Multicast boundaries and heartbeat

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

Multicast boundaries and heartbeat

The Windows Server 2003 family also provides multicast boundary and multicast heartbeat support.

Multicast boundaries

Multicast boundaries are administrative barriers to the forwarding of IP multicast traffic. Without boundaries, an IP multicast router forwards all appropriate IP multicast traffic. You can create multicast boundaries by specifying a range of IP addresses, known as a multicast scope, or by the value of the Time to Live (TTL) field in the IP header.

Scope-based boundaries

Scope-based boundaries prevent the forwarding of IP multicast traffic with a specified group IP address or range of IP addresses.

TTL-based boundaries

TTL-based boundaries prevent the forwarding of IP multicast traffic with a TTL less than a specified value. TTL-based boundaries apply to all multicast packets regardless of the multicast group. TTL-based boundaries are less effective than scope-based boundaries.

For more information, see Configure multicast boundaries.

Multicast heartbeat

Multicast heartbeat is the ability of the server running Routing and Remote Access to listen for a regular multicast notification to a specified group address to verify that IP multicast connectivity is available on the network. If the heartbeat is not received within a configured amount of time, the server running Routing and Remote Access sets a flag on the configured interface. The status of this flag can be polled by a program to provide notification that the multicast heartbeat is no longer present. For more information, see "IP Multicast Support" at the Microsoft Windows Resource Kits Web site.

For more information, see Configure multicast heartbeat.