Save bandwidth: Use Frame Relay for VoIP
Tom Lancaster
Why not use Frame Relay for your VoIP network? Here's one good reason to do so. If you have other ideas of how to save bandwidth in VoIP applications, why not send them in?
Although Frame Relay networks have always been an economical option for Voice over IP and data connectivity, many companies choose dedicated or point-to-point circuits instead on the premise that the larger, guaranteed bandwidth will result in better voice quality. Generally speaking, this is a reasonable assumption.
However, if you perform a quick analysis of the traffic on your network, you will probably find that the packets traveling one direction are primarily small requests, while the packets traveling the other direction are primarily larger responses, filled with the requested data. As a result, the voice quality may be relatively good in one direction and relatively poor in the other. So if you set the Committed Information Rate (CIR) large enough to handle the heavily utilized direction, you?re paying for a lot of unnecessary bandwidth in the other direction. And if you set the CIR appropriately for the underutilized direction, then too much traffic in opposite direction will be marked Discard Eligible and likely be dropped. Hopefully, this wouldn?t include your voice traffic.
One advantage Frame Relay has over dedicated, end-to-end circuits is that the Permanent Virtual Circuits (PVCs) are actually asymetrical. Although most companies order PVCs with the same CIR in both directions, it is possible to purchase a higher CIR in one direction and a lower CIR in the other direction. For instance, the PVC from point A to point B may be a 768 Kbps CIR, while the same PVC only has a 128 Kbps CIR from point B to point A.
So, if you have a network where 80% or more of your traffic flows in one direction, why pay for the same service in both directions?
Thomas Alexander Lancaster IV is a consultant and author with over ten years experience in the networking industry, focused on Internet infrastructure.
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Related Book
Frame Relay: Technology and Practice
Author : Jeff Buckwalter
Publisher : Addison Wesley
Published : Dec 1999
Summary :
Frame Relay: Technology and Practice is the most comprehensive, current, and practical handbook available for understanding and deploying frame relay. Gathering information from many different sources, this book provides essential facts and techniques in one convenient volume. It explains frame relay technology in understandable terms, interprets frame relay standards, and discusses vital deployment issues.
