Wrong Network Interface Is Used for Outgoing Multicast Packets When You Use the IP_MULTICAST_IF Option (301267)

The information in this article applies to:

Microsoft Windows 2000 Server SP1
Microsoft Windows 2000 Server SP2
Microsoft Windows 2000 Advanced Server SP1
Microsoft Windows 2000 Advanced Server SP2
Microsoft Windows 2000 Professional SP1
Microsoft Windows 2000 Professional SP2

This article was previously published under Q301267

SYMPTOMS

On a multi-homed Microsoft Window 2000-based computer, you may find that the IP_MULTICAST_IF option does not designate the specified network interface to use for outgoing multicast packets, when the User Datagram Protocol (UDP) socket is connected by a Connect call. As a result, multicast packets are sent from an incorrect network interface.

RESOLUTION

To resolve this problem, obtain the latest service pack for Microsoft Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

WORKAROUND

To work around this problem, use a UDP socket that is not connected. When the UDP socket is not connected with a Connect call, the IP_MULTICAST_IF option works as expected to select the interface for outgoing multicast packets.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3.

MORE INFORMATION

For more information about Microsoft Windows Sockets socket options, visit the following Microsoft Web site:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winsock/winsock/socket_options.asp

Modification Type:	Major	Last Reviewed:	6/6/2003
Keywords:	kbbug kbfix kbnetwork kbQFE kbWin2000PreSP3Fix kbWin2000sp3fix KB301267