RIP Routes May Expire Early When Running Windows NT 4.0 RIP

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

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

Routes may appear in the route table as having a metric of 16. A Routing Information Protocol (RIP) route with a metric of 16 is defined as "unreachable." This can cause difficulties with connectivity to remote resources or can cause connections to use another router.

CAUSE

There is a problem in Iprip.dll that causes route entries to expire, thus causing routes to time out early. Additionally, for very low values of RouteTimeOut, it may still be necessary to make a registry change to prevent early route expiration, as described here.

For more information on RouteTimeOut, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q169161
   TITLE     : Registry Parameters for RIP for IP version 1

RESOLUTION

To resolve this problem, obtain the following fix or wait for the next Windows NT service pack.

This fix should have the following time stamp:

   12/03/97  04:17p     53,520 Iprip.dll (Alpha)
   12/03/97  04:20p     34,576 Iprip.dll (Intel)

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.

1. Start Registry Editor (Regedt32.exe).

2. Go to the following subkey in the registry:

         HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Iprip
         \Parameters\MaxTimedOpsInterval
   

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

3. Click Edit, click Add Value and then enter the following information:

         Parameter Type: REG_DWORD
         Default:        10 (seconds)
         Range:          1-0xffffffff
         Description:    This registry value sets the maximum amount of time
                         allowed between invocations of the routine that
                         performs route maintenance. In effect, it controls
                         the granularity of the amount of time that can be
                         decremented from each route's expiration time. It
                         should be set to a value less than the difference
                         between RouteTimeOut and the RIP announcement
                         interval. Microsoft does not recommend setting the
                         parameter to any value greater than the default of 10
                         seconds.
   
   

4. Exit Registry Editor.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.