Bug ID 555020: TCP handshake may fail on layer 7 VIPs in Software syncookiemode

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
12.0.0, 12.0.0 HF1, 12.0.0 HF2

Fixed In:
12.1.0, 12.0.0 HF3

Opened: Oct 29, 2015
Severity: 3-Major


As a result of a known issue the BigIP may reset attempts to connect to a L7 VIP when in Software syncookie mode.


Connection will be reset.


- L7 VIP with a TCP profile that allows windowscaling. - Software syncookies have been activated.


Choose or create a TCP profile that has either one of the following: - "Timestamps Extension for High Performance (RFC 1323)" option in the TCP profile disabled - Values higher than 65535 in "Receive Window" and "Send Buffer" fields

Fix Information

Connections are no longer reset when connecting to a L7 VIP on a BigIP in software Syncookie mode

Behavior Change