Is a /48 still the smallest thing you can route independently?

Owen DeLong owen at delong.com
Thu Oct 11 22:11:09 UTC 2012


On Oct 11, 2012, at 2:17 PM, Jeroen Massar <jeroen at unfix.org> wrote:

> On 2012-10-11 23:02 , Jo Rhett wrote:
>> I've finally convinced $DAYJOB to deploy IPv6.  Justification for the
>> IP space is easy, however the truth is that a /64 is more than we
>> need in all locations. However the last I heard was that you can't
>> effectively announce anything smaller than a /48.  Is this still
>> true?
>> 
>> Is this likely to change in the immediate future, or do I need to ask
>> for a /44?
> 
> A /64 is for a single link (broadcast domain, though with IPv6 multicast
> domain is more appropriate).
> 
> A /48 (or /56 for end-users for some of the RIRs) is for a single
> end-site ("a different administrative domain and/or a different physical
> location").
> 
> If you thus have 5 end-sites, you should have room for 5 /48s and thus a
> /47 is what you can justify.
> 
Couple of errors there, Jeroen…

1. 5 /48s is at least a /45, not a /47 which is only 2 /48s.

2. Joe lives in the ARIN region where allocations and assignments are
	done on nibble boundaries, so his /45 would be rounded up to
	a /44 (as would a /47) anyway.

Owen




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