Dual stack IPv6 for IPv4 depletion

Thu Jul 9 01:19:52 UTC 2015

/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 
> 