Immediate reset when all nodes for a VS are unavailable

The reason you're seeing a completed TCP handshake is due to the new Full-Proxy architecture of BIG-IP version 9.x. This architecture uses seperate connections to the client and server to transfer information, so the TCP handshake you're seeing on the client side is with the BIG-IP, not with the end server.

As far as an immediate disconnect, I think the closest you're going to see in a rule is if you use the LB_FAILED command, and immediately send the desired response to the client, and terminate the rule.

THis would look something like :

when LB_FAILED {
  TCP::respond $myResponseData
  TCP::close
  return
}

This is, of course, just a general example, and not tested.

-Colin