How to sniff node down

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The LB::status section would evaluate a little differently.

Exerpt from Click here - http://tech.f5.com/home/bigip-next/manuals/bigip9_2/bigip9_2config/BIG_IP9_2ConfigGuide-14-1.htmlwp1200312

iRule command

LB::status

LB::status node

LB::status pool member

Description

Returns the status of a node. Possible values are up, down, session_enabled, and session_disabled. If you supply no arguments, returns the status of the currently-selected node

So you'd have something like:

when LB_FAILED {
  if { [LB::status pool  member  ] eq "down" } {
    log "Server $ip $port down!"
  }
}

-Colin