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johnestate_1382's avatar
johnestate_1382
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Feb 21, 2015

F5 GTM vs Cisco GSS

When all of the members of a Prober pool are down, GTM responds with all members/answers. vs Cisco GSS default behavior - When all of the answers/answer group down it shows no response

 

4 Replies

  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus

    On GTM it's configurable. Your problem is that GTM itself isn't responding, but passing the request through to DNS (The internal DNS on the GTM itself). That is then responding with RR records that are composed of all the pool members.

     

    To have GTM not respond if all members are down change the alternate/and or fallback LB method to drop rather that what it's currently set to (i.e. if the primary method fails, which it will if the pool members are all down, you want to drop the request).

     

    H

     

  • Yes right now I have Round Robin for Preferred and Alt method (RR/Return to DNS - ALT). Also in the past when I've tried drop for fallback method but surprisingly or unfortunately ran into a bug (which threw our F5 support off balance) that GTM response all pool members with random TTL time and we ended up with several production issues with lots of user connections to DR servers, or server with lower order...I tried preferred to Global Availability but ran into issues while setting DR setup and also if order is not properly defined (which somehow our deployment engineer always confuses/forgets to add it properly) the GTM query reply are not as expected but as configured.

     

  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus

    Have you tried putting a fix in place for that issue you say was a bug? The drop is the only way it'll really work.

     

    although you could also put an iRule in place that would intercept responses and remove all but 1 response...

     

    H