0300 Intermittent or Periodic Network Issue
The network is mostly stable, but there are occasional issues with reliability (intermittent) or issues may happen at about the same time each day, week, or month (periodic).
- Communication Link Failure
- Connection timeout expired
- General Network Error
- Transport-level Error
- The specified network name is unavailable
- Semaphore timeout
- The wait operation timed out
- A fatal error occurred while reading from the input stream
- Protocol error in TDS stream
- The server was not found or was not accessible
- SQL Server does not exist or access denied (this can also be an authentication error)
In the context of the Workflow, the word "Client" refers to the immediate client to SQL Server, e.g. in a 3-tier application, the client could be a web server.
The initial goal is to try to isolate which of the moving parts is causing the problem. High level isolation will be Client, Server, or Network.
0300.3.1 This issue may take a while to resolve depending on the frequency that the problem occurs, whether it happens to one of many clients vs. all clients vs. application server, and whether it happens more often at set times of day, e.g. busy periods or during backups or reindexing.
0300.3.2 The most common issues are related to packet drop due to Antivirus, Network optimizations, older network drivers, bad router or switch, and not pooling connections in the application. Some causes, such as Antivirus can be difficult to prove, but are common nonetheless. You may have to uninstall and reboot the computer to prove this without hard proof. Creating an exception may work, also. But turning the AV off generally won't work because the network filter drivers are still being loaded even if they aren't being monitored.
0300.3.3 For intermittent connections to non-Microsoft databases, such as Oracle, DB/2, or MySQL, you may need to engage the appropriate vendor. Microsoft can only provide limited support in this area, such as substituting a different application or driver for the vendor's one and comparing results. Do not ask Microsoft to debug a vendor's product as that may reveal proprietary information. The vendor should be the first point of contact for issues with their product, and can work together with Microsoft on a case, should that be necessary.
0300.3.4 This workflow is designed for SQL Server client/server connections. Other communications, such asSQL Server Mirroring, Always-On, and Service Broker synchronization traffic over port 5022, are not addressed.
Please perform the initial data collection and narrowing steps: 0100 Initial Data Collection and Scoping Questions. This will help get a macro perspective of the scope of an issue, such as whether the issue affects multiple computers or just one, or whether only those computers in a specific data center are facing issues. This can help focus the troubleshooting steps. It will also make you prepared for discussing the issue with Microsoft Support should you choose to do so.