Irule expaination

Gist:

You should be having multiple pools that start with "web_8080_{some-value-here}". Traffic is sent to the pool identified by "web_8080_{some-value-here}" if there are available members and if not, to the pool: web_proxy

A bit more detail:

[substr [HTTP::uri] 0 "?"] - if you have a string like this in the URI:

/index.jsp?user=test&login=check

-

/index.jsp

will be the answer and this will be subjected to crc32 and then the remainder of the value when divided by 3 is used as "key" which is then used as "{some-value-here}" in the pool name as noted in the 1st line of this comment.

when HTTP_REQUEST { 
set pool_nm "web_8080_" 
set key [expr {[crc32 [substr [HTTP::uri] 0 "?"]] % 3}] 
append pool_nm $key 
if { [active_members "$pool_nm"] } { 
pool "$pool_nm" 
} else { pool web_proxy 
} 
}