Thank you very much Aaron.
But in my enviroment, the 6 characters string is the identifier.
http://test.big-ip.com/install/123456/whateverxxxxxx
http://test.big-ip.com/scripts/456788/whateverxxxxx
It is as Mr. Chris Miller said, "if the URI contains "123456," go to server 1 and if it contains "456788," goes to server 2"
So I want to know how i can "grep" the 6 characters string from the url and then set it as "session_id" and then "persist" the connection.
I don't have any idea for the iRule Syntax for doing that, so please advise me. Thanks a lot~