Windows Multicast using IGMPv3 in IGMPv2 environment

Question

We are looking into a field issue where the network is configured for IGMPv2 but Windows appears to be ignoring that and continuing to use IGMPv3. Things seem to be working in our test lab environment. The only difference we can see between the field and our lab is that our lab is using the default gateway to send the IGMPv2 general queries and the field is using a different IP address.

Does Windows expect the IGMPv2 general queries to come from the default gateway only?

The RFC describes how IGMP negotiation should work here:

https://www.rfc-editor.org/rfc/rfc3376 section

This section says queries should be accepted from any IP address:

https://www.rfc-editor.org/rfc/rfc3376#section-5

   The all-systems multicast address, 224.0.0.1, is handled as a special
   case.  On all systems -- that is all hosts and routers, including
   multicast routers -- reception of packets destined to the all-systems
   multicast address, **from all sources**, is permanently enabled on all
   interfaces on which multicast reception is supported.  No IGMP
   messages are ever sent regarding the all-systems multicast address.

Trace from field (default gateway = 10.2.69.254)

Trace from lab where it is working (default gateway = 10.5.55.254)

Answer 1

Hello there,

You can make the registry edit and see how it goes.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\

In the right pane, right-click and select New – DWORD (32-bit value) and set its name as “IGMPVersion” , set it with the value 3

1.Version values:

2 – Support IGMP version 1

3 – Support IGMP version 2

4 – Support IGMP version 3 (default)

In the right pane, right-click and select New – DWORD (32-bit value) and set its name as “IGMPLevel” and set it to 2

0 – Disable Multicast support

1 – Support only sending IPv4 Multicast packets (do not receive)

2 – Fully participate in IGMP. Support sending and receiving Multicast packets (default)

Here is the reference download link for the IGMP values:

You can try to turn off the firewall from all profiles and see if that helps.

What about packet capturing and checking where this is getting dropped?

Packet Monitor (Pktmon) is an in-box, cross-component network diagnostics tool for Windows. It can be used for packet capture, packet drop detection, packet filtering and counting. https://learn.microsoft.com/en-us/windows-server/networking/technologies/pktmon/pktmon

Hope this resolves your Query !!

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Answer 2

it helped me as well. But I want to know if someone have full path through Group Policy Editor.

Thanks