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Jimbo_01_43689's avatar
Jimbo_01_43689
Icon for Nimbostratus rankNimbostratus
Jan 24, 2013

GTM failover between data centers

Hi,

 

I need some help understanding how F5 GTM fails over between data centers in the event of a failed data center scenario. If we have one single GTM appliance in each data center A & B and DC A fails how does clients get redirected to DC B? The GTM appliances would lose Iquery communication, does GTM in DC B dynamically update internet root DNS servers with new ip address for its DNS domain so once clients Local DNS server cache expires, its redirected to DC B?

 

 

Thanks for any advise.

 

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  • Leo_D_53884's avatar
    Leo_D_53884
    Icon for Nimbostratus rankNimbostratus
    Jan 25, 2013

    Jimbo,

     

    There is a lot of area to cover with this question and the answers depend on your topology. Are your hosting all DNS on your GTMs, active-active or active-passive datacenters, etc.? I allowed iQuery between my GTMs via the Internet as well as internal links. A good start would be the link below.

     

     

    http://support.f5.com/kb/en-us/products/big-ip_gtm/manuals/product/gtm-implementations-11-2-0.html

     

     

    leo

     

     

  • Jimbo_01_43689's avatar
    Jimbo_01_43689
    Icon for Nimbostratus rankNimbostratus
    Jan 29, 2013
    Hi Leo,

     

     

    I was planning to run DNS server on the GTMs, hosting the authoritative domain. Trying to work out how the ISP DNS servers would load traffic between the two GTMs? and how it would behave in a DC failure? We don't have Data center interconnects between our DCs, only connected via the WAN. I assume running IQuery over the internal WAN & internet is a common topology?
  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    Jan 30, 2013
    GTM (should if implemented correctly) fails over in exactly the same way any other dns service (eg bind) fails over...

     

     

    All your GTM VS's are listed as NS records for the domain (or traffic passes through them as transparent inline, but that implies limitations so i never deploy like that). So when resolution is required for the delegated domain, they get queried... If one fails, the other(s) keep responding... As far as the outside world is concerned they're just another dns server. The smarts is in their montoring and decision making on which ips to serve.

     

     

    H