Microsoft KB Archive/169691

= XCON: MTA Exhibits Slow Performance to X.400 Links When There Is a Slow Link =

Article ID: 169691

Article Last Modified on 10/28/2006

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APPLIES TO


 * Microsoft Exchange Server 4.0 Standard Edition
 * Microsoft Exchange Server 5.0 Standard Edition

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This article was previously published under Q169691





SYMPTOMS
The Microsoft Exchange Server message transfer agent (MTA) delivers mail extremely slowly on computers that have multiple X.400 links over TCP/IP if some of the TCP/IP connections are over slow network links.



CAUSE
Flow control within the MTA code above the WINSOCK layer (within the TP0 Transport layer for TCP/IP or Session layer for TP4) for the slowest connection is stalling mail for faster connections.



STATUS
Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 4.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K



MORE INFORMATION
With the fix applied, the MTA changes the flow control method within the OSI stack above the TCP/IP (or TP4) connection to allow WinSock to handle flow control. This will make the X.400 links faster because WinSock is multithreaded and can handle as much as the MTA can hand to it.

Keywords: kbqfe kbhotfixserver kbbug kbfix kbusage KB169691

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