Microsoft KB Archive/242022

= INFO: DCOM Does Not Support Any Datagram (UDP) Protocols =

Article ID: 242022

Article Last Modified on 5/28/2003

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APPLIES TO

 Microsoft COM+ 1.0, when used with:  Microsoft Windows 2000 Standard Edition

 Microsoft Windows XP Professional  Microsoft COM+ 1.5, when used with:  Microsoft Windows 2000 Standard Edition

 Microsoft Windows XP Professional</li></ul> </li></ul>

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This article was previously published under Q242022

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SUMMARY
The default protocol for Distributed Component Object Model (DCOM) protocol on Windows 2000 and Windows XP is connection-oriented Transmission Control Protocol/Internet Protocol (TCP/IP) protocol. DCOM on Windows 2000 and Windows XP does not support any of the datagram protocols.

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MORE INFORMATION
DCOM exposes its security model through Remote Procedure calls (RPC) and Security Support Provider Interface (SSPI). Beginning with Windows 2000 adn Windows XP, DCOM supports a variety of Security Providers (SSP), including the following:


 * Kerberos protocol SSP
 * Microsoft Windows NT LAN Manager (NTLM) SSP
 * Simple GSS-API Negotiation Mechanism (Snego) SSP

Because some of these SSPs do not support datagram protocols, DCOM using RPC and SSPI use the connection-oriented protocols.

To eliminate a 30-45 second delay when connecting to a DCOM server on Windows 2000 and Windows XP, move "Connection-oriented TCP/IP" protocol to the top of the DCOM protocols list in the DCOMCNFG/Default Protocols tab on Windows NT 4.0-based clients. You must restart the computer for the change to take effect.

NOTE: This delay occurs only if you haven't recently connected to the target server (because DCOM Service Control Manager caches RPC binding handles, any client re-activating the server by using the same security context uses the cached binding handle, and therefore uses the protocol that worked in the past).

The following is a list of the transport protocols that DCOM uses, depending on the client/server platform:

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