[ppml] /48 vs /32 micro allocations

Kevin Loch kloch at hotnic.net
Tue Mar 15 12:15:51 EST 2005

bmanning at vacation.karoshi.com wrote:
> 		) there will be enough IPv6 space to last for the next
> 		  30 years

Increasing the minimum allocation size for a few hundred micro
allocations to 1 / 4billionth of the total address space is not
wasteful. If you are concerned with relative waste you might want
to look at the HD ratio of 0.8 (!) that is resulting in /19 allocations
(that's 8192 /32's right there).

> 		) no one would -ever- dare treat IPv6 space as anything
> 		  useful in less than /32 chunks

This isn't about /33-/47 it's about /48 (see below).

> 		) no harm will insue if folks advertise routes to space
> 	    	  that has no endsystem attached.

Others have addressed authentication but I think maintaining the MRU
above /48 would help. The larger prefix an abuser has to announce the
more likely it is to be noticed.  The presense of end systems doesn't
help at all in IPv6 (host density is impossibly low) though I can see
problems if the micro allocation is larger than the effective MRU
(abuser announces more specifics). There's nothing to stop you from
announcing the more specifics yourself, at least then the larger RIR
allocation won't encourage looser filters.  If /32 micro allocations are
so harmful, then why is that the policy of the other RIR's?  K, I and M
root all have /32's allocated.

> 		) we understand all there is to know about how applications
> 		  and services will develop over the next two decades to
> 		  presume a steady, consistant "burn-rate" of space.

Right now we are talking about a few hundred micro allocations.  When
(not if) we start talking about end site allocations we could consider
smaller sizes than /32 but even then not /48 unless the intent is that
all /48's (directly assigned or not) be globally routable.

> 		) no fundamental technological changes will occur on our
> 		  watch and if it does, it can be solved by new talent.
> 		) that the IETF leaves routing development alone.

Allocation policy is not set in stone.  RIR's can and do change policy
as conditions change.  What is the right thing to do right now?

> 	If this is the basis of your argument, then i'll agree that its 
> 	a good proposal, if all my points are accepted and ISPs agree to
> 	never announce anything smaller than what there RIR gives them.

Of course they will.  I'm not suggesting we could maintain an MRU of
/32.  With the quantumn nature of current address quidelines, there is
all the difference in the world between an MRU of /48 and /47.

Would you agree that:

- There is a benefit to increasing micro allocations above /48 WRT MRU
- There is some value between /32 and /47 where the benefits outweigh
the risks?

Considering that allocation policy can always be revised in the future.
(we're only talking about critical infrastructure at this point).


More information about the ARIN-PPML mailing list