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XGEN: Changing the RPC Binding Order

This article was previously published under Q163576
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 asconnections between Exchange Server message transfer agents(MTAs), and to connect Exchange Clients and Exchange Server computers in thenetwork. Exchange Server can use RPC over named pipes, TCP/IP,NetBIOS, and IPX/SPX. When it uses RPC, Exchange Serverproceeds through a list of those protocols and tries toestablish RPC binding. The preference order of the transports is defined bythe RPC Binding Order, which by default is: local RPC, TCP/IP, SPX, namedpipes, and then NetBIOS (in order of preference).

Changing the RPC Protocol Binding Order

The default RPCprotocol binding order is set when an Exchange Client is installed. This setting determines the protocol sequence thatthe client uses to communicate with Exchange Server. You can change theRPC binding order before or after the client is installed. You canimprove performance by changing the RPC binding order if the client uses multipleprotocols or if the single protocol your client uses is not the firstlisted in the RPC binding order. If the protocol that the Exchange Client uses is last in thesequence, the client attempts to bind over the protocolslisted before that protocol when it connects to the server. The protocols arerepresented in the binding order, using the following entries. The stringncacn 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 overSPX, 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 bindingorder for Windows 95, Windows NT Server, and Windows NT Workstation when itconnects 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 youinstall 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.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows


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, andNetBIOS 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 bindingorder 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 andWindows for Workgroups before or after you install the ExchangeClient.

Before installation:
In Setup Editor, select the Binding Order property page.
After installation:
In the Exchng.ini file in the Windows folder, edit the [ExchangeProvider] section. For example, the following entry in the Exchng.ini fileestablishes SPX, TCP/IP, and NetBIOS connections in the orderindicated:
   [Exchange Provider]   RPC_Binding_Order=ncacn_spx,ncacn_ip_tcp,netbios					

Clients Running MS-DOS

By default, the Exchange Client uses the following RPC bindingorder 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 afteryou install MS-DOS. To change the order, edit the RPC_BINDING_ORDERline in the Mlsetup.ini file. This file is installed automatically on theclient or on a network share. For example, the following entry in theMlsetup.ini file establishes local RPC, named pipes, TCP/IP, andNetBIOS 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 thebinding when it restarts. For troubleshooting purposes, simply change thebinding order in the registry (make sure the key has been fully committedto the registry), and then perform a check names from the properties forthe 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 acheck 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 ExchangeClient uses the default binding order. This may be a good quicktroubleshooting step if you have concerns about incorrect entries in thebinding order.

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

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
136516 XCLN: Improving Windows Client Startup Times
Exchange provider EXCHNG.INI XCLN XADM exclnfaq outlook
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Article ID: 163576 - Last Review: 10/28/2006 18:35:40 - Revision: 3.6

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