Bug ID 2218333: Unexpected Bandwidth Controller (BWC) behavior on server-to-client UDP traffic after HA failover

Last Modified: Feb 03, 2026

Affected Product(s):
BIG-IP PEM(all modules)

Known Affected Versions:
17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3, 17.1.3.1

Opened: Jan 29, 2026

Severity: 2-Critical

Symptoms

- After HA failover, BWC throughput drops significantly below the configured limit. - BWC drop counters stop incrementing post-failover. - Issue reproducible only with UDP traffic; TCP traffic unaffected.

Impact

- UDP egress traffic is throttled below configured limit after failover. - BWC drop counters stop updating, causing inconsistent enforcement.

Conditions

- BIG-IP PEM VE (v17.1.1 / v17.1.3) in KVM/RHOSP HA pair. - Failover occurs; connection mirroring disabled. - Server-to-client UDP traffic; BWC = 1.5 Gbps.

Workaround

- Reduce BWC bandwidth to 1 Gbps, which restores expected UDP throughput. - Remove BWC-related configuration, restoring normal behavior. - Adjust RatePerUser (e.g., from 1 Gbps to 1.5 Gbps) while keeping BWC at 1.5 Gbps, which also restores expected enforcement.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips