Why is Loose Close needed with nPath
Hello,
I had a case today where I was load balancing traffic to a web server with nPath (Direct server return). I encountered problems with certain API endpoints where, due to the code, there was no activity on the connection for 10-20s while server was gathering content. Connection was always terminated after some time.
After reading https://support.f5.com/csp/article/K11116, I enabled Loose Close and everything started to work. F5 describes the loose close parameter: the Loose Close option allows the system to remove a connection when the system receives the first FIN packet from either the client or the server. This helps trim connection table entries because the system can remove the connection entry as soon as the connection officially closes, and the system does not need to maintain the connection table entry.
So, I again disabled the loose close and did a tcpdump on server and client and didn't find a FIN package from neither. Why did F5 remove the connection from the connection table when loose close is disabled? Why weren't my endpoints working?
Thanks, Matej