Question about IPAM tools for v6

Sam Wilson Sam.Wilson at
Mon Feb 3 12:32:40 CET 2014

On 3 Feb 2014, at 11:17, Nick Hilliard <nick at> wrote:

> On 03/02/2014 11:11, Sam Wilson wrote:
>> Let me de-lurk and make the obvious point that using standard Ethernet
>> addressing would limit the number of nodes on a single link to 2^47, and
>> that would require every unicast address assigned to every possible
>> vendor.  Using just the Locally Administered addresses would limit you
>> to 2^46.
> it bothers me that I can't find any switch with 2^46 ports.
> Damned vendors.

The back of my envelope says that with my vendor of choice and a 4-deep tree (7-hop old-style STP limit) of 384-port switches I can't get more than about 2^34 edge ports.  Very disappointing.  That would need approximately 57 million routers, though, and 170 GW of electrical power, not counting the cooling requirements.  

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

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

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