Bug ID 871509: On BIG-IP 4000 (C113) with Large Receive Offload (LRO) enabled, sometimes ACKs fail to reach TMM when there are out of order packets on the interface

Last Modified: Apr 17, 2024

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

Known Affected Versions:, 13.1.3,,,,,,, 13.1.4,, 13.1.5,, 14.0.0,,,,,, 14.0.1,, 14.1.0,,,,,, 14.1.2,,,,,,,,, 14.1.3,, 14.1.4,,,,,,, 14.1.5,,,,,, 15.0.0, 15.0.1,,,,, 15.1.0,,,,,, 15.1.1, 15.1.2,, 15.1.3,, 15.1.4,, 15.1.5,, 15.1.6,, 15.1.7, 15.1.8,,, 15.1.9,, 15.1.10,,,, 16.0.0,, 16.0.1,,

Opened: Jan 21, 2020

Severity: 3-Major


On hardware platforms like BIG-IP 4000, which does not have the Broadcom switch, sometimes the NIC fails to forward the ACKs to TMM. This leads to TMM retransmitting the FINs multiple times. If the ACKs are for FIN and if there is an intermediate router, the router closes the connection which causes the retransmitted FINs and ACKs to never reach the endpoints, leading to the BIG-IP system resetting the connection.


Excessive retransmissions and slow connection closure.


-- Hardware platforms that do not contain a Broadcom switch, such as the BIG-IP 4000. -- LRO sys db variable is enabled (tm.tcplargereceiveoffload).


Disable LRO: tmsh modify /sys db tm.tcplargereceiveoffload value disable

Fix Information


Behavior Change

Guides & references

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