Forum Discussion

Andrew_Wysocki_'s avatar
Andrew_Wysocki_
Icon for Nimbostratus rankNimbostratus
Apr 15, 2016

GTM iRule to set the pool based on which GTM is responding to query

I've been asked that when a DNS request comes into a GTM, that it responds with the GTM pool which is local to that GTM site if it's available. The setup is as follows, 2 DC's, a GTM at each, synced ...
application delivery
BIG-IP DNS
iRules
Andy_McGrath's avatar
Andy_McGrath
Icon for Cumulonimbus rankCumulonimbus
Apr 15, 2016

Hi think I understand what you are trying to do however can I ask how your DNS is setup to send traffic to your GTMs?

 

Reason I ask is in most setups your GTMs will be Name Server (NS) records within some DNS and so requests from client will alternate between the GTMs and so if your iRule works as expected a client session (depending on the application) could flip between data centres.

 

I would recommend looking at GTM Topology features which would allow you to set the DC based on the source IP/Subnet. i.e. Client sends query to local DNS which sends query to one of the GTMs, the GTM looks up the local DNS IP and selects the DC, pool or virtual server from the topology policies.