Fragmentation of Multicast UDP Packets May Cause Performance Degradation and Packet Loss

ID: Q252360

The information in this article applies to:

Microsoft Windows Media Services versions 4.0, 4.1

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SYMPTOMS

Fragmentation and packet loss may occur when you deploy high bit-rate Windows Media content.

CAUSE

Windows Media Server can generate UDP packets that are greater than 1500 bytes when you deploy high bit-rate content. This can cause IP packets to be fragmented for Windows Media Server multicasts because Ethernet packets have a maximum size of 1500 bytes. Fragmentation can cause performance degradation and packet loss.

RESOLUTION

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 Media 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    Version      Size    File name   Platform  
   -------------------------------------------------------
   12/09/1999  06:24p           1,021,136 NsRex.exe   x86

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

Use Wmsu3462.exe to install the fix. Wmsu3462.exe can be downloaded from the following location:

http://download.microsoft.com/download/winmediatech40/Update/3462/WIN98/EN-US/WMSU3462.EXE

The Nsrex.exe fix cannot be extracted from the installer. You must do this using Registry Editor.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

Start Registry Editor (Regedt32.exe).

Locate the following key in the registry:
Hkey_Local_Machine\Software\Microsoft\Netshow\Rex\

On the Edit menu, click Add Value, and then add the following registry value:

Value Name: MaxPacketSize
Data Type: REG_DWORD
Value: Maximum packet size in bytes

Quit Registry Editor.

Additional query words:

Keywords :
Version : :4.0,4.1
Platform :
Issue type : kbbug