Five times, 10 times, 20 times or more: The performance benefits from application acceleration are real - provided you understand what the technology can and can't do for your network. Here are best practices for deploying application-acceleration devices.

1. Define your goals

There's no one way to make an application go faster. For some users, reducing WAN bandwidth consumption and cutting monthly circuit costs may be the key goals. For others, the key goal will be speeding up bulk-data transfer. For others, improving the response time of interactive applications is most important.

Deciding where to deploy application acceleration also is a consideration. Pairs of acceleration devices work in the datacentre, deployed on both ends of a WAN link; increasingly, they also are deployed as client software on telecommuters' or road warriors' machines. Identifying the biggest bottlenecks in your network will help you decide which parts of your network can benefit most.

It's also worth considering whether application acceleration can complement other enterprise IT initiatives. For example, many organisations have server-consolidation plans underway and are moving remote servers into centralised data centres. Symmetrical WAN-link application-acceleration devices can reduce response time and WAN bandwidth use, giving remote users LAN-like performance. In a similar vein, application acceleration may help enterprise VoIP or video roll-outs by prioritising key flows and keeping latency and jitter low.

2. Classify before you accelerate

Many acceleration vendors recommend deploying their products initially in pass-through mode, meaning that devices can see and classify traffic but not accelerate it. This can be an eye-opening experience.

The adage "you can't manage what you can't see" applies here. It's fairly common for enterprises to deploy acceleration devices to improve the performance of two to three key protocols - only to discover their network carries five or six other types of traffic that also would benefit from acceleration. On the downside, it's also all too common for enterprises to find applications they didn't realise existed.

The reporting tools of acceleration devices can help. Most devices show which applications are most common in the LAN and WAN, and many present the data in pie charts or graphs that can be understood easily by non-technical management. Many devices also report on LAN and WAN bandwidth consumption per application - or per flow.

Understanding existing traffic patterns is critical before acceleration is enabled. Obtaining a baseline is a mandatory first step in measuring performance improvements from application acceleration.

For products that do some form of caching, a corollary to traffic classification is understanding the size of the data set. Many acceleration devices have object or byte caches or both, often with terabytes of storage capacity. Caching can deliver huge performance benefits, provided the data gets served from a cache. If you regularly move 3TB of repetitive data between sites, but your acceleration devices have only 1TB of cache capacity, caching obviously is of only limited benefit.

Even without deploying acceleration devices, it's still possible (and highly recommended) to measure application performance. Cisco NetFlow and similar tools, or the IETF's open sFlow standard, are implemented widely on routers, switches and firewalls, and many network management systems also classify application types.