This is happening on a server that has been in constant use for over a year, with SQL Server 2008 and the web applications all hosted on the same machine. This morning i had 100-or-so emails with errors from the server that looked like so:
1: Error Description: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - Only one usage of each socket address (protocol/network address/port) is normally permitted.)
This happened at around 5:30am, then around 9am, then around 11am, and again around 3pm. I can see these errors in the Event Viewer, but SQL Server seems oblivious of any problem (nothing in the logs there).
i looked here already: http://blogs.msdn.com/b/spike/archive/2008/08/26/provider-tcp-provider-error-0-only-one-usage-of-each-socket-address-protocol-network-address-port-is-normally-permitted.aspx but all of our applications look like they have 'pooling=true' in their connection strings.
Running 'netstat -aon' shows that there are lots of waiting connections:
TCP 10.208.210.239:65529 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65530 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65531 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65532 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65533 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65534 10.208.210.239:55823 TIME_WAIT 0 TCP 10.208.210.239:65535 10.208.210.239:55823 TIME_WAIT 0
(10.208.210.239 is the server's internal ip, and 55823 is the port that SQL Server listens on)
That last one is from port 65535, isn't that the last one for dynamic ports?
Any thoughts would be much appreciated - do i need to try to start tracking down connections not being closed properly in applications on this server? There hasn't been a big increase in use/traffic on this server, any pointers at what to look at to try to determine why this has started happening now?