Date: Fri, 17 Jul 2020 18:07:39 +0200 From: Bernd Walter <ticso@cicely7.cicely.de> To: freebsd-net@freebsd.org Cc: Bernd Walter <ticso@cicely7.cicely.de> Subject: SCTP problem, how to debug? Message-ID: <20200717160739.GA79604@cicely7.cicely.de>
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I'm running an LED matrix with SCTP. The matrix consists from 24 raspberry pi running NFS-root FreeBSD 12.0-RELEASE (they have an SD card for u-boot and loader). A client system is running FreeBSD 12.1-RELEASE. The matrix modules have a one to many service socket. The daemon regularily sends status informations (temperature, etc.) to each association and has a second thread to receive. The client system has two deamons running. One daemon is to control power output related to temperature states. It has one thread reestablishing associations via sctp_connectx() to each of the 24 modules using a single one to many socket. Another thread collects all regular received data and updates stored values. Yet another thread sends power control data via SCTP_SENDALL, so that all modules know the maxed allowed brightness rating. The other daemon uses the same threads to reconnect and receive. It connects to the very same sockets on the modules. Another thread updates picture data and wanted power rating. That is sending picture data to the given matrix module and then SCTP_SENDALL an update trigger to all modules. That is reduced brightness at night times, ... All SCTP_SENDALL are just trigger with 0 length and different ppid values. >From time to time (1-5 days) I notice that a module won't get updates anymore. I see that the association got a SCTP_SENDER_DRY_EVENT event. Therefor my expectation is that there is nothing to send. I still see the association in the socket list and also receive the regular temperature data. However, obviously sending won't happen. The other modules still get data. When I restart the client daemon, things start to work again. Currently I'm clueless on how to debug this problem any fsurther. Doing a full network log would be too big and I'm not very experienced to understand the SCTP packets. I have no idea to see what data is in the send buffer. netstat with TCP would show send and receive queue, not so with SCTP. Data is send with a single thread, which sctp_sendmsgx() the data for all modules sequencially into the same socket. I havn't checked yet if I get an error with the write to the specific module IP. -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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