Enabling Multicast Connectivity Between Sites

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

An increasing number of organizations use multicast communication for such multiple-user applications as video conferencing, collaborative computing, and distance learning. Computers running Windows Server 2003 can both send and receive IP multicast traffic. The Routing and Remote Access service includes the Windows Server 2003 Internet Group Management Protocol (IGMP) routing protocol component, which you can configure with IGMP router mode and IGMP proxy mode to enable the exchange of multicast packets between remote sites. The IGMP Router and Proxy routing protocol is not itself a multicast routing protocol.

When you make your demand-dial routers multicast-capable, they can listen for all multicast traffic over all site-to-site connections, they can listen for IGMP Membership Report messages, and they can update the TCP/IP multicast forwarding table so that routers can determine where to forward incoming multicast traffic.

For a site-to-site connection, use the Routing and Remote Access snap-in to enable IGMP with IGMP proxy mode on the demand-dial interface on both the calling router and the answering router, and to enable IGMP with IGMP router mode on all other interfaces internal to the site.

For more information about IP multicasting, see "Designing a TCP/IP Network" in this book and the Networking Collection of the Windows Server 2003 Technical Reference (or see the Networking Collection on the Web at https://www.microsoft.com/reskit). For more information about multiple supported multicast configurations, see the Internetworking Collection of the Windows Server 2003 Technical Reference (or see the Internetworking Collection on the Web at https://www.microsoft.com/reskit).