Single Router Intranet Connected to the MBone

The Windows 2000 router can provide multicast capabilities in a single router intranet connected to the Internet MBone. In this configuration, all interfaces on are added to the IGMP routing protocol. All private subnet interfaces are configured for IGMP router mode and the Internet interface is configured for IGMP proxy mode.

Hosts joining multicast groups send IGMP Host Membership Reports, which are then copied on the Internet interface. Multicast traffic from the Internet is sent to the Internet interface. When received, the multicast traffic is forwarded to the host on the appropriate subnet. Multicast traffic sent by a host on an intranet subnet is copied to the Internet interface. The multicast router at the ISP either ignores or forwards the multicast traffic.

In this configuration, multicast traffic sent between two hosts on the private intranet is still copied to the Internet interface, resulting in inefficient use of the bandwidth of the link to the ISP. To prevent intranet multicast traffic from being copied to the Internet interface, configure the applications or the ranges of multicast addresses on your MADCAP servers on the intranet to use IP multicast addresses from the administratively scoped range of 239.0.0.0 to 239.254.255.255, and configure the appropriate scope-based boundary on the Internet interface.

The single router intranet connected to the MBone configuration is shown in Figure 4.7.

Enlarge figure

Figure 4.7 Single Router Intranet Connected to the MBone

© 1985-2000 Microsoft Corporation. All rights reserved.