For more information regarding the security incident at F5, the actions we are taking to address it, and our ongoing efforts to protect our customers, click here.

Forum Discussion

MH's avatar
MH
Icon for Altocumulus rankAltocumulus
Dec 08, 2022

GTM - Topology load balancing failover when one pool is down

Hello All, I am looking for a solution to the problem that has been raised several times, but I do not find a confirmed solution. The situation I am in is described in the following post: GTM Topolo...
application delivery
FAILOVER
gtm
Topology load balancing
Mike757's avatar
Mike757
Icon for MVP rankMVP
Dec 09, 2022

Hi xuwen,

So fallback-mode within the pools as "none" replicates the issue?

To me this makes no sense. We're talking about the LB mode within the wide-ip to choose the correct pool. The LB mode within the pools (and the fallback mode, at that!) should have no effect on that. Do you agree?

/Mike

MH's avatar
MH
Icon for Altocumulus rankAltocumulus
Dec 12, 2022

Hello,

I found documentaiton that if we set the Alternate and Fallback to None, then it will fall back and use the next avaiable pool.  This is a situation I am now testing. It woudl work in a situation with only 2 load balancing pool.  With more than 3 load balancing pools, this is not ideal, as it does not give you explicit control over the pool that is then selected as it says simply that it selects the next avaiable pool. So this is likely to be the based on the order of the pools associated with the Wide IP.

Thanks,

Michael

  • xuwen's avatar
    xuwen
    Icon for Cumulonimbus rankCumulonimbus
    Dec 12, 2022

    You set the GTM pool fallback mode to topology for test. I did not test more than 3 gtm pools. If the effect is not good, you can use the gtm iRules in the wideip, and select the correct gtm pool according to its status up status

  • xuwen's avatar
    xuwen
    Icon for Cumulonimbus rankCumulonimbus
    Dec 12, 2022

    I made a test. wideip has 3 gtm pools.  the gtm pool Load Balancing Method: Alternate set None, Fallback set None or Topology

    The test result is based on the score of the gtm pool and whether it has up status pool member(It is not related to the order value of the gtm pool in the wideip). If the highest score gtm pool has no pool member available, then select the gtm pool with the second score. At the same time, check that the second score gtm pool whether has  active pool member. If the second  has no pool members available,finally select the third gtm pool

    [mapi.bestpay.com.cn A] 
[matched topology record (ldns:(region:/Common/all_ctc), server:(region:/Common/Region_CTC_GSLB_Pool), score:2000) to pool (gslb_pool_bestpay_ctc_v4)] 
[matched topology record (ldns:(region:/Common/Other_Region), server:(region:/Common/Region_CUC_GSLB_Pool), score:5) to pool (gslb_pool_bestpay_cuc_v4)] 
[matched topology record (ldns:(region:/Common/Other_Region), server:(region:/Common/Region_CMCC_GSLB_Pool), score:8) to pool (gslb_pool_bestpay_cmcc_v4)] 
[topology selected pool (gslb_pool_bestpay_cmcc_v4) - topology score (8) is higher] 
[topology selected pool (gslb_pool_bestpay_ctc_v4) - topology score (2000) is higher] 
[topology skipped pool (gslb_pool_bestpay_cuc_v4) - topology score (5) is not higher] 
[topology selected pool (gslb_pool_bestpay_ctc_v4) with the highest topology score (2000)] 
[topology selected pool (gslb_pool_bestpay_ctc_v4)] 
[pool member select check failed (vs_ctc_97_22:58.213.97.22) - pool member is disabled] 
[pool member select check failed (vs_ctc_97_23:58.213.97.23) - pool member is disabled] 
[round robin failed to select a pool member] 
[failed to select pool member by preferred load balancing method] 
[Using none load balancing method] 
[failed to select pool member by alternate load balancing method] 
[Using none load balancing method] 
[failed to select pool member by fallback load balancing method] 
[topology selected pool (gslb_pool_bestpay_cuc_v4) - topology score (5) is higher] 
[topology selected pool (gslb_pool_bestpay_cmcc_v4) - topology score (8) is higher] 
[topology selected pool (gslb_pool_bestpay_cmcc_v4) with the highest topology score (8)] 
[topology selected pool (gslb_pool_bestpay_cmcc_v4)] 
[pool member select check failed (vs_cmcc_99_22:58.213.99.22) - pool member is disabled] 
[pool member select check failed (vs_cmcc_99_23:58.213.99.23) - pool member is disabled] 
[round robin failed to select a pool member] 
[failed to select pool member by preferred load balancing method] 
[Using none load balancing method] 
[failed to select pool member by alternate load balancing method]
 [Using none load balancing method] 
[failed to select pool member by fallback load balancing method] 
[topology selected pool (gslb_pool_bestpay_cuc_v4) - topology score (5) is higher] [topology selected pool (gslb_pool_bestpay_cuc_v4) with the highest topology score (5)] [topology selected pool (gslb_pool_bestpay_cuc_v4)] 
[pool member check succeeded (vs_ctc_98_23:58.213.98.23) - pool member state is available (green)] [round robin selected pool member (vs_ctc_98_23:58.213.98.23)]