Some advice on IPv6 planning and ARIN request, please

Thomas Bellman bellman at nsc.liu.se
Mon Jul 10 09:33:03 UTC 2017


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On 2017-07-08 23:00, Radu-Adrian Feurdean wrote:

> On Sat, Jul 8, 2017, at 19:13, Mel Beckman wrote:

>> That open atmosphere was by design. It's why IPv6 uses 128-bit addresses,
> 
> That's for hosts. When you care more about subnets, it's shortened to 64
> bits.

Indeed.  Especielly if you do hierarchical delegation within your
organization, you will often have sparse allocations at several
levels.  A /48 for an organization might seem like reasonably lots
with 65536 subnets, but if that organization in turn delegates to
departments, and they have more than 16 departments, each department
might only get a /56 (256 subnets).  Try to delegate that one step
further, and you can't do any reasonable allocation strategy, but
have to allocate subnet by subnet.

I managed to get a full /52 from our host university, but they
initially wanted to give us only a /56.  Of course, they can only
give out a few /52:s; other departments will have less structured
address plans than us.


- -- 
Thomas Bellman,  National Supercomputer Centre,  Linköping Univ., Sweden
"Life IS pain, highness.  Anyone who tells   !  bellman @ nsc . liu . se
 differently is selling something."          !  Make Love -- Nicht Wahr!

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