SQL Server's seven network libraries (Net-Libraries) provide the communications connection between client applications and the server. To enable a client to connect to the server, the client needs to use the same Net-Library as the server. When the client is a networked system, a Windows Interprocess Communications (IPC) component provides the connection to the server. A shared memory or local named pipes connection establishes local connections. Here's an explanation of SQL Server's seven Net-Libraries.
7. Banyan VINES
No longer popular, the Banyan VINES Net-Library provides client connectivity through the Banyan VINES protocol. Implemented in the dbmsvinn.dll DLL, the Banyan VINES Net-Library is available only for NT clients.
Also no longer widely used, the AppleTalk Net-Library provides network connectivity for Apple Macintosh clients to SQL Server via the AppleTalk protocol. SQL Server implements the AppleTalk Net-Library in dbmsadsn.dll. You can use the AppleTalk Net-Library only when SQL Server is running on a Windows NT Server.
5. Shared Memory
SQL Server implements the Shared Memory Net-Library in dbmsshrn.dll. The Shared Memory Net-Library provides local connectivity for Windows 9x systems. The Shared Memory Net-Library is not available for NT clients.
4. Novell IPX/SPX
Implemented in the dbmsdspxn.dll, the Novell IPX/SPX Net-Library provides network connectivity for Windows NT and Windows 9x clients via the IPX/SPX network protocol.
The Multiprotocol Net-Library uses the Windows remote procedure call (RPC) API to provide local and networked client connectivity. SQL Server implements the Multiprotocol Net-Library in dbmsrpcn .dll. The Multiprotocol Net-Library supports encryption and the TCP/IP, NetBEUI, and IPX network protocols.
2. Named Pipes
You can use the Named Pipes Net-Library for local and networked connections. SQL Server implements the Named Pipes client Net-Library in dbnmpntw.dll. The Named Pipes Net-Library provides Windows NT and Windows 9x connectivity via the TCP/IP, NetBEUI, and NWLink network protocols. Named Pipes is the default Net-Library for Windows NT. By default, SQL Server uses named pipe \\,\pipe\sql\query for client connections and \\machinename\pipe\sql\query for network connections.
1. TCP/IP Sockets
Probably the most widely used Net-Library, the TCP/IP Sockets library provides support only for the TCP/IP protocol. SQL Server implements the TCP/IP Sockets library in dbmssocn.dll. Windows NT and Windows 9x clients support TCP/IP Sockets, which is the default Net-Library for Windows 9x clients. In its standard configuration, the TCP/IP Net-Library uses socket 1433 to open a SQL Server connection.