IGMP/MLD version incompatibility between M5300 switches

Hi Daniel,

Thanks for taking care about this one. Here are the answers to your questions:

1) I hope I got the question right. Is your question related to having IGMP/MLD Snooping enabled on both, the access as well as the stack switch? If so, here's the answer. If not, please let me know... ;)

I've got IGMP/MLD Snooping enabled on both switches because of what I think I figured out. This is, if you do not have either of these two enabled, the M5300 is not forwarding multicast at all. At least I've seen a lot more problems regarding multicast not working as long as IGMP/MLD Snooping is not enabled on either one of the two switches. This is espacially true for IPv6 -> MLD. If I do not enable MLD Snooping, IPv6 traffic is not working propperly/reliable on the M5300 switches in general.

Furthermore, regarding the access switch I thought it might be exactly the right thing to enable IGMP/MLD Snooping on that switch because here I want the individual multicast traffic to only reach the end devices interessted in the individual multicast traffic.

2) No, I only want the stack switch do act as the IGMP/MLD querier. I guess you've seen that I also have VLANs configured for the IGMP and MLD Querier on the access switch. If you take another look you will also see that the querier role is not enabled on the access switch, neither for IGMP nor for MLD. I applied this configuration because of the following:

• As I thought, the access switch is not acting as a querier for IGMP/MLD as long as these roles are disbabled in the configuration.
• Having the VLANs configured in the IGMP/MLD Querier sections allows me to see which switch is currently being reckognized by the access switch as the querier. This is the main purpose of having the VLANs configured there.

Furthermore I think it behaves exactly like I thought it would. On the network itself - using Wireshark - I only see IGMP/MLD queries sent out by the stack switch.

---------------------------

Maybe the following explanation might be also useful to you. The scenario I'm talking about here is more ore less just an extract of our network. The stack switch described here is acctually acting as a distribution switch which and also as an area border router in our OSPF setup. Therefore I configured it to also be the MCast Router in the OSPF area it acts as the ABR for. This stack servs more than just one VLAN, as you've propperly seen already. I just wanted to make it as simple as possible when I started to describe the problem here and therefore I was just taking about one VLAN running over these two switches, especially the stack switch.

Given the fact that the stack switch acts as an ABR as well as the MCast Router for several VLANs in its area I thought it would make a lot of sence to also let this switch act as the IGMP and MLD querier so everything regarding OSPF, IGMP and MLD MCast Routing/Queriing runs at this switch.

I really hope this helps and if not, please let me know. I would be happy to help you as much as possible.

Best regards.

dialsc