NWLNKSPX Retransmission Problem Over a Slow Link (166475)
The information in this article applies to:
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Server 4.0
This article was previously published under Q166475
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 on how to do this, view the "Restoring
the Registry" online Help topic in Regedit.exe or the "Restoring a Registry
Key" online Help topic in Regedt32.exe.
SYMPTOMS
You may experience a slow response or your application may be disconnected
when your client/server application is running over a slow link. This most
noticeably occurs when your client/server application uses SPX as its
transport mechanism.
CAUSE
Windows NT's NWLNKSPX protocol calculates retransmission time based on the
Round Trip Time (RTT) calculation and is calculated for each packet. As a
result, the retransmission time is dynamic and adjusts itself according to
the network load and congestion. Currently there is no option in NWLNKSPX
to disable RTT and the specified static retransmission time.
RESOLUTION
Apply the latest service pack, and then update the following registry
entry:
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" online Help topic in Registry Editor (Regedit.exe) or the "Add and
Delete Information in the Registry" and "Edit Registry Data" online Help
topics in Regedt32.exe. Note that you should back up the registry before
you edit it.
- Run Registry Editor (Regedt32.exe.)
- Go to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
\NwLnkSPX\Paramete
NOTE: The above registry key is one path; it has been wrapped for
readability.
- Click Add Value from the Edit menu.
- Add the following:
Value Name: DisableRTT
Data Type: REG_DWORD
Data: 1 (Default 0)
A data value of 1 disables the Round Trip Time calculation algorithm and
the retransmission time is set to the static value determined by the
InitialReTransmissionTime, which is 500msec by default. You can adjust
the InitialRetransmissionTime to control the retransmission timer.
STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0.
This problem was corrected in the latest Microsoft Windows NT 4.0 U.S.
Service Pack. For information on obtaining the service pack, query on the
following word in the Microsoft Knowledge Base (without the spaces):
| Modification Type: | Major | Last Reviewed: | 8/9/2001 |
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| Keywords: | kbbug KB166475 |
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