Bug ID 608991: BIG-IP retransmits SYN/ACK on a subflow after an MPTCP connection is closed

Last Modified: Oct 16, 2023

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

Known Affected Versions:
11.5.0, 11.5.1, 11.5.2, 11.5.3, 11.5.4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 11.5.10, 11.6.0, 11.6.1, 11.6.2, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 11.6.5.3, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2, 12.1.0, 12.1.1, 12.1.2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3

Fixed In:
13.0.0, 12.1.3.4

Opened: Aug 03, 2016

Severity: 3-Major

Symptoms

If a SYN with MP_JOIN is received on a new subflow during an MPTCP connection and the connection closes before the three-way handshake is complete, the BIG-IP will continue trying to complete the three-way handshake.

Impact

The BIG-IP retransmits the SYN/ACK to the joining flow after the connection is closed.

Conditions

A TCP profile with Multipath TCP enabled is attached to a virtual server, and a SYN with MP_JOIN is received on another flow during an MPTCP connection.

Workaround

There is no workaround

Fix Information

Free joining connections when an MPTCP connection is closed.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips