Brocade FastIron Ethernet Switch IP Multicast Configuration Guide - Manual (Page 65)

Notice that the receiver for group ff1e::3:4 is directly connected to the device. As a result, the device
does not see a join message on behalf of the client. However, because MLD snooping also is enabled,
the device uses the MLD group membership report from the client to select the port for forwarding traffic
to group ff1e::3:4 receivers.
The MLD snooping feature and the PIM6 SM traffic snooping feature together build a list of groups and
forwarding ports for the VLAN. The list includes PIM6 SM groups learned through join messages as well
as MAC addresses learned through MLD group membership reports. In this case, even though the
device never sees a join message for the receiver for group ff1e::3:4, the device nonetheless learns
about the receiver and forwards group traffic to the receiver.
The device stops forwarding IP multicast traffic on a port for a group if the port receives a prune
message for the group.
Notice that the ports connected to the source and the receivers are all in the same port-based VLAN on
the device. This is required for the PIM6 SM snooping feature. The devices on the edge of the Global
Ethernet cloud are configured for MLD snooping and PIM6 SM traffic snooping. Although this
application uses multiple devices, the feature has the same requirements and works the same way as it
does on a single device.
The following figure shows another example application for PIM6 SM traffic snooping. This example
shows devices on the edge of a Global Ethernet cloud (a Layer 2 Packet over SONET cloud). Assume
that each device is attached to numerous other devices such as other Layer 2 Switches and Layer 3
Switches (routers).
IPv6 Multicast Traffic Reduction
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