DOCUMENT:Q171061  10-AUG-2001  [winnt]
TITLE   :RIP Does Not Advertise Zero Subnets
PRODUCT :Microsoft Windows NT
PROD/VER:WinNT:4.0
OPER/SYS:
KEYWORDS:kbnetwork

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The information in this article applies to:

 - Microsoft Windows NT Server version 4.0 
 - Microsoft Routing and Remote Access Service Update for Windows NT Server version 4.0 
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SYMPTOMS
========

Your computer running both Windows NT Server and the Routing and Remote Access
service are not advertising all of the correct routes to all of your networks.
The subnets that are not being advertised are the subnets with a zero as the
last octet in the subnet ID.

CAUSE
=====

The Routing and Remote Access servers discard zero subnet advertisements.

RESOLUTION
==========

Obtain the Routing & Remote Access Service Hotfix Update mentioned below.


STATUS
======

Microsoft has confirmed this to be a problem in Routing and Remote Access Update
for Windows NT Server version 4.0. This problem was corrected in the Routing
& Remote Access Service Hotfix Update. You can obtain this update from
Microsoft's World Wide Web Site on the Internet at the following location:

   http://www.microsoft.com/ntserver/commserv/exec/feature/routing.asp

NOTE: Because the Microsoft Web site is constantly updated, the site address may
change without notice. If this occurs, link to the Microsoft home page at the
following address:

   http://www.microsoft.com/

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

The zero subnet is easier to identify using the following example:

Consider a class B address of 172.16.0.0 that is subnetted with a 255.255.192.0
mask. The valid subnet IDs will be 172.16.0.0, 172.16.64.0, 172.16.128.0, and
172.16.192.0. For this example, 172.16.0.0 is the zero subnet ID. This zero
subnet will not be advertised and, therefore, will not be reachable from other
networks.

Traditionally, a zero subnet ID was considered invalid, but the practice of
discarding these subnets is now obsolete. A complete discussion of this practice
can be found in RFC 1878, which has superceded RFC950, and can be found at the
following Internet location:

   http://www.rfc-editor.org

Additional query words: rras
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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbAudDeveloper kbRRASNTSearch kbRRASNT400
Version           : WinNT:4.0
Issue type        : kbbug

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