Bug ID 477232: CGNAT translations have a higher chance of port reuse when address persistence is enabled

Last Modified: Oct 06, 2020

Bug Tracker

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

Known Affected Versions:
11.3.0, 11.4.0, 11.4.1, 11.5.0, 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

Fixed In:
12.0.0, 11.5.2, 11.4.1 HF6

Opened: Aug 28, 2014
Severity: 2-Critical
Related AskF5 Article:


When using a LSN pool with persistence mode address, in addition to reusing the same translation address for subsequent connections, the translation port also persists and is reused.


Poor utilization of available translation ports and very high levels of port reuse. In the case of TCP connections this port reuse can cause servers to reject connections because a previous connection is in the TIME_WAIT state.


LSN pool with persistence mode address.



Fix Information

An issue with excessive port reuse in CGNAT translations when using persistence mode address has been fixed.

Behavior Change