About IPv6 PIM snooping

IPv6 PIM snooping runs on Layer 2 devices. It works with MLD snooping to analyze received IPv6 PIM messages, and adds the ports that are interested in specific multicast data to an IPv6 PIM snooping routing entry. In this way, the multicast data can be forwarded to only the ports that are interested in the data.

As shown in Figure 89, Source 1 sends multicast data to multicast group G1, and Source 2 sends multicast data to multicast group G2. Receiver 1 belongs to G1, and Receiver 2 belongs to G2. The Layer 2 switch's interfaces that connect to the IPv6 PIM-capable routers are in the same VLAN.

• When the Layer 2 switch only runs MLD snooping, it performs the following actions:

  1. Maintains the router ports according to the received IPv6 PIM hello messages that IPv6 PIM-capable routers send.

  2. Floods all other types of received IPv6 PIM messages except PIM hello messages in the VLAN.

  3. Forwards all multicast data to all router ports in the VLAN.

     Each IPv6 PIM-capable router in the VLAN, whether interested in the multicast data or not, can receive all multicast data and all IPv6 PIM messages except IPv6 PIM hello messages.

• When the Layer 2 switch runs both MLD snooping and IPv6 PIM snooping, it performs the following actions:

  1. Examines whether an IPv6 PIM router is interested in the multicast data destined for a multicast group according to the received IPv6 PIM messages that the router sends.

  2. Adds only the ports that connect to the router and are interested in the data to an IPv6 PIM snooping routing entry.

  3. Forwards IPv6 PIM messages and the multicast data only to the router according to the multicast forwarding entry, which saves network bandwidth.

For more information about MLD snooping and the router port, see "Configuring MLD snooping."

IPv6 PIM snooping can run in IPv6 PIM-SM and IPv6 PIM-SSM networks. Do not configure IPv6 PIM snooping in IPv6 PIM-DM or IPv6 BIDIR-PIM networks. For more information about IPv6 PIM, see "Configuring IPv6 PIM."