Technical data

ServerIron ADX Advanced Server Load Balancing Guide 69
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Content-aware cache switching
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The ServerIron ADX can examine both the URL string and Host header field when determining where
to send the HTTP request. Refer to RFC 1945 or RFC 2616 for more information on HTTP request
messages.
The selection criteria in a policy can be a string of characters starting from the beginning of the URL
string, the end of the URL string, or within any part of the URL string. For example, selection criteria
can be a URL string that starts with the text “/home”. In a TCS environment, when a client sends an
HTTP request that has a URL string beginning with the text “/home", the policy can direct that
request to a specific group of cache servers (or to another CSW policy for additional matching).
Basic example of content-aware cache switching
The diagram in Figure 19 illustrates a configuration that uses content-aware cache switching to
cache GIF files on one set of cache servers and different kinds of files on another set.
In this configuration, Cache Group 1 consists of three cache servers. CacheServer1 and
CacheServer2 are allocated to Server Group ID = 1, and CacheServer3 is allocated to Server Group
ID = 2. The ServerIron ADX has CSW policies in place that cause HTTP requests to be directed to
the cache servers as follows:
• HTTP requests containing URL strings that end with the text "gif" are sent to one of the cache
servers in Server Group ID = 1.
• If a URL string does not end with the text "gif", the HTTP request is sent to the cache server in
Server Group ID = 2.