[arin-ppml] Draft Policy ARIN-2024-8: Restrict the Largest Initial IPv6 Allocation to /20

[Mark Andrews]

Well that looks like an area of policy that needs to be tightened. 

I dislike IETF’s advice to use 32 bits with /64s and 6rd as there is an incredible amount of wastage.  For /48s its insane wastage.

Even with the disjointed GUA IPv4 address assignments ISPs tend to only have addresses in a few /8s.  6rd can be trivially configured to have a prefix per /8 using 24 bits rather than 32 bits and there would be a small multiple if /24s of IPv6 space used rather than a /16.   Yes the border router would have a slightly more complex configuration if you have multiple pops in multiple /8s using it. 

If you are not using GUAs then you don’t need to use 32 bits as there is no benefit in making it that big as it can’t simplify anything.  10/8 24 bits is the biggest you would go. 100.64/10 is 22 bits.  These are maximum sizes.  You need different IPv6 prefixes per instance anyway. 

-- 
Mark Andrews

> On 28 Jun 2024, at 05:19, William Herrin <bill at herrin.us> wrote:
> 
> On Thu, Jun 27, 2024 at 12:14 PM Mark Andrews <marka at isc.org> wrote:
>> I would argue that it is not needed for 6rd as you can pack
>> things much denser with proper 6rd parameter management.
> 
> Hi Mark,
> 
> Of course it isn't needed for 6rd. That's not the question. The
> question is: does such use technically justify addresses under current
> ARIN policy? The answer, as I understand it, is: yes. If I happen to
> have a couple dozen disjoint IPv4 allocations and I want to simplify
> my 6rd deployment by throwing addresses at it, I have met the
> requirements for an ARIN IPv6 allocation that throws 32 bits at 6rd.
> 
> Regards,
> Bill Herrin
> 
> -- 
> William Herrin
> bill at herrin.us
> https://bill.herrin.us/