Data Transfer to "Localhost" or Loopback Address Is Slow

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Article ID: 294769 - View products that this article applies to.
This article was previously published under Q294769
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SYMPTOMS

When you perform a data transfer within the same computer by using sockets, performance may be slow when you use the loopback address (127.0.0.1) or "localhost" as the destination. The slow performance does not occur if you use the local computer name or its regular IP address. The following sample results demonstrate this behavior:
Server: Localhost
32737 --> 26,326 KB/s
32738 --> 26,846 KB/s
32739 --> 80.99 KB/s
32740 --> 72.19 KB/s

Server: Computer name
32737 --> 26,014 KB/s
32738 --> 26,895 KB/s
32739 --> 25,818 KB/s
32740 --> 27,562 KB/s

CAUSE

When you use the loopback address, Windows 2000 uses a large MTU size (32 KB) that introduces TCP window timing problems.

The problem does not occur in Microsoft Windows NT 4.0.

RESOLUTION

Windows 2000

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
260910 How to obtain the latest Windows 2000 service pack
The English version of this fix should have the following file attributes or later:
   Date         Time   Version        Size     File name
   --------------------------------------------------------
   05-Dec-2000  19:12  5.0.2195.3055  118,704  Afd.sys
   09-Apr-2001  14:34  5.0.2195.3417  104,720  Msafd.dll
   09-Apr-2001  14:25  5.0.2195.3475  311,472  Tcpip.sys
   06-Apr-2001  16:55  5.0.2195.3474   16,208  Tdi.sys
   09-Apr-2001  14:34  5.0.2195.2104   17,680  Wshtcpip.dll
				

Windows Millennium Edition

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=support
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:
   Date         Time   Version      Size     File name
   ---------------------------------------------------
   24-Jan-2002  12:54  4.90.3003.0  224,432  Tcpip.sys
				

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows 2000 Service Pack 3.

MORE INFORMATION

For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:
265173 The Datacenter Program and Windows 2000 Datacenter Server Product
For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:
296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot
For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:
249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes
For additional information about Windows Me hotfixes, click the article number below to view the article in the Microsoft Knowledge Base:
295413 General Information About Windows Millennium Edition Hotfixes

Properties

Article ID: 294769 - Last Review: January 31, 2007 - Revision: 3.7
APPLIES TO
  • Microsoft Windows 2000 Service Pack 1
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Service Pack 1
  • Microsoft Windows Millennium Edition
Keywords: 
kbbug kbfix kbwin2000presp3fix kbqfe kbwin2000sp3fix kbnetwork kbhotfixserver KB294769

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