IGMP Incorrectly Sends Membership Packets to Several Group Addresses (249647)


The information in this article applies to:

  • Microsoft Windows 95
  • Microsoft Windows 95 OEM Service Release 2.1
  • Microsoft Windows 95 OEM Service Release 2.5
This article was previously published under Q249647

SYMPTOMS

The Internet Group Membership Protocol (IGMP) implementation in the Windows 95 Winsock 2 update incorrectly attempts to send membership packets to the 224.0.0.2 (All Routers) and 224.0.0.1 (All Hosts) group addresses. This is an unnecessary broadcast that may cause routers to report errors upon the receipt of these IGMP broadcasts.

CAUSE

The Winsock 2 update for Windows 95 updates the Vip.386 file that implements the IGMP protocol. This implementation of the IGMP protocol does not skip these multicast addresses when it is registering group membership.

RESOLUTION

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

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

http://support.microsoft.com/contactus/?ws=support

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-language version of this fix should have the following file attributes or later: 
   Date       Time     Version     Size     File name
   --------------------------------------------------
   1/7/2000   3:20pm   4.10.1660   75,885   Vip.386

STATUS

Microsoft has confirmed that this is a problem in Windows 95 (all versions) with the Winsock 2 update.

MORE INFORMATION

This update should be applied only to Windows 95-based computers that have the Winsock 2 update installed.

With this fix applied, multicast packets for router discovery are still broadcast when the computer first starts up, if the computer is configured to do so. This behavior is by design.

For additional information about problems resolved by this update, click the article number below to view the article in the Microsoft Knowledge Base:

174095 IGMP Query Times Out in Windows 95 with Winsock2 Update

For additional information about Windows 95 updates, click the article number below to view the article in the Microsoft Knowledge Base:

161020 Implementing Windows 95 Updates

Modification Type:MinorLast Reviewed:10/18/2005
Keywords:kbHotfixServer kbQFE kbprb kbQFE KB249647
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