How to use the server name parameter in a connection string to specify the client network library


This article describes how to programmatically specify the client network library in the connection string when you connect to a SQL Server database.

In Microsoft Data Access Components (MDAC) 2.6 and later, you can specify the client access library by using the
server name parameter in connection string. Therefore, you can specify a specific client access library when you are prompted by an application for a server name to which to connect. This behavior can be very useful when you are testing and troubleshooting connectivity issues for SQL Server.

For example, you can use the Osql command-line utility to connect to SQL Server and to force it to use the TCP/IP network library:
osql -Stcp:myServer,portNumber -E

Code Sample

The following Microsoft Visual C# .NET code sample demonstrates how to set the connection string. The connection string has the same format irrespective of the language that you use:
using System;
using System.Data;
using System.Data.SqlClient;

namespace getCurrentProtocol
/// <summary>
/// Main Application Driver Class
/// </summary>
class Driver
static void Main(string[] args)
string sCxn = "server=myServer;Integrated Security=SSPI; database=master";
//string sCxn = "server=np:myServer;Integrated Security=SSPI; database=master";
//string sCxn = "server=tcp:myServer;Integrated Security=SSPI; database=master";
//string sCxn = "server=rpc:myServer;Integrated Security=SSPI; database=master";
//string sCxn = "server=lpc:myServer;Integrated Security=SSPI; database=master";
string sCmd = "SELECT net_library from sysprocesses where spid=@@spid";
SqlConnection cxn = new SqlConnection(sCxn);
SqlCommand sqlCmd = new SqlCommand(sCmd, cxn);
SqlDataAdapter sqlDa = new SqlDataAdapter(sCmd, cxn);
DataTable dt = new DataTable();
Console.WriteLine("Hit ENTER to continue ...");
foreach (DataRow dr in dt.Rows)
catch (SqlException e)
Console.WriteLine("SQL Error Number: " + e.Number);
Console.WriteLine("SQL Error Message: " + e.Message);

Note the connection string and particularly the value of the server parameter:
string sCxn = "server=myServer;Integrated Security=SSPI; database=northwind"

Use the Code Sample with Various Network Libraries

The following code samples demonstrate how to use the value of the server parameter to specify various network libraries:
  • TCP/IP:
    You can optionally specify a specific port number. By default, the port is 1433.
    server=tcp:hostname, portNumber
  • Named Pipes:
    You can optionally specify a specific named pipe.
    By default, the pipe name is sql\query. If you connect to a named instance, the pipe name is typically in the following format:
  • Multiprotocol:
    You can optionally specify the underlying protocol.
    server=rpc:hostname, protocol
    The default value of the underlying protocol is determined by the operating system settings where a protocol can have any one of the following values:
    ValueUnderlying Protocol
    ncacn_npNamed Pipes
    ncacn_ip_tcpTransmission Control Protocol/Internet Protocol (TCP/IP)
    ncacn_nb_nbNetwork basic input/output system (NetBIOS) over NetBIOS Enhanced User Interface (NetBEUI)
    ncacn_spxSequenced Packet Exchange (SPX)
    ncacn_vns_sppBanyan VINES
    ncadg_ip_udpUser Datagram Protocol (UDP) datagram TCP/IP
    ncadg_ipxInternetwork Packet Exchange (IPX) datagram IPX
    ncalrpcLocal procedure call

  • Shared Memory:
  • NWlink IPX/SPX:
  • Banyan VINES:
  • Apple Talk:


For more information, visit the following Microsoft Web site:

ID d'article : 313295 - Dernière mise à jour : 12 sept. 2008 - Révision : 1