Broadband Testing, an independent laboratory specializing in network performance, recently ran a ZXTM appliance through a range of rigorous tests to find the true limits of its performance. Highlights include full content inspection and rewriting at a rate of 640 Mbit/s, and XML inspection and translation (XSLT) at over 550 Mbit/s.

The full test report is published on www.zeus.com.

Overview

ZXTM really shows its strengths when performing complex layer-7 manipulation, such as decrypting, inspecting or rewriting requests and responses. The BroadBand testing exercise was intended to test ZXTM's scalability and to measure some typical layer-7 tasks.

Layer-7 Content Rewriting

A common task is to rewrite parts of a web page - perhaps a URL has changed, but the web site content has not been completely audited and corrected.

In this test, Zeus prepared a sample web page containing 4 instances of the string 'media.example.com'. ZXTM was configured to rewrite web pages on the fly, changing all instances of 'media.example.com' to 'images.example.org'. In the test, the length of the response was changed, so a simple in-place replace could not be used.

The following TrafficScript rule was used to effect the transformation:

$body = http.getResponseBody();
$new = "";

while( ( $i = string.find( $body, "media.example.com" ) ) != -1 ) {
   $new = string.append( $new, string.substring( $body, 0, $i-1 ), "images.example.org" );
   $body = string.skip( $body, $i+17 );
}
$new = $new . $body;

http.setResponseBody( $new );

A single ZXTM 5000 appliance (Linux on a dual AMD Opteron 246 server) could sustain almost 8000 rewrites per second; including the HTTP headers, this equates to 640 Mbit/s of content inspection and rewriting.

XML inspection and XSLT translation

In this test, BroadBand testing simulated Google's "I'm Feeling Lucky" feature. The testing kit requested a 10K XML document from a back-end server via ZXTM. The document contained 10 results from Google's SOAP-based search API.

ZXTM ran an XSLT transformation on the document. This transformation extracted the first search result, and formatted it up as a simple HTML document. ZXTM then corrected the content-type of the response and returned the HTML document to the client.

The following TrafficScript rule and the imfeelinglucky.xsl stylesheet was used to effect the transformation:

$response = http.getResponseBody();

$xsl = resource.get( "imfeelinglucky.xsl" );
$results = xml.xslt.transform( $response, $xsl );

http.setResponseHeader( "Content-Type", "text/html" );
http.setResponseBody( $results );

A single ZXTM 5000 appliance (Linux on a dual AMD Opteron 246 server) could sustain 6800 rewrites per second; including the HTTP headers, this equates to over 550 Mbit/s of XML content inspection and rewriting.

Performance

During the testing exercise, Broadband testing examined several other dual Opteron-based platforms. All tests were CPU-bound, and performance was found to scale linearly with processor speed (GHz):

Source: www.amd.com.

Owen Garrett [Zeus Dev Team] 29 November 2005