Problems Copying Files To Novell NetWare 3.11

• Microsoft Windows NT Workstation version 3.51 and 4.0
• Microsoft Windows NT Server version 3.51 and 4.0

SYMPTOMS

You may experience problems copying files on a Token Ring network from a computer running Windows NT to a Novell server running NetWare 3.11 (or earlier).

Attempts to copy files (using File Manager, for example) over a certain size may fail with the following error :

   The Remote Computer is Not Available

CAUSE

Windows NT's Nwrdr.sys calculates an incorrect maximum packet size under these specific circumstances.

RESOLUTION

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.

To work around this problem, perform the following steps:

1. Start Registry Editor (Regedt32.exe) and go to the following subkey:

         HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NWRDR
         \Parameters\DefaultMaxPacketSize
   

         NOTE: The above registry key is one path; it has been wrapped for
         readability.
   

2. Select the DefaultMaxPacketSize parameter and set number to a MaxPktSize number minus 85.

   For example, if you have specified a MaxPktSize of 1500, you should set DefaultMaxPacketSize to 1415. That is, 1500 minus 85 = 1415.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51 And Windows NT version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

For this problem to occur, the following conditions must apply:

1. PBURST is enabled on the computer running Windows NT.

2. The NetWare server refuses the computer running Windows NT PBURST request.

3. You have specified a value for the following registry parameter:

         HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NWLinkIPX
         \NetConfig\<drivername>\MaxPktSize
   

         NOTE: The above registry key is one path; it has been wrapped for
         readability.
   

   that is smaller than the buffer size the computers would normally negotiate by default if this value was absent from the registry.

If MaxPktSize is specified, problems may be encountered when attempting to transfer files larger in size than MaxPktSize number minus 85.

Note that for the NetWare server to refuse a PBURST request it must be running a version of NetWare earlier than 3.11 (for which PBURST is not available) or it must be running NetWare 3.11 and not have PBURST.NLM loaded. In NetWare 3.12 and later, PBURST support is built into the operating system and it cannot be disabled. If the NetWare server is running 3.11 with PBURST.NLM loaded, or is running 3.12 or later, you should not see this problem.

 The Magic Number of 85 is an allowance for the following:

   Token Ring Header................ 14 bytes
   Token Ring Source Routing Info... 18 bytes max
   LLC Header.......................  3 bytes
   NCP Packet Header................ 30 bytes
   NCP Write Request................  7 bytes
   File Write Request............... 13 bytes

   Total............................ 85 bytes max