A GSLB service can comprise multiple GSLB pools. A GSLB service can switch load across multiple GSLB pools based on the priority of the pools as explained in the example below or based on the geolocation.
A GSLB pool is different from a server pool. The former aggregates back-end services, while the latter aggregates servers.
- GSLB_SERVICE_ALGORITHM_GEO
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A GSLB pool is selected based on the geolocation. When
GSLB_SERVICE_ALGORITHM_GEOis selected for GSLB service, pool priority holds no significance.For more information, see Geolocation-based Load Balancing Algorithm for GSLB Members.
- GSLB_SERVICE_ALGORITHM_PRIORITY
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A GSLB pool is selected based on its priority.
The valid priority range defined is 0-100. Setting a pool’s priority to zero disqualifies it from the selection. This can be done temporarily, for example, to perform maintenance on the services comprising the pool.
Note:Setting pool priority to 0 is not the same as disabling it. A zero-priority pool will continue to be health-monitored; its state will be displayed as
UPorDOWN, and notDISABLED.
Refer to the diagrams shown below:
AppB, which corresponds to the GslbService_B, is comprised of two pools, with priorities 5 and 10. As long as the pool of highest priority (GslbPool_3) is up and not at its connection limit, all traffic will be directed to it. GslbPool_2 will remain idle. However, if a pool is inaccessible, down, or at maximum capacity, a lower priority pool will be chosen instead.
GslbPool_1 aggregates services VS-A1 through VS-A4 across which load will be balanced.
For more information, see Load Balancing Algorithms for GSLB.
Manual Resume option for GSLB Service with Priority Algorithm
Starting with Avi Load Balancer 22.1.3, a manual resume option is available for GSLB Service with priority algorithm. For more information, see Manual Resume Option for GSLB Service with Priority Algorithm.
