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julien_21453's avatar
julien_21453
Icon for Nimbostratus rankNimbostratus
Oct 09, 2013

GTM DNS response error

Hi everybody,

 

I am new in GTM configuration and I have some problems. Here is a little explanation of the architecture :

 

I'm using GTM in delegation for responding to a sub-zone extranet.example.com and particulary a gateway named ssl.extranet.example.com (which is a ssl server) Example.com is authoritative on another LocalDNS (on private subnet), I have configured this one for sending DNS request to the F5 GTM. I have 2 ISP and one server (ssl.extranet) which has 2 IP on each ISP.

 

My questions are : - When a client send a DNS request to ssl.extranet.example.com, I want the F5 send back the DNS response in function of the availability of each ISP. If the ISP1 is not available, I want to respond with the ISP2's IP address of the server. Is it possible ?

 

Here are the objects I have configured : I have configured on my GTM : - two listener on the public address space (1 UDP and 1 TCP) - 2 servers ( the 2 private IP of the ssl server) - 2 Virtual Server (one for each server) referecenced the 2 IP public addresses of the F5 for each ISP. - One Pool that referenced the 2 Virtual servers.

 

- One listener ssl.extranet.example.com - One zone extranet.example.com with SOA, NS and a A record associated to F5 configuration.

 

I have also associated basic gateway_icmp monitor on the object. On the ssh command line, all the ping request on my objects (server, vip, dns server, are OK. But on the F5 GUI, all the object are marked down. I don't know why.

 

Do you have some possible explanations ?

 

deployment

7 Replies

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  • Cory_50405's avatar
    Cory_50405
    Icon for Noctilucent rankNoctilucent
    Oct 09, 2013

    Do you have the ICMP monitor assigned at the pool level, or at the server level?

     

  • bboyjnr_8532's avatar
    bboyjnr_8532
    Icon for Cirrus rankCirrus
    Oct 09, 2013

    in answer to...

     

    "When a client send a DNS request to ssl.extranet.example.com, I want the F5 send back the DNS response in function of the availability of each ISP. If the ISP1 is not available, I want to respond with the ISP2's IP address of the server. Is it possible ? "

     

    This is possible with the "Global Availability" LB Method set on the WIP/GTM pool but will require monitoring set on the VS's.

     

  • julien_21453's avatar
    julien_21453
    Icon for Nimbostratus rankNimbostratus
    Oct 09, 2013

    Hi Cory, The monitor is placed on the server.

     

    Hi bboyjnr, Ok,I will check my GA configuration.

     

    • Cory_50405's avatar
      Cory_50405
      Icon for Noctilucent rankNoctilucent
      Oct 09, 2013
      Your objects being unavailable (red) from the GUI could be because of a number of reasons outside of the GTM configuration (routing, access control). Does your GTM have a route to your servers via a TMM (non-management) interface?
    • julien_21453's avatar
      julien_21453
      Icon for Nimbostratus rankNimbostratus
      Oct 10, 2013
      I don't have filter. I have the good routes on the F5 to my servers. I don't have LTM activated. On the VS, i'm seeing : "gtmd : no reply from big3d" But big3d is the LTM daemon, no ?
    • Cory_50405's avatar
      Cory_50405
      Icon for Noctilucent rankNoctilucent
      Oct 10, 2013
      Are your servers configured as Generic Host or BIG-IP System? They should be Generic Host. big3d daemon is used to communicate between F5 devices. This shouldn't come into play when attempting to run an ICMP keepalive.