A/B Site Testing

Ronan,

probably the simplest solution is to create another pool which is union of ChannelA and ChannelB nodes. If you use round-robin loadbalancing method (which is the default) and you interleave A and B nodes in the new pool, you will (in average) get 50:50 distribution of connections to A and B nodes via the new pool.

Here is how the configuration may look like:

pool ChannelA {
   member 10.1.1.1:80
   member 10.1.1.2:80
}
pool ChannelB {
   member 10.1.2.1:80
   member 10.1.2.2:80
}
pool ChannelAB {
   member 10.1.1.1:80
   member 10.1.2.1:80
   member 10.1.1.2:80
   member 10.1.2.2:80
}
rule distributor {
   if (exists http_cookie("cookietest") and http_cookie("cookietest") contains "ChannelA") {
      log "ChannelA used"
      use pool ChannelA
   }
   else {
   if (exists http_cookie("cookietest") and http_cookie("cookietest") contains "ChannelB") {
      log "ChannelB used"
      use pool ChannelB
   }
   else {
      log "Cookie NotFound"
      use pool ChannelAB
   }
}

If you have other preferences how to distribute connections to servers, you may want to use the direct node selection feature in the ChannelAB pool. See BIG-IP Reference Guide for details.