F5 GTM+LTM for Data Center Backup

This is a fundamental function for GTM.

In terms of architecture, the GTM will talk to the LTMs in both datacentres to check the state of the virtual servers. Within GTM, these virtual servers are setup as pools which are assigned to a Wide IP and can be configured in different loadbalancing algorithms - active/standby ( Global Availability ) , Round Robin, closest geographical datacentre etc.

When a user wants to access an application, it makes a DNS request to the GTM system which looks at which pools are up or down and makes a loadbalancing decision. It then sends back the DNS response pointing to the IP address in the relevant datacentre.