The information in this article applies to:
- Microsoft Windows 95
- Microsoft Windows 95 OEM Service Release 2
On a Windows 95-based computer with the Winsock2 Update for Windows 95 installed, IGMP
queries may time out prematurely. This may result in computers that are members of a
multicast group being dropped from group membership.
The TCP/IP driver in the Winsock2 Update for Windows 95 does not properly implement the
Max Response Time field as documented in the IGMP version 2 draft. This behavior may cause
clients participating in a multicast group to not respond to IGMP requests from a router
within the timeout period. When this occurs, the router no longer forwards multicast
packets to the expired group member.
This issue is resolved by the following updated file for Windows 95 and Windows 95 OEM
Service Release 2 (OSR2):
Vip.386 version 4.10.1512 (dated 7/29/97) and later
To install this update, use the following steps.
NOTE: This update should be applied only to Windows 95-based computers on which the
Winsock2 Update has been installed.
- Download the Vipup20.exe file from the Microsoft Software Library to an empty folder.
- In My Computer or Windows Explorer, double-click the Vipup20.exe file you downloaded in
- Follow the instructions on the screen.
The following file is available for download from the Microsoft Software Library:
~ Vipup20.exe (size: 176312 bytes)
For more information about downloading files from the Microsoft Software Library,
please see the following article in the Microsoft Knowledge Base:
TITLE : How to Obtain Microsoft Support Files from Online Services
The following files are installed by Vipup20.exe:
File name Version Date/Time Size Destination folder
Vip.386 4.10.1512 7/29/97 3:12p 71,754 Windows\System
The Winsock2 Update for Windows 95 is included in the Winsock2 Software Development Kit
(SDK), available from the following location on the Microsoft FTP site:
This issue is known to occur with the Vip.386 file version 4.10.1423 included in the
Ws295sdk.exe file dated 6/23/97 from the FTP location listed above. Future revisions to
this package may not exhibit this symptom.
Keywords : win95 kbfile kbnetwork kbtool kbfixlist
Version : WINDOWS:95
Platform : WINDOWS