Content Switching Module (CSM): Sessions stuck in closing state

Question

Hi guys,
I'm troubleshooting a CSM with 4.3(1).
We migrated a real server from windows to linux, since then lot's of sessions stuck in closing state until the idle timer expires.
I traced the traffic from the client to the csm and from the csm to the real server what I saw is the following behaviour at the end of a session:
windows real server: client sends FIN -> real server acks the FIN -> real server sends FIN -> client sends RST -> real server sends RST -> CSM deletes session from session table
The linux real server mostly behaves like the windows real server but sometimes behaves as follows:
client sends FIN -> real server sends  FIN, but does not ack the FIN sequence number of the client -> real server sends RST -> client sends RST -> CSM does not delete  session from session table, it stucks in closing state
Does anybody know how I can solve this problem of half-closed sessions other than decreasing the idle timeout?
Is it possible to configure CSM to close and delete sessions not only on FIN-ACK packets but also on RST packets?
Or to use a different fast idle timeout when sessions are half-closed?
Many thanks in advance,
Thorsten

Answer 1

Hi Fabrizio,
CSM_FAST_FIN_TIMEOUT is already set to 10 seconds.
What I found out while testing is that CSM_FAST_FIN_TIMEOUT works with configurations where idle timeout is configured > 0.
But when idle timeout is configured to 0 (what meas no idle timeout) the csm seems not to use CSM_FAST_FIN_TIMEOUT: Half closed sessions will stuck in closing state.
Any idea why cms behaves this way?
Regards,
Thorsten