Included in Local Traffic Managers Universal Inspection Engine (UIE) is a set of functions that you can specify within BIG-IP system iRules to direct traffic in more granular ways. Using these iRule functions, you can write expressions that direct traffic based on content data, or direct traffic to a specific member of a pool.
Universal persistence takes this iRules feature one step further, by allowing you to use the iRule persist uie command to implement persistence for sessions based on content data, or based on connections to a specific member of a pool. Universal persistence does this by defining some sequence of bytes to use as a session identifier.
To use iRule expressions for persistence, a universal persistence profile includes a setting that specifies the name of the iRule containing the expression.

rule my_persist_irule {
when HTTP_REQUEST { persist uie [HTTP::header myheader] }
}

Universal persistence profile