Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

iRules Recipe 4: Static Maintenance Page

The Problem You wish to provide a static maintenance splash page when all members of a pool serving a Virtual Server are currently down or disabled. The Configuration # cat /var/tmp/splash-...
Updated Jun 05, 2023
Version 2.0
application delivery
irules
LTM
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I am an F5 Solutions Architect for Service Providers in the Americas, focusing on Virtualization, SP protocols (Diameter, GTP, DNS) and programmability. Prior to joining F5, I worked as a Wi-Fi Network Engineer for a large U.S. public University, as an Operations Engineer, a network management Software Engineer, and as a Technical Trainer.
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VernonWells
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Jan 04, 2017

LB_FAILED does not mean "all pool members are down". Rather, it means "a load-balancing decision cannot be made, or an attempt to proxy the traffic failed". Usually, the first happens when all members are down, but the second can occur for a variety of reasons. For example, if the pool members becomes overloaded and TCP connections timeout, then LB_FAILED will be raised.