I was going through the IEEE 802.1Q (2018) standard on my own. The standard speaks about group addresses, and how these group addresses are learned by transit bridges, which is all fine. But how do these bridges register/subscribe/join these multicast MAC addresses? I understand there is IGMP which is a layer 3 protocol for devices to join a multicast address. But I would like to know if it is possible for joining in layer 2 itself. The standard does not go into depth about this.
So my understanding is:
- Management defines the devices (static) registered in a group OR
- There is a layer 2 protocol for dynamic registration OR
- There is no layer 2 protocol, and one needs to use a layer 3 protocol for this.