GTM iRule. Is this possible?

Believe me when I tell you I was not keen on even proposing the question. But the customer wanted to know so I did it.

 

 

The problem is this. The customer initially insisted on a purely dynamic global load balancing system. Unfortunately, we later found out that there was little control over LDNS servers and many were behind firewalls and not queryable. They also do not have a clear idea as to where the LDNS servers are so creating a map is a monumental task. The end result was, as you pointed out, when RTT fails it went to RR and was sending people across the globe as opposed to their local node.

 

 

The customer didnt want to throw RTT away and asked if there was a way we could still use it. The only way I could think of was to create a topology for those we knew about and create an RTT pool for the rest. The only way to ensure that people were not sent to another continent was to see if there was an RTT for at least one non-US continental node and one US node and pick the shorter of the two. In the event there is no good RTT send it to the US since that is as 'central' as we would get.

 

 

Sadly, this is impossible in an iRule. We have basically settled on topology for pool LB where non-documented LDNS servers always get sent to the US.

 

 

Thanks for responding. You have actually given me the third party confirmation I was wanted to justify my decision.

 

 

A.J.