Application Examples of PIM6 SM Traffic Snooping

The following figure shows an example application of the PIM6 SM traffic snooping feature. In this example, a device is connected through an IP router to a PIM6 SM group source that is sending traffic for two PIM6 SM groups. The device also is connected to a receiver for each of the groups.

When PIM6 SM traffic snooping is enabled, the device starts listening for PIM6 SM join and prune messages and MLD group membership reports. Once the device receives a join message or group membership report for a group, the device forwards subsequent traffic for that group only on the ports from which the join messages or MLD reports were received.

In this example, the router connected to the receiver for group ff1e::1:2 sends a join message toward the group source. Because PIM6 SM traffic snooping is enabled on the device, the device examines the join message to learn the group ID, then makes a forwarding entry for the group ID and the port connected to the receiver router. The next time the device receives traffic for ff1e::1:2 from the group source, the device forwards the traffic only on port 1/5/1, because that is the only port connected to a receiver for the group.

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.

Note: This example assumes that the devices are actually Ruckus devices running Layer 2 Switch software.
Figure 1. PIM6 SM Traffic Reduction in Global Ethernet Environment

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.