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George_32239's avatar
George_32239
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Jan 04, 2013

GTMs in two DC's with apps in one DC got that !

Hello All,

 

OK, I will try keep this simple !

 

We have two data centres, A and B (original I know). In data centre A we have the application servers but not in data centre B. There is a link between data centre A and data Centre B.

 

The desired result id that when someone on the Internet types app1.domain.com irt arrives at our ISP as the Auth Name servers for domain.com. In that zone file i have a delegated zone ceated and it has NS records for a GTM in data centre A and for the one in data centre B which both have seperate IP space.

 

As long as data centre A is alive then that is fine both GTMs will respond with a public IP that will direct the user to the IP space and therefore the app in data centre A.

 

If the internet link at data centre A blows up, I want the GTM in data centre B to respond with a public IP address that well direct users to data centre B public IP address and then it will use the cross data centre link to get to the hosted app.

 

Can this be automated; I think I can put a manual process in place, basically ceatting two pools on each GTM and enabling the pool for data centre A so it responds with the correct public IP and having another pool with a public IP address of data centre B in a disabled state. If the internet link for data centre A blows up, i disable that pool and enable the the pool that refers to data centre B so the next DNS request comes in and the user is given a public IP that resolves to the IP space in data centre B and we can connect across our data centre link to the application server in data centre A

 

Is there a way of automating this somehow, does the above even sound like a plan

 

All users are country specific and can potentially come in from absolutely anywhwre from an ISP point of view so not sure what my options are in determining where they come from and if that would even help.

 

Thanks for taking a look

 

George

 

config
design

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  • Chris_Miller's avatar
    Chris_Miller
    Icon for Altostratus rankAltostratus
    Jan 06, 2013
    To confirm, you'd like data center A to be the only IP handed out so long as DC A is up? If DC A goes down, DC B should be used. Both DCs send traffic to the same servers which are located in DC A?

     

     

    Are there app resources in DC B? Basically, what do you want to happen if the app disappears from DC A?
  • George_32239's avatar
    George_32239
    Icon for Nimbostratus rankNimbostratus
    Jan 08, 2013
    Hi Chris,

     

     

    Sort of, so we have a GTM in DC A and one in DC B, people out on the Internet ask for myapp1.doamnin.com. This request for name resolution could end up at the GTM in either DC A or DC B, in this case I want both GTM's to hand back a public IP address that says myapp1.domain.com = an IP address that sits in the DC A public range. No, lets say that myapp1.domain.com is still alive but we have lost something in the infrastructure of DC A lets say the outer firewall, so no requests are ever going to make it into DC A, I am assuming that public DNS servers will say I can't connect to the GTM in DC A so all DNS requests end up at the GTM in DC B, so the DNS request arrives at DC B, instead of it handing out the public IP of the myapp1.domain.com which means the request would go back out and it try and get in via DC A, I want it to hand back a public IP that is hosted in DC B, so the request comes in, the user gets given a public IP that comes back into DC B and then when the request comes back in we send it across a DC link

     

     

    If the myapp1.domain.com application is itself dead, then tough the will get a page can not be displayed howeever they come in

     

     

    Hope that makes a little more sense and thanks again for taking a look

     

     

    George