Bug ID 617862: Fastl4 handshake timeout is absolute instead of relative

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
11.6.1

Fixed In:
13.0.0, 12.1.2, 11.6.1 HF2, 11.5.4 HF3

Opened: Sep 20, 2016
Severity: 3-Major
Related AskF5 Article:
K61421029

Symptoms

TCP connections that are pending completion of the three-way handshake are expired based on the absolute value of handshake timeout. For example, if handshake timeout is 5 seconds, then the connection is reset after 5 seconds of receiving the initial SYN from the client.

Impact

Connections are expired prematurely if they are still in three-way handshake.

Conditions

A TCP connection in three-way handshake.

Workaround

Disable handshake timeout. Impact of workaround: Your TCP handshake will not prematurely timeout and connections remains open until the Idle Timeout expires.

Fix Information

The handshake timeout now expires based on idleness of the connection, taking into consideration of any SYN retransmissions, etc., that might occur.

Behavior Change