Q150559: New Windows NT TCP/IP Registry Parameter: ArpTRSingleRoute

Article: Q150559
Product(s): Microsoft Windows NT
Version(s): 3.51
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 14-MAR-2002

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The information in this article applies to:

- Microsoft Windows NT Workstation version 3.51 
- Microsoft Windows NT Server version 3.51 
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SUMMARY
=======

A new, configurable TCP/IP parameter has been added to the Windows NT Registry.
In order to use the new parameter, you must obtain a new Tcpip.sys driver. This
driver will be released in Service Pack 5, but can be obtained in the meantime
by contacting Microsoft Product Support.

The parameter is described below:

  ArpTRSingleRoute
  Key: Tcpip\Parameters
  Value Type: REG_DWORD - Boolean
  Valid Range: 0,1 (False or True)
  Default: 0 (False)
  Description: Setting this parameter to 1 causes ARP broadcasts that are
  source-routed (Token Ring) to be sent as single-route broadcasts instead
  of all-routes broadcasts.

MORE INFORMATION
================

In a Token Ring network, when an all-routes broadcast is sent, a copy of the
broadcast will be delivered to each of the other rings by each available path.
This will generally result in multiple copies being delivered to a given ring. A
system responding to the broadcast will respond to each of the packets it
receives, and the routing information added to each response will cause it to
follow the same route back to the original broadcaster, who will receive
multiple responses, each via a different route. The broadcaster is then free to
choose which route to use for future communications. Most implementations choose
the first response.

When a single-route broadcast is sent, the source routing bridges will only
deliver one copy of the broadcast to each of the other rings. The broadcaster
will only receive a single response, and it will use the route contained in the
response for future communications.

ARP is the protocol used by TCP/IP to map an IP address to a hardware address.

By default, Windows NT TCP/IP tries ARPs in the following sequence when
attempting to locate an IP address on a Token Ring network:

1. Broadcast ARP, not source routed.

2. Broadcast ARP, source-routed, all routes.

3. Broadcast ARP, not source routed.

4. Broadcast ARP, source-routed, all routes.

Adding the ArpTRSingleRoute Registry parameter and setting it to "1" will cause
the second and fourth ARPs to be single-route broadcasts, instead of all-routes
broadcasts.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 3.51. This
problem was corrected in the latest Windows NT 3.51 U.S. Service Pack. For
information on obtaining the Service Pack, query on the following word in the
Microsoft Knowledge Base (without the spaces):

  S E R V P A C K


Additional query words: prodnt

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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNT351search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS351 kbWinNTS351search
Version           : :3.51

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