Early products handle traffic well, but need some polish

New Web front-end devices from Array Networks, NetScaler and Redline Networks each offer valuable techniques for dealing with growing traffic and security concerns. But while they can help improve site performance, we found plenty of rough edges.

In this round of testing, we focused on basic features including TCP offload, caching and compression, as well as newer features such as URL rewriting and content balancing. We plan to test these boxes again later this year for pure performance.

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New Web front-end devices from Array Networks, NetScaler and Redline Networks each offer valuable techniques for dealing with growing traffic and security concerns. But while they can help improve site performance, we found plenty of rough edges.

In this round of testing, we focused on basic features including TCP offload, caching and compression, as well as newer features such as URL rewriting and content balancing. We plan to test these boxes again later this year for pure performance.

Our Clear Choice award goes to the Redline E|X 3250, which excelled in our compression and TCP offload tests, and addressed important compatibility details. Additionally, Redline's powerful - albeit complex - OverDrive technology allows for highly customizable rewriting of inbound and outbound data, which can be used to improve security, make sites more adaptable to changes, and even improve performance with cache control.

The Array TM offers strong caching at a decent price and provides a layered approach to its other features that lets you add them as needed.

The NetScaler 9950 Application Switch is very focused on the needs of extremely high traffic sites with features like surge protection and priority queuing. However, it lacks any significant amount of URL rewriting features and had some issues with compression.

Redline: Strong Web delivery features

The Redline E|X was built for Web acceleration and is concentrated on realistic details - such as browser compatibility - that might be encountered with a public-facing Web site.

Installation and initial configuration is similar to that of the other devices tested: You set up basic network configuration via a serial connection and then perform further configuration via a Web interface or a Secure Shell connection.

While Redline provides a clean Web interface that offers some nice monitoring statistics, many features cannot be addressed via the Web interface. It covers basic network and cluster configuration, but ultimately you have to access the command line to tap into the more advanced features such as setting compression details or enabling caching features.

From the load-balancing perspective, Redline's default load-balancing method is that new requests go to the back-end server with the fewest outstanding HTTP requests. The company argues that looking at lower-level TCP-based metrics for load balancing is not effective. Redline engineers point out that by focusing on HTTP requests, literally every request made is considered a health check for the Web server. Our take is that while Layer 7-oriented load balancing and health checks might seem unfamiliar to some network administrators, they make perfect sense at least for Web-based applications.

Like the other products tested, the Redline unit offers TCP connection buffering and management as well as SSL  offload and acceleration. However, one area in which the Redline unit really shines is in HTTP compression. The Redline E|X was very aware of edge case issues with browser support for compression, and even opted to use deflate over standard Gzip compression for improved compatibility with browsers, given that some browsers have bugs that only occur with Gzipped content.

Redline provides more control over the degree of compression you can use than the other devices tested, even if you have to use command-line interface in this case.

In our compression tests (See How we did it ), we obtained the lowest overall delivery size (46,273 bytes for a 36.64% savings) of the units tested using a real-world example of the BBC's home page (original size 73,031 bytes). With some tuning, the device also aced our pre-built tests that addressed various mixtures of HTML, Cascading Style Sheets (CSS), JavaScript and images.

One compression annoyance is that the Redline unit inserts a somewhat excessive "advertising" header (so if you do a network trace you see a "powered by Redline'' tag) in every response, which skewed its results in the unit tests until we turned off the headers.

Redline OverDrive's AppRule language lets an administrator write powerful rules to filter and rewrite HTTP requests and responses. For example, a rule can be added to redirect requests for particular file types to a certain server, clean URL requests to make them user-friendly, and drop requests that contain certain known worm or attack signatures. The language is so flexible it can be used to add or remove headers at will, and even rewrite textual content in the body of responses on the fly. We were very impressed with this feature when we applied a rule to change the name of one company to another in a set of test HTML files.

OverDrive was frustrating at times. The language is terse and not always intuitive. Furthermore, it can be quite a chore to add AppRules by sending a file via trivial FTP to the unit or copy and pasting them into a file and then using command line to parse them. Redline should add rule support to the Web interface and provide a client-side tool to assist in creating valid rule files.

Redline's new "3G" caching feature lets developers create a cache on the unit and write AppRules to hold content in the cache depending on file extension, response code or whatever metric seems appropriate. Once the object is cached, future requests for it will be serviced by the Redline box, thereby freeing the origin server from the request.

Redline's approach to caching is not the automatic cache mechanism that the other two tested products provide. You must define rules to add files to the cache and understand when to invalidate them manually. This power can be dangerous if you aren't aware of application and browser cache policies. For example, we found that the unit happily sent the Firefox browser content even though the browser sent cache control headers indicating it wanted fresh copies.

The Redline E|X is clearly designed from the HTTP layer downwards. The product excels in HTTP compression, application-level redirection and balancing, and request and response rewriting. The 3G caching feature does not live up to its fancy name (implying it's seasoned code), although it can be useful if properly employed.