Control of Source Routing on Token Ring IP Broadcasts

Last reviewed: March 20, 1997
Article ID: Q156384

The information in this article applies to:

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

SYMPTOMS

Attempts to pass IP broadcasts, such as DHCP traffic, over a Token Ring transparent bridge may fail. This failure results in various symptoms, such as the inability to obtain an IP address via DHCP, or the inability to resolve the names of computers on the other side of the bridge.

CAUSE

Computers running Microsoft Windows NT set the source routing bit in all IP broadcast traffic by default. Transparent bridges may discard frames with source routing information when passing them to different media types, such as Ethernet.

RESOLUTION

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

In order to configure a computer running Microsoft Windows NT version 4.0 to send IP broadcasts without source routing, the following Registry parameter must be added and set to 0:

   ArpAlwaysSourceRoute
   Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
         Tcpip\Parameters
   Value Type: REG_DWORD - Boolean
   Valid Range: 0,1 (False or True)
   Default: 0 (False)

When you set this parameter to 1, you force TCP/IP to transmit ARP queries with source routing enabled on token ring networks. By default, the stack transmits ARP queries without source routing first, and retries with source routing enabled if no reply was received. After applying the hotfix referenced in this article, adding this parameter and setting it to 0 will cause all IP broadcasts to be sent without source routing.

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.

Additional query words: prodnt
Keywords : kbbug4.00 kbnetwork NTSrv NTSrvWkst nttcp NTWkst
Version : 4.0
Platform : WinNT

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Last reviewed: March 20, 1997
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