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Piotr_Lewandows's avatar
Piotr_Lewandows
Icon for Altostratus rankAltostratus
Jun 09, 2017

GTM and Topology

Hi,

 

I am quite new to DNS/GTM stuff so I had no chance yet to dig into how Topology LB works and what can be done.

 

Wonder if such configuration is possible:

 

Setup:

 

  • Two DC - DC1 and DR1
  • LDNS in each DC sending request to GTM (LDNS_DC1, LDNS_DR1)
  • Servers in each DC - defined as Generic Host
  • GTM serwing one Wide IP pointing to Servers in both DC

I would like to achieve this result:

 

When LDNS_DC1 sends request logic is:

 

  • If there is any Srv active in DC1 return IP of any (based on RR)
  • If there is no active Srv in DC1 return IP of any active Srv in DR1 (based on RR)

When LDNS_DR1 sends request logic is:

 

  • If there is any Srv active in DR1 return IP of any (based on RR)
  • If there is no active Srv in DR1 return IP of any active Srv in DC1 (based on RR)

So depending on which LDNS issued request logic is switched around.

 

Is that possible without iRule using just LB available at Wide IP and Pool level?

 

Side question: Which LB methods will work at all for Generic Host? I guess in this case all is based on analyzing communication between LDNS and GTM (no data that is provided when BIG-IP type of server is used)

 

application delivery
BIG-IP
BIG-IP DNS
devops
dr
generic host
lb method
topology

1 Reply

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  • cjunior's avatar
    cjunior
    Icon for Nacreous rankNacreous
    Jun 09, 2017

    Hello Piotr, As your requests will come from the LDNS, maybe the way bellow, solves that issue:

     

    GTM Server/VS:

     

    server_DC1/vs_name (with some monitor)

     

    server_DR1/vs_name (with some monitor)

     

    GTM Pool:

     

    pool_to_DC1_vs

     

    LB preferred: Global Availability

     

    Order 0: server_DC1/vs_name

     

    Order 1: server_DR1/vs_name

     

    pool_to_DR1_vs

     

    LB preferred: Global Availability

     

    Order 0: server_DR1/vs_name

     

    Order 1: server_DC1/vs_name

     

    Topology Regions: (IP subnet is)

     

    region_DC1 { list of LDNS addresses }

     

    region_DR1 { list of LDNS addresses }

     

    Topology Records:

     

    Region is "region_DC1" then pool "pool_to_DC1_vs"

     

    Region is "region_DR1" then pool "pool_to_DR1_vs"

     

    WideIP:

     

    LB preferred: Topology

     

    Pools:

     

    pool_to_DC1_vs

     

    pool_to_DR1_vs

     

    Regarding balance methods, I think even when server as Generic Host, most types still can be used, but in your case, maybe "Topology" and "Global Availbility" types can statisfy your need.

     

    This is what I can think for now.

     

    Regards.