Forum Discussion

Cristian_Gal's avatar
Cristian_Gal
Icon for Nimbostratus rankNimbostratus
Dec 11, 2014

GTM unavailable Wide IP

I have the following issue with a GTM deployment. There is a wide ip defined that chooses between two datacenters (one of the primary, the other one secondary). When moving from primary to secondary there is a short period of time (couple of minutes) when a service is not available (pool members are disabled) and the virtual server shows a maintenance page. The problem is that GTM marks the wide IP as unavailable due to the fact that virtual servers from datacenters have no nodes available for this short period and instead of serving the query with an IP address it falls back to DNS server, even if the status of the VS is available due to the maintenance page. I've tried using monitors but since the virtual servers are on LTM's the GTM automatically seas that a VS has no nodes.

 

Is there any way I can prevent the GTM to take the wide IP offline due to this monitoring of pools ?

 

application delivery
BIG-IP DNS
LTM

5 Replies

Sort By
  • mimlo_61970's avatar
    mimlo_61970
    Icon for Cumulonimbus rankCumulonimbus
    Dec 11, 2014

    Questions. Does your wide IP have 2 pools, one for each data center, or do you have a single pool under the wide ip with both data centers in it?

     

    What is the TTL on the pool(s)?

     

  • Brad_Parker's avatar
    Brad_Parker
    Icon for Cirrus rankCirrus
    Dec 14, 2014

    I would recommend setting a fallbackIP to ensure resolution when both are down.

     

  • mimlo_61970's avatar
    mimlo_61970
    Icon for Cumulonimbus rankCumulonimbus
    Dec 15, 2014

    Agreed, but make sure Return to DNS is not set as an alternative or fallback LB method in the pools or they won't ever use the fallback IP in the wide ip.

     

  • Cristian_Gal's avatar
    Cristian_Gal
    Icon for Nimbostratus rankNimbostratus
    Dec 15, 2014

    I can use a fallback IP, I can even let DNS server to respond but this is not what I want. I need to know how I can force GTM to ignore the status of a POOL and check the status of a VS that is using that pool, VS that can respond via an irule for example if the pool is down, the status of the VS is online and available.

     

  • mimlo_61970's avatar
    mimlo_61970
    Icon for Cumulonimbus rankCumulonimbus
    Dec 16, 2014

    There is a check box at the bottom of the pool(at least in 11.2.1) labelled "Verify Virtual Server Availability". I have never used it, but I assume that will do what you are after. I would do a bit more research on this option before I used it. For instance, I don't know if it will stop sending traffic if the entire LTM is down, or under what other conditions it might send traffic to an address that can't answer.