If RouteTimeOut Is Set to a Value Lower Than the Default of 180 Seconds, Routes May Expire Prematurely

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.

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:

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

After applying the hotfix, if you have modified the RouteTimeOut registry value to time out routes in less than the default value of 180 seconds, it may be necessary to adjust the granularity of the timeout routine. This can be accomplished with the new MaxTimedOpsInterval registry parameter, as follows:

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\MaxTimedOpsInterv
   
   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.

For example, if you set the RouteTimeOut value to its minimum of 20 seconds and your router(s) sends RIP announcements every 15 seconds, this value should be set to 4 seconds or less.

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.