Using the IP multicasting utilities

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

Using the IP multicasting utilities

IP multicasting utilities in the Windows Server 2003 family consist of the following:

  • The mrinfo command.

  • Netsh support for multicast troubleshooting.

  • Support for the mtrace command.

The mrinfo command

The Windows Server 2003 family includes the mrinfo command that displays the configuration of a multicast router. You can use the configuration information to aid in the troubleshooting of multicast forwarding and routing problems.

The mrinfo command queries a specified multicast router with an Internet Group Management Protocol (IGMP) message. The response to the query contains a version number, the list of interfaces and the neighbors on each interface, metrics, Time to Live (TTL) thresholds, and flags. The syntax of the mrinfo command is:

mrinfo [-n] [ -iaddress ] [ -rretry_count ] [ -ttimeout_count ] multicast_router

  • The -n option displays IP addresses in numeric format.

  • The -i option specifies the IP address of the interface from which you want to send the mrinfo query. By default, the interface from which to send the mrinfo query is determined by the IP routing table.

  • The -r option specifies the neighbor query retry limit. The default value is 3.

  • The -t option specifies how long in seconds mrinfo waits for a neighbor query reply. The default value is 4.

The following is an example of the mrinfo command:

C:\>mrinfo 10.1.0.1
10.1.0.1(test1.microsoft.com) [version 18.55,mtrace,snmp]:
10.1.0.1 -> 0.0.0.0 (local) [1/0/querier/leaf]
10.2.0.1 -> 10.2.0.2 (test2.microsoft.com) [1/0]
10.2.0.1 -> 10.2.0.3 (test3.microsoft.com) [1/0]
10.3.0.1 -> 0.0.0.0 (local) [1/0/querier/leaf]

In the above example, mrinfo is run against the multicast router at 10.1.0.1. The first line shows the multicast router configuration: version number (for servers running Routing and Remote Access, the version number reflects the build number of the operating system) and flags (mtrace and snmp supported).

Each additional line displays the interfaces on the multicast router and the neighbors on each interface. Interfaces 10.1.0.1 and 10.3.0.1 have no neighbors. Interface 10.2.0.1 has two neighbors, 10.2.0.2 and 10.2.0.3. For each line, mrinfo displays the interface and neighbor, the domain name for the neighbor, the multicast routing metric, the TTL threshold, and flags indicating its role on the network such as the IGMP querier of the network (querier) or whether it has no neighbors (leaf).

Netsh support for multicast troubleshooting

To view multicast tables and gather information to aid in the troubleshooting of multicast routing and forwarding problems, you can use the following netsh commands:

  • netsh routing ip show mfe

    Displays the entries in the multicast forwarding table. This is equivalent to the Multicast Forwarding Table available in Routing and Remote Access. To view the Multicast Forwarding Table from within Routing and Remote Access, under IP Routing, right-click General, and then click Show 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. This is equivalent to the Multicast Statistics table available in Routing and Remote Access. To view the Multicast Statistics table from within Routing and Remote Access, under IP Routing, right-click General, and then click Show Multicast statistics.

  • netsh interface ip show joins

    Displays the multicast groups locally joined on each interface.

Support for the mtrace command

Although the Windows Server 2003 family does not provide a version of the Mtrace multicasting utility, the server running Routing and Remote Access does respond to mtrace command queries from other Mtrace utilities.