Surf's Up

Smart Caching

OptiView's caching algorithms evaluate content against LMT (last modified time) to ensure that content is expired only when necessary. If no cache-control headers are present or the LMT is always "now" (content that rarely changes is set to expire immediately), the device will ignore the directives and direct the client to use objects in the browser cache, if they exist, or will serve the object from its own cache if the client has not accessed the object already. If the server sets an expiration via a cache-control header, however, that expiration is always respected by the device.

SiteCelerate can be set up to update its software automatically. The default is set to check for updates every hour or an administrator can initiate updates. Objects are cached in a compressed state, making the most of SiteCelerate's internal storage, and will be decompressed for clients that cannot receive compressed data.

SiteCelerate uses SNMP for monitoring and statistics gathering. And its customized Linux OS uses MRTG (Multi Router Traffic Grapher), which is a GPL (GNU Public License) solution for monitoring and graphing network traffic via SNMP. Access logs also are available in raw-text format.Manipulating Content

I test drove a beta version of SiteCelerate in our Real-World Labs® in Green Bay, Wis. You must use a console session to perform the initial network configuration, then use the Web-based GUI for subsequent configuration. Little setup is required for basic functionality, and within minutes I was able to use the device as a manual proxy.

URL redirection lets you manipulate the URLs sent via the proxy and direct them to alternative content or servers. You could easily mess with your co-workers by setting the device to translate www.google.com to www.yahoo.com.

More practically, you can use the URL redirection to force the device to pull images from one server while pulling content from another, letting you design a more efficient Web site and take full advantage of HTTP 1.1 without purchasing an expensive load-balancing solution.

I configured SiteCelerate to fulfill requests from two internal servers--an Apache server on RH 7.3 for images and a Spirent Communications WebReflector (formerly from Caw Networks, which was acquired by Spirent) for static content.Using Spirent's WebAvalanche to simulate both clients and a server for an 8-KB image and 32-KB text file, my setup achieved an average of 1,150 gets per second and throughput of approximately 40 MB per second. That was quite an improvement over the average 800 gets per second served by NetCelerate in my previous test.

I verified the performance of the device using ApacheBench, then requested a 32-KB file from the device. It was able to process 1,200 gets per second and reduce the size of the document to 704 bytes from 32 KB. SiteCelerate achieves this reduction by using standard compression technology for both text and images and by stripping out comments in HTML to reduce the amount of data being transferred.

There are four steps to configuring the device as a reverse proxy cache: check the box "WCCP active," specify the router, specify the port to use on SiteCelerate and specify the device's internal address. Router configuration is dependent, of course, on the router you are using.

I used a Cisco Catalyst 6500, which was simple to configure. One caveat: SiteCelerate requires the use of WCCP version 1, not version 2. As soon as I finished configuring the device, it began to provide reverse-proxy caching and performed as well as it did when I used it as an explicit proxy.Recommended Uses

SiteCelerate is a great way to go for a smaller business that wants to ensure that customers are getting an "accelerated experience," and its ability to double as an internal proxy cache means both functions are provided at a single, affordable price.

For high-volume sites and enterprise-class customers, however, the lower processing power and lack of integration with authentication mechanisms make the product an unlikely choice for the double task. But keep an eye on the product line: OptiView says it has plans to move into the more demanding corporate-class space.

Technology editor Lori MacVittie has been a software developer, a network administrator and a member of the technical architecture team for a global transportation and logistics organization. Write to her at [email protected].