Technical data

78 Brocade ServerIron ADX Advanced Server Load Balancing Guide
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Content-aware cache switching
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How content-aware switching works
Content-aware switching (CSW) is the ServerIron ADX's ability to direct HTTP requests to a server, or
group of servers, using information in the text of a URL string. The ServerIron ADX examines the
contents of a URL string and makes a decision about where to send the packet based on selection
criteria in user-defined policies. If text in the URL string matches the selection criteria, the HTTP
request is sent to a server group specified in the policy.
NOTE
"URL string" is defined as the contents of the Request-URI part of the Request-Line in an HTTP
request message. This information usually consists of the absolute pathname (directory and
filename) of a resource; for example, /doc/ServerIron ADX/1199/url_switching.html.
The URL string can also be the input to a process running on a remote server; for example,
/quote.cgi?s=BRCD&d=1d.
The network location of the resource is specified in the Host header field in an HTTP request
message; for example, Host: www.brocade.com.
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).