Moving traffic from VIP to VIP

Hi Sekharchandra,

 

the following iRule is hopefully doing what you try to accomplish. Please replace the relevant values for hostnames to redirect to and the ratio values.

 

Turn off logging, if it works as expected. Please keep in mind, that there is no default pools needs to be associated with this iRule and there is no healthchecking considered.

 

No need to modify anything in the context of HTTP_REQUEST.

 

when RULE_INIT {
     set servername to use for responses (default will be "BIGip"), turned off with "noserver" switch in HTTP::respond
    set static::srvname "ServerLB"
     set redirect code (301=moved permanently, 302=moved temporarily)
    set static::statcode 301
     set server ratio values
    set static::ratioA 1
    set static::ratioB 9
     set server hostnames
    set static::hostA "www.serverA.bit"
    set static::hostB "www.serverB.bit"
     activate logging (0=disabled, 1=enabled)
    set static::debugRatioLb 1
}

when HTTP_REQUEST {
    if { [expr {[table incr req_counter]%[expr {$static::ratioA+$static::ratioB}]}] < $static::ratioA } {
         values from 0 to less than ratioA will be directed to serverA
        if { $static::debugRatioLb > 0 } {
            log local0. "total counter: <[table lookup req_counter]>; modulo <[expr {[table lookup req_counter]%[expr {$static::ratioA+$static::ratioB}]}]> match ratio <$static::ratioA>"
        }
        HTTP::respond $static::statcode noserver server $static::srvname Location http://$static::hostA[HTTP::uri]
        return
    } else {
         values greater than ratioA will be directed to serverB
        if { $static::debugRatioLb > 0 } {
            log local0. "total counter: <[table lookup req_counter]>; modulo <[expr {[table lookup req_counter]%[expr {$static::ratioA+$static::ratioB}]}]> match ratio <$static::ratioB>"
        }
        HTTP::respond $static::statcode noserver server $static::srvname Location http://$static::hostB[HTTP::uri]
        return
    }
}

The iRule is designed for two target servers only but can be easily enhanced.

 

Thanks, Stephan