Hello all,
We would like to kindly ask for your input regarding one issue that we are currently facing. We are using Kannel version 1.4.5 to communicate with an SMSC using the UCP protocol. We have noticed in the Kannel logs that the SMSC frequently resets the connection, resulting in the following error : *2021-03-23 11:02:18 [13306] [6] ERROR: Error writing 22 octets to fd 46:* *2021-03-23 11:02:18 [13306] [6] ERROR: System error 32: Broken pipe* *2021-03-23 11:02:18 [13306] [6] ERROR: EMI2[smsc-name]: emimsg_send: write failed* *2021-03-23 11:02:18 [13306] [6] ERROR: Error writing 22 octets to fd 46:* *2021-03-23 11:02:18 [13306] [6] ERROR: System error 32: Broken pipe* *2021-03-23 11:02:18 [13306] [6] INFO: EMI2[**smsc-name**]: connecting to Primary SMSC* By investigating further with Wireshark, we found out that this most likely occurs because the SMSC sends a [FIN,ACK] signal, which Kannel simply acknowledges, instead of responding with a [FIN,ACK] itself in order to terminate the connection, and then it keeps sending messages as usual. In the same Wireshark trace, it is apparent - and may be related to the problem - that while the Deliver notification (Operation) messages from the SMSC are acknowledged, Kannel responds to only a small fraction of them with a Deliver notification (Result). Finally, we would like to add that we are also using the same Kannel binaries with a different configuration setup to communicate with another SMSC using the SMPP protocol, and none of the above issues occur in that case. Thank you in advance for your support. Best Regards, Panagiotis Markovits | Software Engineer *www.motivian.com* <http://www.motivian.com/> <https://www.linkedin.com/company/motivian> <https://www.facebook.com/motiviansa/> <https://twitter.com/motivian> <https://www.instagram.com/we.are.motivian/>
