Manual Chapter : Configuring Logging of Global Server Load Balancing Decisions

Applies To:

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BIG-IP GTM

  • 11.5.10, 11.5.9, 11.5.8, 11.5.7, 11.5.6, 11.5.5, 11.5.4, 11.5.3, 11.5.2, 11.5.1
Manual Chapter

About logging global server load-balancing decisions

When BIG-IP GTM receives a DNS query for a wide IP, in order to send a response, the system makes a load-balancing decision. The decision is based on the load-balancing method configured on the wide IP, the number of pools associated with the wide IP, and the applicable number of members in each pool.

You can send information about how GTM made the load-balancing decision to the high-speed remote logs; reviewing the logs can help determine how to fine-tune your network.

Configuring logs for global server load-balancing decisions

Ensure that at least one wide IP exists in the BIG-IP GTM configuration, and that high-speed remote logging is configured on the device.
When you want to view the global server load-balancing decisions made by GTM in the high-speed remote logs, configure the verbosity of the information that displays in the logs.
  1. On the Main tab, click DNS > GSLB > Wide IPs. The Wide IP List screen opens.
  2. Click the name of the wide IP you want to modify.
  3. From the General Properties list, select Advanced.
  4. For the Load-Balancing Decision Log setting, select the check boxes of the options that you want to include in the high-speed remote logs.
    Check-box option Log information
    Pool Selection The pool selected to answer a DNS request, and why the pool was selected.
    Pool Traversal The pools in the wide IP considered during the load-balancing decision, and why the pool was selected.
    Pool Member Selection The pool member selected to answer a DNS request, and why the member was selected.
    Pool Member Traversal The members of the pool considered during the load-balancing decision, and why the member was selected.
    Example log for a wide IP configured for Ratio load balancing when Load-Balancing Decision Log is set to only Pool Selection: 2013-03-14 15:40:05 bigip1.com to 10.10.10.9#34824: [wip.test.net A] [ratio selected pool (pool_b) with the first highest ratio counter (1)] Example log for a wide IP configured for Ratio load balancing when Load-Balancing Decision Log is set to both Pool Selection and Pool Traversal: 2013-03-14 16:18:41 bigip1.com from 10.10.10.9#35902 [wip.test.net A] [ratio selected pool (pool_a) - ratio counter (0) is higher] [ratio skipped pool (pool_b) - ratio counter (0) is not higher] [ratio reset IPv4 ratio counter to original ratios - the best had zero ratio count] [ratio selected pool (pool_a) - ratio counter (1) is not higher] [ratio selected pool (pool_b) - ratio counter (1) is not higher] [ratio selected pool (pool_a) with the first highest ratio counter (1)]