Remote Access Response Time Blues
by Robin Layland
Published June 2005; Posted August 2005

Abstract:

One of the big complaints from remote sites is always response time. Users constantly ask network managers to improve response time, to make it more like headquarters. The traditional remedy, “throw bandwidth at it,” works in many cases. Doubling the speed of the line does reduce the amount of time it takes to transmit the packets and is generally the best solution when the link is running at a high utilization.

But what is a network manager to do when link utilization is not the problem, and the remote site users are still unhappy with their response times? If the users are experiencing slow response time and the link utilization is low—under 40 percent—then adding more bandwidth will only marginally improve their response time. Plus, throwing bandwidth at the problem every time someone complains is expensive.

Technology, in the form of application accelerators, can help improve response time even when there is no crisis. Application acceleration helps by addressing non-bandwidth-congestion problems and by taking action to speed up the entire process.

The first wave of application accelerators to hit the market was called WAN optimizers. They compressed the data and manipulated TCP flow control parameters to improve throughput and response time. When they first appeared, the main marketing thrust was getting more out of the link and delaying upgrades. These early features are still important, but the emphasis is now on improving response time.

Application accelerators are the next wave of optimizers. They combine solutions from the first wave with innovative methods. WAN optimization vendors such as Packeteer, Expand, Peribit (recently acquired by Juniper Networks) and Riverbed bring their TCP expertise and improved compression techniques, along with new techniques aimed at file servers.

Application acceleration is a fast-moving area in which we can expect both technical improvements and more attention from the market. The only constant is that accelerators will improve and become more important to enterprises in the future and will comprise a standard part of remote site equipment.

About the author:

Robin Layland is president of Layland Consulting, a firm that specializes in network architecture and new technology. He has more than 25 years’ experience in enterprise networking, including technical and management positions at American Express and Travelers.

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