FDDI MAC Address Issue with Windows NT 3.5 (126652)


The information in this article applies to:

  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Server 3.5
This article was previously published under Q126652

SYMPTOMS

Unlike the Ethernet standard, FDDI and TokenRing are capable of using non-canonical or canonical formatting for the MAC Address. If the MAC address for a FDDI node is 800000000000 through FFFFFFFFFFFF, and TCP/IP is being used as the transport protocol, you lose connectivity.

CAUSE

Windows NT reads the MAC addresses in canonical format and does not properly translate the most significant bit (MSB). In FDDI and TR, if the node address is 0x020406080A0C, then 0x20406080A0C0 goes out on the wire. The bit the should be checked is 0x01 instead of 0x80, for the most significant bit (for directed vs. multicast).

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.5. This problem has been corrected in the latest U.S. Service Pack for Windows NT version 3.5. 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
Modification Type:MajorLast Reviewed:10/28/2003
Keywords:KB126652
©2003 Microsoft Corporation. All rights reserved.