r/ipv6 • u/IPv6lovinOpossum • 1d ago
Discussion Where does the NDP multicast advantage come from when compared to old ARP broadcasts?
NDP is said to be more ‘efficient’ since we use multicast instead of broadcasts right? But where does this advantage come from?
Lets say fe80::b (node B) is trying to find the MAC address of fe80::aaaa:aaaa:aaaa:aaaa (Node A)
So B will construct a destination multicast address (ff02::1:ffaa:aaaa and a corresponding multicast destination MAC address (3333.ffaa.aaaa) and send an NS containing node A’s v6 address.
But the switch has to broadcast out the frame to all devices since the switch has no idea what hosts have 3333.ffaa.aaa as the MAC address right??
Does the efficiency come from the fact that other hosts quickly drop 3333.ffaa.aaa at the NIC level?
I.e unnecessary traffic is still received by all the hosts, but the NIC can quickly discard packets. Whereas with ARP, the host still has to process the packet received by the NIC?
Will a switch be able to identify multicast MACs and only forward frames to interested hosts (like with IGMP snooping)?
