Bug ID 513213: FastL4 connection may get RSTs in case of hardware syncookie enabled.

Last Modified: Nov 07, 2022

Bug Tracker

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

Known Affected Versions:
11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.10, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2, 11.5.4, 11.5.4 HF1, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8

Fixed In:
12.0.0, 11.6.1, 11.5.4 HF2

Opened: Mar 18, 2015
Severity: 3-Major
Related Article:
K76190485

Symptoms

Occasionally, ACK is sent to server without SYN, connection get RST.

Impact

Some connections will be dropped.

Conditions

1) FastL4 virtual server. 2) Hardware syncookie enabled. 3) Might more commonly occur with forwarding virtual servers. 4) Often happens when egress router has ARP timeout.

Workaround

Configure a static ARP to all neighbors (routers) to avoid most issues.

Fix Information

An issue with hardware syncookies and FastL4 connections has been resolved.

Behavior Change