The other day a colleague and I were shadowing a vendor who was installing their 3rd party application on a hosted server. The vendor went ahead and created an alias for the application but initially created it with Named Pipes. Needless to say, the alias didn't work. Given that this application is hitting against a SQL Server 2005 installation, the Named Pipes protocol is disabled by default for remote connections. Only TCP is enabled. The vendor originally went back and configured the alias to use TCP, which did work. But this got me to thinking, "Why did the vendor choose Named Pipes?"
If we look in Books Online, we see the following quote:
Generally, TCP/IP is preferred in a slow LAN, WAN, or dial-up network, whereas named pipes can be a better choice when network speed is not the issue, as it offers more functionality, ease of use, and configuration options.
This caused me to pause. Over the network I've seen issues with Named Pipes, such as unexpected disconnects that I've not seen with TCP/IP. I saw this last year, as a matter of fact, when an application would periodically disconnect from the database. The problem was that this application did not attempt to reconnect nor did it fail gracefully. It crashed out every time it lost the database connection. This application commited one of the fallacies of distributed computing: assuming the network is reliable. And this is on a modern switched LAN at typical LAN speeds.
So I'm not in agreement with the assessment given in Books Online. As a matter of fact, I would definitely disagree with respect to SQL Server 2005. In SQL Server 2005, only the TCP/IP protocol supports Kerberos authentication, which overall is a better security protocol than NTLM. Named Pipes has to use NTLM. Until SQL Server 2008, there is no option to use anything but. And even in SQL Server 2008, it means being aware of a potential additional SPN that's not needed for TCP/IP.
Which all leads to the question that's still nagging at me, "Why use Named Pipes? What's the benefit of doing so over the default of TCP/IP (or shared memory, for local connections)?"