Enabling IP multicast

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta

Enabling IP multicast

To enable multicast conferencing on your network, you must install Active Directory and configure a server with the MADCAP service. The steps are listed in Checklist: Installing IP multicast video conferencing.

For more information about MADCAP and the Microsoft implementation of multicast conferencing, see How TAPI supports IP multicast video conferencing.

Checking routers on your network

The Windows Server 2003 family provides the following support for troubleshooting multicast routing and forwarding problems:

  • The mrinfo command displays the configuration of a multicast router.

  • The following netsh commands display multicast group tables and troubleshooting information for interfaces.

    • netsh routing ip show mfe displays the entries in the multicast forwarding table.

    • netsh routing ip show mfestats displays packet statistics and input and output interface information for multicast forwarding entries in the multicast forwarding table.

    • netsh interface ip show joins displays the multicast groups locally joined on each interface.

  • Although the Windows Server 2003 family does not provide a version of the Mtrace multicasting utility, a multicast router running Windows Server 2003 does respond to mtrace command queries from other Mtrace utilities.

For more information about how to use the mrinfo command and netsh commands for troubleshooting multicast routing and forwarding problems, see Using the IP multicasting utilities. For general information about how to use Netsh, see Netsh overview.

Configuring routers on your network

If there is a router on your network and you want to enable multicast conferencing across the router, you may have to configure your router to handle multicast packets. This can involve several steps:

  1. Enable multicast for the network (globally).

  2. Determine the interfaces on which to use multicast, and enable multicast on those interfaces.

  3. Enable multicast routing protocols on specific devices. For example:

    • PIM Sparse mode for links that have limited bandwidth.

    • PIM Dense mode for links that have broad bandwidth.

    • DVMRP

  4. Create access lists specifying the range of multicast group addresses allowed to cross the router.

  5. Associate access lists with specific interfaces on different routers.

To configure routing services, see Routing. To configure a particular router, refer to the documentation provided by the manufacturer.