Dual stack IPv6 for IPv4 depletion

Thu Jul 9 01:38:49 UTC 2015

What's excessive is >32 bits for a subnet.

No reason subnets should have been as big as they are. Bad for local forwarding decisions, waste of bits, etc.

Nobody has a physical subnet technology that works for more than a few thousand hosts anyway.

Matthew Kaufman

(Sent from my iPhone)

> On Jul 8, 2015, at 6:19 PM, Mike Hammett <nanog at ics-il.net> wrote:
> 
> /56 even seems a bit excessive for a residential user, but *shrugs* 
> 
> 
> 
> 
> ----- 
> Mike Hammett 
> Intelligent Computing Solutions 
> http://www.ics-il.com 
> 
> 
> 
> Midwest Internet Exchange 
> http://www.midwest-ix.com 
> 
> 
> ----- Original Message -----
> 
> From: "Mel Beckman" <mel at beckman.org> 
> To: "Mike Hammett" <nanog at ics-il.net> 
> Cc: "NANOG" <nanog at nanog.org> 
> Sent: Wednesday, July 8, 2015 8:11:05 PM 
> Subject: Re: Dual stack IPv6 for IPv4 depletion 
> 
> Yes. The v6 allocation standards are simple, but can alarming to old-schoolers who have not really thought through the math. 
> 
> A customer gets a /56, which gives them 256 /64 subnets for their own internal use. That accommodates all except the largest customers, and those have the option of getting a /32, which gives them 4.2 billion /64s. 
> 
> ISPs each get a /32 by default, which supports 16.7 million /56 customers. And, of course, the /32 ISP allocation accommodates 4.2 billion ISPs. 
> 
> I don't see the fear. These are just integers, after all. Nothing is really "going to waste". 
> 
> -mel beckman 
> 
>> On Jul 8, 2015, at 5:58 PM, Mike Hammett <nanog at ics-il.net> wrote: 
>> 
>> Isn't /56 the standard end-user allocation? 
>> 
>> 
>> 
>> 
>> ----- 
>> Mike Hammett 
>> Intelligent Computing Solutions 
>> http://www.ics-il.com 
>> 
>> 
>> 
>> Midwest Internet Exchange 
>> http://www.midwest-ix.com 
>> 
>> 
>> ----- Original Message ----- 
>> 
>> From: "Israel G. Lugo" <israel.lugo at lugosys.com> 
>> To: "Mark Andrews" <marka at isc.org> 
>> Cc: "NANOG" <nanog at nanog.org> 
>> Sent: Wednesday, July 8, 2015 7:45:50 PM 
>> Subject: Re: Dual stack IPv6 for IPv4 depletion 
>> 
>> 
>>>> On 07/09/2015 12:59 AM, Mark Andrews wrote: 
>>>> In message <559DB604.8060901 at lugosys.com>, "Israel G. Lugo" writes: 
>>>> Doesn't seem to make sense at all for the ISP side, though. Standard 
>>>> allocation /32. Giving out /48s. Even if we leave out proper subnet 
>>>> organization and allocate fully densely, that's at most 65,536 subnets. 
>>>> Not a very large ISP.
>>> /32 is not the standard allocation. It is the *minimum* allocation 
>>> for a ISP. ISPs are expected to ask for *more* addresses to meet their 
>>> actual requirements.
>> 
>> Thank you for pointing that out. When speaking of /32 I was referring 
>> specifically to RIPE policy, with which I am more familiar: "Initial 
>> allocation size" for a LIR is /32, extensive to a /29 with minimal 
>> bureaucracy. Perhaps I should have said "default allocation". 
>> 
>> I understand ISPs should ask for more addresses; however, even e.g. a 
>> /24 (8x /32) seems to me like it could be "roomier". 
>> 
>> 
>>>> People usually look at IPv6 and focus on the vast numbers of individual 
>>>> addresses. Naysayers usually get shot down with some quote mentioning 
>>>> the number of atoms in the universe or some such. Personally, I think 
>>>> that's a red herring; the real problem is subnets. At this rate I 
>>>> believe subnets will become the scarce resource sooner or later.
>>> No. People look at /48's for sites. 35,184,372,088,832 /48 sites out of the 
>>> 1/8th of the total IPv6 space currently in use. That is 35 trillion sites 
>>> and if we use that up we can look at using a different default size in the 
>>> next 1/8th.
>> Yes, if we look at end sites individually. My hypothesis is that these 
>> astronomic numbers are in fact misleading. There isn't, after all, one 
>> single ISP-Of-The-World, with The-One-Big-Router. 
>> 
>> We must divide the addresses by ISPs/LIRs, and so on. Several bits in 
>> the prefix must be used for subaddressing. A larger ISP will probably 
>> want to further subdivide its addressing by region, and so on. With 
>> subdivisions comes "waste". Which is something we don't need to worry 
>> about at the LAN level, but it would be nice to have that level of 
>> comfort at the subaddressing level as well. 
>> 
>> Let's say I'm a national ISP, using 2001:db8::/32. I divide it like so: 
>> 
>> - I reserve 1 bit for future allocation schemes, leaving me a /33; 
>> - 2 bits for network type (infrastructure, residential, business, LTE): /35 
>> - 3 bits for geographic region, state, whatever: /38 
>> - 5 bits for PoP, or city: /43 
>> 
>> This leaves me 5 bits for end sites: no joy. 
>> 
>> Granted, this is just a silly example, and I don't have to divide my 
>> address space like this. In fact, I really can't, unless I want to have 
>> more than 32 customers per city. But I don't think it's a very 
>> far-fetched example. 
>> 
>> Perhaps I'm missing something obvious here, but it seems to me that it 
>> would've been nice to have these kinds of possibilities, and more. It 
>> seems counterintuitive, especially given the "IPv6 way of thinking" 
>> which is normally encouraged: "stop counting beans, this isn't IPv4". 
>> 
>> Regards, 
>> Israel G. Lugo
> 