Bug ID 1188837: Server side timewait close state causes long establishment under port reuse on i15820DF

Last Modified: Oct 04, 2024

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 16.1.5, 16.1.5.1

Opened: Nov 11, 2022

Severity: 3-Major

Symptoms

When the server TCP connection is under timewait closing state, if a new client connection is initiated towards the server under the BIG-IP SYN-Cookie mode, the server will respond with ACK instead of SYN+ACK for the SYN received. The BIG-IP system drops this ACK and retransmit the SYN, till timeout occurs.

Impact

Longer establishment time and retry.

Conditions

- Running an i15820DF BIG-IP system. - FastL4 profile with syn-cookie-enable set to "enabled". - New client connection is reusing the port to get to the same server TCP connection.

Workaround

None

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips