Bug ID 921477: Health monitors may fail when the HTTP RFC Compliance option is enabled in a dual BIG-IP setup.

Last Modified: Jan 20, 2023

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 13.1.3, 13.1.3.1, 13.1.3.2, 13.1.3.3, 13.1.3.4, 13.1.3.5, 13.1.3.6, 13.1.4, 13.1.4.1, 13.1.5, 13.1.5.1, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.0.0.5, 14.0.1, 14.0.1.1, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 14.1.2.2, 14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 14.1.2.8, 14.1.3, 14.1.3.1, 14.1.4, 14.1.4.1, 14.1.4.2, 14.1.4.3, 14.1.4.4, 14.1.4.5, 14.1.4.6, 14.1.5, 14.1.5.1, 14.1.5.2, 14.1.5.3, 15.0.0, 15.0.1, 15.0.1.1, 15.0.1.2, 15.0.1.3, 15.0.1.4, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2, 16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3

Opened: Jun 26, 2020
Severity: 4-Minor

Symptoms

With the HTTP RFC enforcement profile option enabled, incoming health monitor requests without an HTTP version in the request line (HTTP/0.9) may fail to produce the correct result for dual BIG-IP configurations. This can result in incoming health monitor traffic being incorrectly blocked when traveling through a virtual server. These health monitors will be unable to provide the correct availability of the intended resource. The default HTTP and HTTPS monitors as well as any custom monitors with a missing HTTP version in their requests could see this issue.

Impact

Rather than receiving the correct health check result, the original BIG-IP system can fail to report whether the second BIG-IP is available.

Conditions

A dual BIG-IP configuration may provisioned with the following considerations. -- One or more BIG-IP systems are in the network path for monitor traffic. -- The first BIG-IP system uses a health monitor that initiates a health check request (without an HTTP version) in the request line (HTTP/0.9) against a second BIG-IP system. -- The second (downstream) BIG-IP system has a virtual server that is the endpoint for the monitor. The virtual server is configured with an HTTP profile with the HTTP RFC Compliance profile option selected.

Workaround

You can use http_head_f5 monitor to perform health checks.

Fix Information

None

Behavior Change