If hosts' IGMP version can be upgraded to IGMPv1 or IGMPv2, not to IGMPv3, configure Source-Specific Multicast (SSM) mapping to implement version compatibility between a multicast device (running a higher IGMP version) and user hosts (running lower IGMP versions) and enable the multicast device to provide SSM services for the user hosts. The user hosts can then receive multicast data from a specified source.
If a multicast device has many IGMPv1 and IGMPv2 users and there are many SSM mappings, you can configure the DNS-based SSM mapping function to simplify mapping configuration and maintenance.
This section provides an example for configuring dual-device IGMP hot backup in a master/backup E-Trunk scenario. After dual-device IGMP hot backup is configured, multicast services are not interrupted during a master/backup E-Trunk switchover.