Microsoft KB Archive/258875

= BUG: Windows 2000 Multicast Groups Are Not Rejoined When Interface Is Enabled =

Article ID: 258875

Article Last Modified on 3/1/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition

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This article was previously published under Q258875



SYMPTOMS
When an interface is disabled and then re-enabled in Windows 2000 either by the user interface or through MediaSense, if the adapter was joined to multicast groups, the interface may not be able to receive multicasts from those groups once it is re-enabled. Internet Group Membership Protocol (IGMP) should be sending a join message for each group that the computer is a member of when the interface is re-enabled.



CAUSE
This problem occurs when the multicast sockets are bound to INADDR_ANY. Mulicast groups are rejoined as expected if the socket is bound to a specific interface.



Workaround
A well written application should generally monitor for address changes and should unjoin and then rejoin the multicast group when there is an address change (especially when obtaining a different IP address). You can use the SIO_ADDRESS_LIST_CHANGE option of the WSAIoctl function to receive notification of an address list change.



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

