Bug ID 427248: CGNAT is not providing full EIM behavior when there are many connections from the same client.

Last Modified: Nov 22, 2021

Bug Tracker

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

Known Affected Versions:
11.3.0, 11.4.0

Fixed In:

Opened: Aug 06, 2013
Severity: 2-Critical


CGNAT may not maintain EIM behavior when it has many connections from the same client. A subscriber connecting through the CGNAT may not get the same translation address and port with the same subscriber and port as expected for Endpoint Independent Mapping behavior.


When this occurs, some applications may not operate correctly.


This occurs under the following conditions: LSN Pool mode = NAPT or Deterministic, Persistence = address-port, Inbound = OFF, many connections are going to the same host


To work around this issue, you can turn Inbound ON.

Fix Information

The same Client address:port now gets the same translation address:port regardless of host, which is correct behavior.

Behavior Change