Application Scenarios for IGMP Snooping

Network Description

In Figure 1, multiple multicast sources, such as Source1 and Source2, exist on a PIM network. The sources provide multicast video services for users on the LAN. HostA and HostC want to receive video data in multicast mode. To prevent multicast data from being broadcast on the LAN, IGMP snooping needs to be configured on the Layer 2 switch to accurately forward multicast data on the Layer 2 network. This prevents bandwidth waste and network information leakage.

Figure 1 IGMP snooping network

Deployed Features

You can deploy the following features to accurately forward multicast data on the network shown in Figure 1:

• PIM and IGMP on the Layer 3 multicast router to route multicast data to user segments.
• IGMP snooping on the Layer 2 switch to set up and maintain a Layer 2 multicast forwarding table, based on which multicast data can be forwarded to specified users.
• IGMP snooping proxy (after configuring IGMP snooping) on the switch to release the router from processing a large number of IGMP messages.
• IGMP snooping SSM mapping on the switch to provide the SSM service for hosts running IGMPv1 or IGMPv2.
  

  Layer 2 SSM mapping must be combined with Layer 3 SSM mapping on the IGMP querier to ensure multicast data forwarding. You must configure Layer 3 SSM mapping entries on the IGMP querier.