664 BigIron RX Series Configuration Guide53-1002253-01Configuring IP multicast traffic reduction23Notice that the ports connected to the source and the receivers are all in the same port-basedVLAN on the device. This is required for the PIM SM snooping feature. The feature also requiresthe source and the downstream router to be on different IP subnets, as shown in Figure 99.Figure 100 shows another example application for PIM SM traffic snooping. This example showsdevices on the edge of a Global Ethernet cloud (a Layer 2 Packet over SONET cloud). Assume thateach device is attached to numerous other devices such as other BigIron RXs.FIGURE 100 PIM SM traffic reduction in global Ethernet environmentThe devices on the edge of the Global Ethernet cloud are configured for IP multicast trafficreduction and PIM SM traffic snooping. Although this application uses multiple devices, thefeature has the same requirements and works the same way as it does on a single device.Configuration requirements• IP multicast traffic reduction must be enabled on the device that will be running PIM SMsnooping. The PIM SM traffic snooping feature requires IP multicast traffic reduction.NOTEUse the passive mode of IP multicast traffic reduction instead of the active mode. The passivemode assumes that a router is sending group membership queries as well as join and prunemessages on behalf of receivers. The active mode configures the device to send groupmembership queries.• All the device ports connected to the source and receivers or routers must be in the sameport-based VLAN.Switch ASwitch B Switch CVLAN 2Port5/1 VLAN 2Port7/1VLAN 2Port1/1VLAN 2Port5/1VLAN 2Port1/1VLAN 2Port1/1VLAN 2Port5/1Receiver for Group239.255.162.69Client sends anIGMP groupmembership reportfor 239.255.162.69.Receiver for Group239.255.162.1Router sends aPIM SM join messagefor 239.255.162.1. RouterClientClientRouterClient10.10.10.5The switches “snoop” for PIM SMjoin and prune messages.Switch A detects a source on port1/1and a receiver for that source’s groupon port5/1. The switch forwardsmulticast data from the source on port1/1out port5/1 only, which has the receiver.Without PIM SM traffic snooping, theswitch would forward traffic from thesource out all other ports.20.20.20.5Source for Groups239.255.162.1239.255.162.69
