IGMPv3 Querier General messages not reaching device with IGMPv2

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IGMPv3 Querier General messages not reaching device with IGMPv2

Hi brain trust,


I have one device that doesn't seem to properly respond to IGMPv3 general messages.  Or so I thought. 

Here is a packet capture snapshot, filtered for IGMP.  Notice the lack of IGMP requests.. 
I'm trying to track down if this is a MS switch querier issue, or the device not properly sending the initial membership report message. 


Switch - MS250-48

Pcap is 3 mins long, to give time for multiple requests from the Querier


Any ideas of what I should be tracking down?  

Kind of a big deal
Kind of a big deal

As for IGMP version for IGMP snooping purposes, you cannot configure the IGMP version. Only version 3 is supported. However, IGMPv3 is backward compatible with IGMPv2. The only real IGMP packets you'll see transmitted by a switch performing IGMP snooping will be IGMP general query packets.


IGMPv3 query packets are processed in a fully backward compatible manner by IGMPv2 hosts. The only difference between an IGMPv3 general query versus IGMPv2 is that the IGMP payload of the v3 packet has some additional fields present in it not used by IGMPv2 hosts.


These are the fields that extend the IGMP payload beyond 8 bytes. However, this extra data is simply ignored by an IGMPv2 host, per IGMPv2 RFC 2236:


2.5. Other fields

   Note that IGMP messages may be longer than 8 octets, especially
   future backwards-compatible versions of IGMP.  As long as the Type is
   one that is recognized, an IGMPv2 implementation MUST ignore anything
   past the first 8 octets while processing the packet.  However, the
   IGMP checksum is always computed over the whole IP payload, not just
   over the first 8 octets.

Thanks for the response alemabrahao, 
I'm aware of those details. However I do find strange that device does not receive any general messages from the querier, where other devices on the same Vlan do. 

Shouldn't I see messages from the querier on that port?


Have you configured the IGMP querier?


IGMP Querier

An IGMP querier is required for IGMP snooping to operate per RFC4604. To configure an IGMP querier:

  1. Navigate to Switch > Configure > Routing and DHCP.
  2. Select or Add an interface.
  3. Enter Name, Interface IP, and VLAN.
  4. Under multicast support, selection Enable IGMP snooping querier.



Yes IGMP querier is set up. Please see snapshot



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