Accurately Estimate Network Resource Utilization

By Tim McCreery  |  Posted 2008-12-23 Print this article Print

Step #3: Accurately estimate network resource utilization

Accurately estimate the network resource utilization for the proposed VOIP system. Unlike traditional land lines where users have the equivalent of dedicated switch ports, a VOIP system is usually placed on a shared medium. Converged networks are what everyone is trying to implement to save money. Be sure to consider the number of simultaneous calls that will occur. With that information in hand, you can easily calculate the aggregate bandwidth that will be needed to support all calls during peak calling periods.

By benchmarking the requirements for a single VOIP call, computing the aggregate call traffic and comparing these values with baselines of existing network activity, it will be simple to determine if VOIP will "fit" in your current network. If the numbers do not add up, you may need to consider architectural changes to your IT infrastructure.

Step #4: Select a codec with higher speech sampling rates

Select a codec with higher speech sampling rates. In general, the higher the speech sampling rate, the better the potential call quality (but at the expense of more bandwidth being consumed). Make tradeoffs carefully. For example, G.711 provides excellent quality. Data is delivered at 64K bps, and the codec imposes no compression delay.

Technically, G.711 delivers 8,000 bytes per second without compression so that full Nyquist-dictated samples are provided. However, if you are attempting to pack multiple phone calls over a narrow bandwidth circuit, you may need to accept slightly lower quality to use a codec that is less hungry for bandwidth.

Tim McCreery is President and CEO of WildPackets, Inc. Tim has over 25 years of experience in the networking industry. Tim co-founded WildPackets as AG Group in 1990. Tim's past positions include Founder and President of Kinetics, Founder and CEO of SilkStream Corporation, and VP of Marketing and Business Development at Excelan, Inc. Tim has also been on the board of other startups, including Clear Ink Corporation and Tut Systems. Tim is also President of the Board of Youth Homes, Inc., a non-profit agency serving at-risk foster care children in Contra Costa County, Calif. Tim graduated from the University of California, Berkeley with degrees in Mathematics, Computer Science and Psychology. Tim taught undergraduate Computer Science at U.C. Berkeley while obtaining a Master's degree in Electrical Engineering and Computer Sciences. He can be reached at

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