Bug ID 521538: Keep-alive transmissions do not resume after failover of flows on an L4 virtual, when the sequence number is known

Last Modified: Apr 10, 2019

Bug Tracker

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

Known Affected Versions:
11.2.0, 11.2.1, 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, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5

Fixed In:
12.0.0, 11.6.0 HF6, 11.5.3 HF2

Opened: May 05, 2015
Severity: 3-Major
Related AskF5 Article:
K08025400

Symptoms

After failover of an L4 flow that is using keep-alive, the keep-alive transmissions do not resume after traffic has flowed through the BIG-IP system.

Impact

Flows after failover with TCP keep-alive age out and expire even if traffic is available to set the sequence numbers. Depending on the configuration options, subsequent packets may reset or transparently create a new flow (if TCP loose initiation is enabled).

Conditions

Using HA mirroring of L4 connections, with keep-alive enabled on the profile for TCP. After a failover, there was traffic before the flow timed out, then the traffic becomes idle. If there is no traffic after failover, the correct sequence numbers are unknown, then this is expected behavior: the flow times out due to inactivity. If there is traffic after failover, the correct TCP sequence numbers are known; if there is traffic after failover, and then the flow becomes idle, keep-alive transmissions should resume.

Workaround

None.

Fix Information

Keep-alive transmissions now resume after failover of flows on an L4 virtual, when the sequence number is known

Behavior Change