Technical data

ServerIron ADX Advanced Server Load Balancing Guide 81

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Cache persistence using URL hashing

1. Get http://login.yahoo.com/config/mail?.src=ym HTTP 1.1

2. Get /config/mail?.src=ym

Host: login.brocade.com

The following table demonstrates which part of the string would be used for hashing either of the

prior examples depending the method selected with the csw-hash url command.

Cache persistence using hashing on a portion of the URL

You can be more specific about the information in the URL that you want to determine traffic

distribution for by parsing the URL string. This is done by specifying a “pattern-string” and parsing

the URL string using a delimiter or an length limit. You can either parse the entire URL string or only

the “host-only” portion of the string.

• the hash-persist url search-url command is used where the entire URL is being parsed.

• the hash-persist url search-host command is used where the host portion of the URL is being

parsed.

Parsing the entire URL

Parsing the entire URL string allows you to select a portion of a URL to perform hashing on. The URL

is searched to find a pattern string. This pattern string is combined with a configured offset value to

identify a starting point. From this starting point in the URL, a string that will be used for hashing is

derived by a method that is specified by the options you select for the hash-persist url search-url

command. These options are described in the following.

Parsing using the “pattern string” only – With this option, the ServerIron ADX begins at the starting

point in the URL and includes all of the characters up-to the end of the URL to form the string used

for hashing.

Search URL string by starting at a “pattern string” and ending at a delimiter – With this option, the

ServerIron ADX begins at the starting point in the URL and includes all of the characters up-to a

specified delimiter character in the URL to form the string used for hashing.

Search URL string by starting at a “pattern string” and continuing for a specified length – With this

option, the ServerIron ADX begins at the starting point in the URL and includes the number of

characters specified to form the string used for hashing.

Parsing using the “pattern string” only

The following example identifies a pattern string to perform hashing on with an offset of “0”.