MAC-based Forwarding Implementation on ICX Devices

Multicast Listening Discovery (MLD) snooping on ICX devices is based on MAC address entries. When an IPv6 multicast data packet is received, the packet destination MAC is matched with the MAC address entries in the IPv6 multicast table. If a match is found, packets are sent to the ports associated with the MAC address. If a match is not found, packets are flooded to the VLAN and copied to the CPU.

For IPv6 multicast, the destination MAC address is in the format 33-33-xx-yy-zz-kk, where xx-yy-zz-kk are the 32 lowest bits of the IPv6 multicast group address. For example, the IPv6 group address 0xFF3E:40:2001:660:3007:123:0034:5678 maps to the IPv6 MAC address 33-33-00-34-56-78.

For two multicast traffic streams, Source_1 and Group1 (S1,G1) and Source_2 and Group2 (S2,G2), with the same or different source addresses, if the lowest 32 bits of the 128-bit IPv6 group address are the same, they would map to the same destination MAC.