In a PPPoE environment, multicast replication is performed per session (host) regardless of whether those sessions are shared per SAP or they reside on individual SAPs. This is because of the point-to-point nature of PPPoE sessions. HQoS adjustment is not needed as multicast is part of the PPPoE session traffic that is flowing through subscriber queues. Multicast packets are sent with unicast MAC address to each CPE. PPP protocol field is set to IP and the destination IP address is the multicast group address for each unique session ID.
This model is shown in Figure: Multicast IPv4 address and unicast MAC address in PPPoE subscriber multicast.
Note that in a SRRP setup, the multi-chassis active BNG (SRRP master state) uses the SRRP MAC address as the source MAC for both multicast and multicast control protocol packets. This is only applicable to PPPoE hosts.