Bug ID 890229: Source port preserve setting is not honoured

Last Modified: Jun 03, 2020

Bug Tracker

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

Known Affected Versions:
13.1.0,,,,,,,,, 13.1.1,,,,,, 13.1.3,,,, 14.0.0,,,,,, 14.0.1,, 14.1.0,,,,,,, 14.1.2,,,,,, 15.0.0, 15.0.1,,,, 15.1.0,,,

Opened: Mar 16, 2020
Severity: 3-Major


The source port is always changed in source-port preserve mode even if the original source port with the other parameters would hash to the same TMM.


Applications relying on a specific, fixed source port might not work as expected.


This issue occurs when all of the following conditions are met: -- You have configured a hash that includes IP addresses, which you can accomplish in any of the following ways: + Using RSS DAG as a default hash on BIG-IP Virtual Edition (VE) (Z100) or on 2000- and 4000-series devices. + By configuring a VLAN's 'CMP Hash' setting to a non-default value. + By using a special variable like udp.hash or tcp.hash. -- The virtual server is configured with source-port preserve (the default).


Set source-port to preserve-strict.

Fix Information


Behavior Change

Beginning with v16.0.0, the TM.PortFind.Src_Preserve BigDB variable introduced in v15.1.0 is no longer supported. The source-port preserve setting now does best effort to preserve the source port.