What Are The Multicast Bridging Features; What Is L2 Multicast Traffic - Dell M6220 User Configuration Manual

What Are the Multicast Bridging Features?

The PowerConnect M6220, M6348, M8024, and M8024-k switches support
multicast filtering and multicast flooding. For multicast traffic, the switch
uses a database called the Layer 2 Multicast Forwarding Database (MFDB) to
make forwarding decisions for packets that arrive with a multicast destination
MAC address. By limiting multicasts to only certain ports in the switch,
traffic is prevented from going to parts of the network where that traffic is
unnecessary.
When a packet enters the switch, the destination MAC address is combined
with the VLAN ID, and a search is performed in the Layer 2 MFDB. If no
match is found, then the packet is flooded. If a match is found, then the
packet is forwarded only to the ports that are members of that multicast
group within the VLAN.
Multicast traffic destined to well-known (reserved) multicast IP addresses
(control plane traffic) is always flooded to all ports in the VLAN. The well-
known IP multicast addresses are 224.0.0.x for IPv4 and FF0x:: for IPv6.
Multicast data traffic is flooded to all ports in the VLAN if no multicast
router ports have been identified. Once a multicast router port is identified,
multicast data traffic is forwarded to the multicast router ports. The MFDB is
populated by snooping the membership reports sent to the multicast routers.
This causes multicast data traffic to be forwarded to any hosts joining the
multicast group.

What Is L2 Multicast Traffic?

L3 IP multicast traffic is traffic that is destined to a host group. Host groups
are identified by class D IPv4 addresses, which range from 224.0.1.0 to
239.255.255.255, or by FF0x:: or FF3x:: IPv6 addresses. In contrast to L3
multicast traffic, L2 multicast traffic is identified by the MAC address, i.e.,
the range 01:00:5e:00:00:00 to 01:00:5e:7f:ff:ff:ff for IPv4 multicast traffic or
33:33:xx:xx:xx:xx for IPv6 multicast traffic.
When a packet with a broadcast or multicast destination MAC address is
received, the switch will flood a copy into each of the remaining network
segments in accordance with the IEEE MAC Bridge standard. Eventually, the
packet is made accessible to all nodes connected to the network.
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Configuring L2 Multicast Features