Event ID 41013 — RRAS IGMP Packet Discarding

Updated: November 29, 2007

Applies To: Windows Server 2008

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Internet Group Management Protocol (IGMP) maintains host group membership on a local subnet. Hosts use IGMP to communicate multicast group membership requests with their local multicast router. Routers receive the group membership requests and periodically send queries to determine which host groups are active or inactive on the local subnet.

If the IGMP router is discarding packets, support for Level 2 multicasting might fail.

Event Details

Product: Windows Operating System
ID: 41013
Source: Microsoft-Windows-RasRoutingProtocols-IGMPv2
Version: 6.0
Symbolic Name: IGMPLOG_PACKET_TOO_SMALL
Message: IGMP received a packet which was smaller than the minimum size allowed for IGMP packets. The packet has been discarded. It was received on the local interface with IP address: %1, and it came from the neighboring router with IP address: %2.

Resolve

Resend the IGMP packet with a valid size

Resend the IGMP packet with a size that is equal to or greater than the minimum size allowed for IGMP packets.

Verify

You can verify multicast routing configuration with the mrinfo command. 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 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] [ -i address ] [ -r retry_count ] [ -t timeout_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 preceding 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).

Related Management Information

RRAS IGMP Packet Discarding

Routing and Remote Access Service Infrastructure

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