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AllrecipesDCO_1's avatar
AllrecipesDCO_1
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Apr 11, 2014

Virtual Server availability between LTM and GTM

Hello,

 

We have a Virtual Server in each of our data centers, let's call it 0.0.0.1, configured in our LTM that only has an iRule as its resource. The iRule takes all requests pointed at 0.0.0.1 and redirects them to a different Virtual Server based on their HTTP referer. For instance, if a user goes to www.example.com, our DNS server points it at 0.0.0.1, and when the request arrives the LTM redirects it to 1.1.1.0. If a user goes to www.anotherexample.com, our DNS server points it 0.0.0.1 and the LTM redirects it to 2.2.2.0.

 

Since the iRule is processed on first priority, http health checks don't return anything. In our GTM, we've set up a Wide IP pool which includes 0.0.0.1, however the GTM constantly marks the Virtual Server as "Offline" since it can't verify its health (since the IP address isn't reachable). Is there a way to force the GTM to mark the server as "Available" even when the health checks can't reach it?

 

Thank you for your help!

 

application delivery
availability
BIG-IP DNS
design
LTM
management

7 Replies

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  • AllrecipesDCO_1's avatar
    AllrecipesDCO_1
    Icon for Nimbostratus rankNimbostratus
    Apr 11, 2014
    Also, for further reference, I've tried the following health monitor and it still comes back "Offline": GET / HTTP/1.0\r\nHost: www.example.com\r\n and GET / HTTP/1.0\r\nReferer: www.example.com\r\n
  • Cory_50405's avatar
    Cory_50405
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    Apr 11, 2014

    You could disable health checking completely if you have no need for it. Just remove all monitors from the GTM pool and uncheck Verify Virtual Server Availability in the pool configuration. The wide IP will still respond without health checking.

     

    • AllrecipesDCO_1's avatar
      AllrecipesDCO_1
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      Apr 11, 2014
      Awesome, thanks Cory! I just tested and this appears to work. I'll use this workaround for now, until I can find some way to get the LTM and GTM to communicate properly.
    • Cory_50405's avatar
      Cory_50405
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      Apr 11, 2014
      Is there a reason you want to pursue having a monitor on this pool if all you are doing is redirecting to other virtual servers that (hopefully) have health checking enabled? I guess I see this as more of a permanent solution versus just a work around but I'm also looking in from the outside. I'm sure you have your reasons.
    • AllrecipesDCO_1's avatar
      AllrecipesDCO_1
      Icon for Nimbostratus rankNimbostratus
      Apr 15, 2014
      I'd prefer to have the GTM actively notifying me if it's unable to send traffic there, rather than bypassing the health check and assuming that the iRule is doing its job, but I see your point, too. I guess it's more of a peace-of-mind thing for me.