Realistic number of hosts for a /64 subnet?

WILSON Sam sam.wilson at
Tue May 14 11:10:55 CEST 2019

> On 13 May 2019, at 06:20, Philip Loenneker <Philip.Loenneker at> wrote:
> To be sure, you could always put your phone system on the same network segment too...
> Back to the original discussion, it's worth keeping in mind that individual devices can and do have multiple IPv6 addresses, so the IPv6 utilisation vs the number of devices on the layer 2 segment could vary significantly. So if you want to know how many devices are actually on a network segment, you would want to check MAC address tables or filter for unique MAC addresses within the ARP table rather than a ping sweep or similar.

Except those nasty security people are now allowing systems to randomise their MAC addresses.  I'm sure some people's Life Goal is to make life as difficult as possible for us network operators.


Sam Wilson
Communications Infrastructure Services, IT Infrastructure
Information Services, The University of Edinburgh
Edinburgh, Scotland, UK

As of Monday 1 October 2018 I will be working 2 days per week, Tuesday and Thursday but with some flexibility as required.

The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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