XGEN: Changing the RPC Binding Order

ID: Q163576

The information in this article applies to:
  • Microsoft Exchange Server, versions 4.0, 5.0, 5.5
  • Microsoft Exchange Windows 3.x client, versions 4.0, 5.0
  • Microsoft Exchange Windows 95/98 client, versions 4.0, 5.0
  • Microsoft Exchange Windows NT client, versions 4.0, 5.0
  • Microsoft Outlook Windows 95/98 client, versions 8.0, 8.01, 8.02, 8.03, 8.04, 8.5, 9.0
  • Microsoft Outlook Windows NT client, versions 8.0, 8.01, 8.02, 8.03, 8.04, 8.5, 9.0
  • Microsoft Outlook for Windows 3.x, Exchange Server Edition, version 8.0
  • Microsoft Outlook for Macintosh, Exchange Server Edition, versions 8.0, 8.1
IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SUMMARY

How Exchange Server Uses RPC

Exchange Server uses remote procedure call (RPC) built into Microsoft Windows NT to establish connections among the Exchange Server processes, such as connections between Exchange Server message transfer agents (MTAs), and to connect Exchange Clients and Exchange Server computers in the network. Exchange Server can use RPC over named pipes, TCP/IP, NetBIOS, and IPX/SPX. When it uses RPC, Exchange Server proceeds through a list of those protocols and tries to establish RPC binding. The preference order of the transports is defined by the RPC Binding Order, which by default is: local RPC, TCP/IP, SPX, named pipes, and then NetBIOS (in order of preference).

Changing the RPC Protocol Binding Order

The default RPC protocol binding order is set when an Exchange Client is installed. This setting determines the protocol sequence that the client uses to communicate with Exchange Server. You can change the RPC binding order before or after the client is installed. You can improve performance by changing the RPC binding order if the client uses multiple protocols or if the single protocol your client uses is not the first listed in the RPC binding order. If the protocol that the Exchange Client uses is last in the sequence, the client attempts to bind over the protocols listed before that protocol when it connects to the server. The protocols are represented in the binding order, using the following entries. The string ncacn refers to Network Computing Architecture Connection. 

   Protocol name RPC protocol string
   ----------------------------------

   Local RPC      ncalrpc
   TCP/IP         ncacn_ip_tcp
   SPX            ncacn_spx
   Named pipes    ncacn_np
   NetBIOS        netbios
   VINES IP       ncacn_vns_spp
For example, the following entry attempts to establish connections over SPX, TCP/IP, and NetBIOS, in that order. 

   RPC_Binding_Order=ncacn_spx,ncacn_ip_tcp,netbios

Clients Running Windows 95, Windows NT Server, and Windows NT Workstation

By default, the Exchange Client uses the following RPC binding order for Windows 95, Windows NT Server, and Windows NT Workstation when it connects to an Exchange Server computer.
  1. TCP/IP


  2. SPX


  3. Named pipes


  4. NetBIOS


  5. VINES IP (Windows NT Server and Windows NT Workstation only)


You can change the RPC binding order for clients running Windows 95, Windows NT Workstation, and Windows NT Server before or after you install the Exchange Client.

Before installation:
In Setup Editor, select the Binding Order property page.
After installation:

Use the Registry Editor to modify the binding order.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).


Locate and modify the following key in the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Exchange Provider.
For example, the following entry establishes SPX, TCP/IP, and NetBIOS connections in the order indicated:
RPC_Binding_Order=ncacn_spx,ncacn_ip_tcp,netbios

Clients Running Windows and Windows for Workgroups

By default, the Exchange Client uses the following RPC binding order for Windows for Workgroups when it connects to an Exchange Server computer.
  1. Named pipes


  2. SPX


  3. TCP/IP


  4. NetBIOS


  5. VINES IP


You can change the RPC binding order for clients running Windows and Windows for Workgroups before or after you install the Exchange Client.

Before installation:
In Setup Editor, select the Binding Order property page.
After installation:
In the Exchng.ini file in the Windows folder, edit the [Exchange Provider] section. For example, the following entry in the Exchng.ini file establishes SPX, TCP/IP, and NetBIOS connections in the order indicated: 

   [Exchange Provider]
   RPC_Binding_Order=ncacn_spx,ncacn_ip_tcp,netbios

Clients Running MS-DOS

By default, the Exchange Client uses the following RPC binding order for MS-DOS when it connects to an Exchange Server computer.
  1. Local RPC


  2. Named pipes


  3. SPX


  4. TCP/IP


  5. NetBIOS


You can change the RPC binding order for clients running MS-DOS after you install MS-DOS. To change the order, edit the RPC_BINDING_ORDER line in the Mlsetup.ini file. This file is installed automatically on the client or on a network share. For example, the following entry in the Mlsetup.ini file establishes local RPC, named pipes, TCP/IP, and NetBIOS connections in the order indicated: 

   RPC_Binding_Order=ncalrpc,ncacn_np,ncacn_ip_tcp,netbios


MORE INFORMATION

You do not need to restart the computer after you modify the Exchange binding order. The Exchange Client rereads the binding when it restarts. For troubleshooting purposes, simply change the binding order in the registry (make sure the key has been fully committed to the registry), and then perform a check names from the properties for the Exchange Server service (in Control Panel, double-click Mail). You do not even need to quit the Registry Editor when you try different bindings.

IMPORTANT: You MUST use commas between binding order entries, or the binding is not read. If, for example, you use "ncacn_ip_tcp;netbios" and perform a check names, the following error is immediately displayed:

The name could not be resolved. The Microsoft Address Book was unable to
log on to the Microsoft Exchange Server computer. Contact your system
administrator if the problem persists. <ok>
If you delete the entire RPC_binding_Order subkey, the Exchange Client uses the default binding order. This may be a good quick troubleshooting step if you have concerns about incorrect entries in the binding order.

The information in this article came from the Exchange Server Resource Kit on TechNet, and from other sources.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
Q136516 XCLN: Improving Windows Client Startup Times

Additional query words: Exchange provider EXCHNG.INI XCLN XADM exclnfaq outlook

Keywords : kbsetup kbusage XGEN exc4 exc5 exc55
Version : MACINTOSH:8.0,8.1; WINDOWS:4.0,5.0,8.0,8.01,8.02,8.03,8.04,8.5,9.0; winnt:4.0,5.0,5.5
Platform : MACINTOSH WINDOWS winnt
Issue type : kbinfo


Last Reviewed: November 5, 1999
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