Bug ID 1753029: ICMP Monitor probes can flap when there is a slight delay in the response.

Last Modified: Nov 29, 2025

Affected Product(s):
BIG_IP_NEXT(CNF) CNF(all modules)

Known Affected Versions:
1.3.2, 1.3.3

Fixed In:
1.4.0

Opened: Nov 19, 2024

Severity: 2-Critical

Symptoms

-- ICMP Connection flow timeout has been set at 1 second irrespective of the monitor timeout. -- When the ICMP probes are sent to pool members, if there is a slight delay in the response, the connection flow may be cleared even before the response is received. -- This condition causes the probe to fail and thereby marking the pool member as down.

Impact

Monitor probes fail causing the pool member to be marked down intermittently even when the actual pool member is healthy and alive.

Conditions

ICMP Connection flow timeout has been set to 1 second. If the ICMP response takes more than 1 second, the probes are marked as down.

Workaround

None

Fix Information

This issue is fixed by modifying the ICMP Connection flow timeout based on the ICMP monitor timeout.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips