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

Jeroen Massar jeroen at unfix.org
Thu Oct 11 21:17:40 UTC 2012


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.

If you though are not able to do transit / routing between those sites
as they are not connected one might want to get separate PI /48s for
them. But likely if you are in that camp, just asking for address space,
that you can use stably for a long time, from your network provider who
provides you connectivity is a better way to go.

Greets,
 Jeroen



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