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SSHSSH_97332's avatar
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Feb 12, 2012

GTM Question

For GTM to Work , whay does it need 2 GTM boxes ? i know about LTM & LC can someone brief to me GTM functions ?







3 Replies

  • You don’t need 2 boxes for GTM to work. But it depends on the architecture, and how it was designed. You can have GTMs in failover for High Availability (active/standby) in a DC. You can also have a GTM per datacentre running in a sync group.



    But you can have a single GTM box, offsite from your datacentres, that can do the GSLB between your datacentres.


  • GTM is F5's GSLB (Global Server Load Balancing) solution, this enables site redundancy using DNS. In a simplified environment with 2 sites you would require a single GTM device on each site, you could not perform this with a single box on one site as this would not achieve the site redundancy aim if the site with the GTM was to fail.



    The GTM's on each site poll the other GTM (using iQuery: 4353) and also the other LTM's (or other load balancers), and servers on both sites, if there are communication issues then the GTM will mark the service as down and will not direct DNS queries to that service.



    Link Controller (LC) is a cut down version of GTM that does not allow the inbound GTM functions but allows for (outbound) link load balancing, this is also included in the full GTM product.