is again not helpful in traffic engineering. The more salient number is frequency of calls, desired call speed, and max number of concurrent users. You also need to consider feature sets such as multipoint control units and gateways to other protocols.

New Member

Re: Traffic Engineering

I conducted a video over IP test for bandwidth utilization at the enterprise level network. Four clients with H323 software dialed into a Radvision MCU and each client registered approximately 450Kbps. That was total usage per client as each way registered 225Kbps with T.120 collaboration. Each call was a 384Kbps. We calculated that eight users would utilize as much as 3.6Mbps on an Ethernet LAN. The same test over an ATM backbone would require as much as 530Kbps for a 384Kbps video call. The ATM video call would required that much bandwidth due to ATM overhead for QOS over VBR-rt.

CreatePlease login to create content