Realistic number of hosts for a /64 subnet?

Bernd Walter ticso at
Fri May 10 23:19:50 CEST 2019

On Fri, May 10, 2019 at 10:29:44AM -0700, Joe Hamelin wrote:
> Mark Tinka mentioned:
> >Whether a single LAN can scale to the number of devices a /64 can
> >maximally support... I don't think so, but I also don't know of anyone
> >who has tried.
> Since the MAC address space is 48 bits I would thing that would be the max.

47 bits, as one is reseverved for multiple receivers (broadcast, multicast).
Devices with that bit set in their MAC are calling for troubles.
But only true for ethernet.
IEEE802.15.4 has 64 bit MAC and is used in 6LoWPAN.

B.Walter <bernd at>
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.

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