File Sharing Operations to a share on Local Computer may be Slow

ID: Q231790

The information in this article applies to:

SYMPTOMS

When you share files on a computer, and then connect to that sharepoint from the same computer, file operations such as XCOPY may be slow if TCP/IP is the protocol being used.


CAUSE

If for example you share out a directory named "test", and then connect to that share from the same computer it was shared from, the TCP/IP stack uses what is called the "loopback" interface. The use of the "loopback" interface is to prevent packets between the client and server (which are on the same computer) from actually being sent out on the network cable.

TCP/IP implements "nagling" and "delayed acknowledgment", even though the interface in this case is loopback. This can cause unnecessary delays.

More details on nagling are available in ftp://ftp.microsoft.com/bussys/winnt/winnt-docs/papers/tcpipimp2.doc


RESOLUTION

A hotfix is now available which disables "nagling" on the loopback interface.
A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp
The English version of this fix should have the following file attributes or later:

   Date      Time                 Size    File name     Platform
   -------------------------------------------------------------
   05/12/99  05:17p               150,192 tcpip.sys     x86
   05/12/99  05:15p               273,328 tcpip.sys     Alpha

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support


STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0.

Additional query words: 4.00 


Keywords          : kbbug4.00 kbfix4.00 
Version           : winnt:4.0
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: July 2, 1999