Bug ID 1068445: TCP duplicate acks are observed in speed tests for larger requests

Last Modified: Apr 28, 2025

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

Known Affected Versions:
16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2

Fixed In:
17.0.0, 16.1.3.1, 15.1.6.1, 14.1.5.1

Opened: Dec 16, 2021

Severity: 3-Major

Symptoms

- A lot of TCP duplicate acks are observed in speed tests for larger requests

Impact

- Reduced throughput because of duplicate ACKs and retransmissions

Conditions

Below conditions are met - Large request - fastL4 profile with PVA acceleration set - Below sys db variables are enabled tm.tcpsegmentationoffload tm.tcplargereceiveoffload - Softpva is used

Workaround

Either one of the conditions - fastL4 profile with PVA acceleration set to NONE - Disable below sys db variables tm.tcpsegmentationoffload tm.tcplargereceiveoffload

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips