https://community.sap.com/t5/technology-q-a/understanding-the-keepalive-and-keepaliveinterval-parameters-in-sql-server/qaa-p/12725467#M4775693 <P>Below is the explanation about the parameters.</P> <P>Keep Alive: How often TCP verifies that an idle connection is still intact.<BR />Keep Alive Interval: The retry interval for unresponsive TCP Keep Alive transmissions. The default is 1000ms.</P> <P>The number of Keep Alive messages sent is controlled by TCP/IP parameter TcpMaxDataRetransmissions(default: 5) .</P> <P>When KeepAlive is set to 30 seconds and KeepAliveInterval is set to 12 seconds, the TCP keep-alive mechanism works as follows:</P> <P>1. Assume that the TCP connection is idle for a period of time. After 30 seconds of idleness, the operating system sends the first keep-alive probe packet to the remote endpoint to verify if the connection is still active.<BR />2. If the remote endpoint responds to the keep-alive probe packet, the connection remains open.<BR />3. After 12 seconds, the operating system sends another keep-alive probe packet if there is no response from the remote endpoint.<BR />4. Repeat step 3 until the maximum number of retries(which is controlled by the TCP/IP parameter TcpMaxDataRetransmissions).</P> <P> </P> <P>Given the above configuration of SQL Server clients, Keep Alive messages must be responded to by a SQL Server in no more than 90 seconds(30+12*5=90) best case. </P> <P>dbs/mss/conn_opts = KeepAlive=30;KeepAliveInterval=12. <BR />TcpMaxDataRetransmissions=5</P> <P> </P> <P>If the configuration is changed to below, then it would allow 220s(120+20*5=220).</P> <P>dbs/mss/conn_opts = KeepAlive=120;KeepAliveInterval=20,<BR />TcpMaxDataRetransmissions=5</P> <P> </P> <P>A connection disconnect error will be reported if the keep-alive probe is lost due to a remote host or network failure, or if multiple probes (default 5 in this case) are sent without receiving a response.</P> Wed, 10 May 2023 06:35:09 GMT SAPSupport 2023-05-10T06:35:09Z https://community.sap.com/t5/technology-q-a/understanding-the-keepalive-and-keepaliveinterval-parameters-in-sql-server/qaq-p/12725466 <P>I want to increase the TCP Keepalive duration in my SQL Server. <BR />Currently, the setting is dbs/mss/conn_opts = KeepAlive=30;KeepAliveInterval=12. <BR />If I change it to dbs/mss/conn_opts = KeepAlive=120;KeepAliveInterval=20, how will the behavior change?</P><BR />------------------------------------------------------------------------------------------------------------------------------------------------<BR /><B>Learn more about the SAP Support user and program <A href="https://blogs.sap.com/2021/09/20/maximizing-the-power-of-sap-community-at-product-support/" target="_blank">here</A>.</B> Wed, 10 May 2023 06:35:06 GMT https://community.sap.com/t5/technology-q-a/understanding-the-keepalive-and-keepaliveinterval-parameters-in-sql-server/qaq-p/12725466 SAPSupport 2023-05-10T06:35:06Z https://community.sap.com/t5/technology-q-a/understanding-the-keepalive-and-keepaliveinterval-parameters-in-sql-server/qaa-p/12725467#M4775693 <P>Below is the explanation about the parameters.</P> <P>Keep Alive: How often TCP verifies that an idle connection is still intact.<BR />Keep Alive Interval: The retry interval for unresponsive TCP Keep Alive transmissions. The default is 1000ms.</P> <P>The number of Keep Alive messages sent is controlled by TCP/IP parameter TcpMaxDataRetransmissions(default: 5) .</P> <P>When KeepAlive is set to 30 seconds and KeepAliveInterval is set to 12 seconds, the TCP keep-alive mechanism works as follows:</P> <P>1. Assume that the TCP connection is idle for a period of time. After 30 seconds of idleness, the operating system sends the first keep-alive probe packet to the remote endpoint to verify if the connection is still active.<BR />2. If the remote endpoint responds to the keep-alive probe packet, the connection remains open.<BR />3. After 12 seconds, the operating system sends another keep-alive probe packet if there is no response from the remote endpoint.<BR />4. Repeat step 3 until the maximum number of retries(which is controlled by the TCP/IP parameter TcpMaxDataRetransmissions).</P> <P> </P> <P>Given the above configuration of SQL Server clients, Keep Alive messages must be responded to by a SQL Server in no more than 90 seconds(30+12*5=90) best case. </P> <P>dbs/mss/conn_opts = KeepAlive=30;KeepAliveInterval=12. <BR />TcpMaxDataRetransmissions=5</P> <P> </P> <P>If the configuration is changed to below, then it would allow 220s(120+20*5=220).</P> <P>dbs/mss/conn_opts = KeepAlive=120;KeepAliveInterval=20,<BR />TcpMaxDataRetransmissions=5</P> <P> </P> <P>A connection disconnect error will be reported if the keep-alive probe is lost due to a remote host or network failure, or if multiple probes (default 5 in this case) are sent without receiving a response.</P> Wed, 10 May 2023 06:35:09 GMT https://community.sap.com/t5/technology-q-a/understanding-the-keepalive-and-keepaliveinterval-parameters-in-sql-server/qaa-p/12725467#M4775693 SAPSupport 2023-05-10T06:35:09Z