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

ID: Q169691

The information in this article applies to:

Microsoft Exchange Server, versions 4.0, 5.0

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          : kbusage kbbug5.00 kbfix5.00.sp2 XFOR 
Version           : 4.0 5.0
Platform          : WINDOWS 
Issue type        : kbbug

Last Reviewed: April 30, 1999