irule to change pool based on state of another server or pool

Since iRules are triggered by incoming connections and not changes in a pool member's state, I don't see how this can be done by iRules.

 

 

-Al

Al is correct that changes elsewhere won't affect local iRule decisions, but I think we could take a bit of an outside-the-box approach to solve the problem:

I suppose you could define at each site a pool (not used for LB) that contains only the remote SMTP server, just for the purpose of monitoring its status. (You wouldn't need to know the status of the local SMTP server, I think, because if it's a silo, no traffic would come through the local scrubber VS from the dead SMTP server, right?)

You'd keep the existing local scrubber pool as the default pool, and create as you mention another global scrubber pool containing all the scrubbers from both sites.

Then in an iRule, use the LB::status command to check if the remote SMTP server is down, and choose the appropriate pool accordingly:

when RULE_INIT {
  set ::RmtSvrIP 192.168.1.1
  set ::RmtSvrPool RemoteSMTPServer
}
when CLIENT_ACCEPTED {
  if {([LB::status pool $::RmtSvrPool member $::RmtSvrIP 25] != "down") } {
     pool LocalScrubberPool
  } else {
     pool GlobalScrubberPool
  }
}

HTH

(I'd be interested to know if this works for you.)

/deb

Forgot to mention (in case it didn't jump right out at you) that you'd have to run an SMTP monitor/health check against the remote SMTP server to determine its status.

Thank you. I was concerned if this idea would work or not. I am going to try this in my dev environment and respond with results. You are correct that I dont need to know the status of the local SMTP server - only the one on the other site. The same applies for VIP configuration on the other site. I did catch the monitoring requirement as that is key to this approach, thanks for pointing it out though.

 

 

PM