NSX-V - Multicast within Logical Switch

[yhum]

Hello,

I have a few VMs attached to same Logical Switch in NSX but spread across multiple ESXi hosts. They join the same multicast group and send multicast other others for heartbeat/healthcheck. Is multicast supported within a logical switch by default or do I need to configure IGMP snooping or Querier or some multicast related configuration on Logical Switch/DLR/ESG?

The Transport Zone and Logical Switch is configured in Unicast Mode but I don't think I have to change the mode to Multicast or Hybrid because it matter for underlay network.

I will appreciate any input.

Regards

Yhum

[Marcin4]

Hello,

Here you will find all you need Multicast Routing Support, Limitations, and Topology

[yhum]

Hello Marcin4,

thanks however the link you shared talks about multicast routing. In my case, all VMs are in the same Logical Switch so multicast routing is out of question.

Regards

[mauricioamorim · Accepted solution]

The NSX-V logical switch "reproduces switching functionality (unicast, multicast, broadcast)" - see in Add a Logical Switch

Having said that, if nothing is done regarding multicast inside a switch considering the same VLAN, this traffic will be flooded, as the switch has no knowledge about the endpoints that have joined each multicast group. In NSX-T this is treated according to the replication method chosen for the logical switch, which usually means that each packet will be copied to each host that has a VM attached to that particular logical switch.