Microsoft KB Archive/306378

= SNMP sends traps from last bound IP address on interface =

Article ID: 306378

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q306378



SYMPTOMS
If your computer's network adapter is configured with one or more virtual IP addresses in addition to its primary IP address, and is also running the SNMP service, you may see in a network trace that the computer uses the last-bound virtual IP address as the source IP address in any SNMP trap frames that are generated by the computer (instead of the adapter's primary IP address). This can cause connectivity problems if the computer is part of a Windows Load Balancing Service (WLBS) server cluster.



CAUSE
This issue occurs because SNMP selects the first IP address in the list of IP addresses that are returned by TCP/IP; this is always a virtual IP address if one or more virtual IP addresses are configured.

The hotfix that is described in this article corrects this problem so that SNMP always selects a primary IP address for use as the IP source address in SNMP traps.



RESOLUTION
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:   Date         Time   Size    File name    Platform -  17-Sep-2001  11:15  24,848  Snmpapi.dll  Intel NOTE: Because of file dependencies, this hotfix requires Microsoft Windows NT 4.0 Service Pack 6a (SP6a).



WORKAROUND
To work around this issue, install another network adapter in the computer and configure it so that it uses only a primary IP address and is the first network adapter in the TCP/IP binding order. SNMP then selects the unique primary IP address of this first adapter as the source IP address in its trap frames. The other network adapter can then be dedicated for use in a WLBS cluster if required.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB306378

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