IPv6 Ignorance

Owen DeLong owen at delong.com
Mon Sep 17 18:28:56 UTC 2012


On Sep 17, 2012, at 08:16 , Mark Blackman <mark at exonetric.com> wrote:

> 
> On 17 Sep 2012, at 15:55, Adrian Bool <aid at logic.org.uk> wrote:
> 
>> 
>> Hi,
>> 
>> On 17 Sep 2012, at 15:02, Nick Hilliard <nick at foobar.org> wrote:
>>> On 17/09/2012 14:37, Adrian Bool wrote:
>>>> It seems a tad unfair that the bottom 80 bits are squandered away with a
>>>> utilisation rate of something closely approximating  zero
>>> 
>>> You are thinking in ipv4 mode. In ipv6 mode, the consideration is not how
>> 
>>> many hosts you have, but how many subnets you are dealing with.  Instead of
>>> thinking of 128 bits of addressing space, we talk about 64 bits of subnet
>>> space.  So your statement comes down to: "it seems a tad unfair that the
>>> bottom 16 bits are squandered away".  This is a more difficult argument to
>>> make.
>> 
>> I don't really agree with the "IPv6 think" concept - but let's put that aside for now...
>> 
>> The default allocation size from an RIR* to an LIR is a /32.  For an LIR providing /48 site allocations to their customers, they therefore have 16-bits of address space available to them to address their customers.
>> 
>> So, even in "IPv6 think", homes that typically have one subnet have an equal number of bits to address their single subnet as an LIR has to address all of their customers.
>> 
>> It seems illogical to me that we've got an 128-bit address space, featuring numbers far larger than any human can comprehend, yet the default allocation to an LIR allows them to address such a feeble number as 65,536 customers - a number far smaller than the number of customers for medium to large ISPs.
>> 
>> The default LIR allocation should be a several orders of magnitude greater than the typical customer base  - not a smaller default allocation.
> 
> Amen, brother! I was doing that particular computation about six months ago when we had
> our first request and arrived at the same conclusion. I've concluded that /48 for businesses
> and /56 for residential sites is the more reasonable approach until we start getting /24 IPv6
> allocations for LIRs and I think many others have concluded the same.
> 
> - Mark
> 

LIRs which need /24s can get /24s.

/32 was never a maximum, it was merely the minimum and as such is a reasonable starting point.

The vast majority of ISPs in operation today can give all their customers /48s out of a /28 and still have lots of room to spare.
For larger providers, they should have no trouble justifying a much larger block.

I know from experience that it is possible to get /24s in the ARIN region with reasonable justification, for example.

Owen




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