[181980] in North American Network Operators' Group
Re: Dual stack IPv6 for IPv4 depletion
daemon@ATHENA.MIT.EDU (Matthew Kaufman)
Thu Jul 9 04:19:09 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <1329877493.3.1436404823201.JavaMail.mhammett@ThunderFuck>
From: Matthew Kaufman <matthew@matthew.at>
Date: Wed, 8 Jul 2015 18:38:49 -0700
To: Mike Hammett <nanog@ics-il.net>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
What's excessive is >32 bits for a subnet.
No reason subnets should have been as big as they are. Bad for local forward=
ing decisions, waste of bits, etc.
Nobody has a physical subnet technology that works for more than a few thous=
and hosts anyway.
Matthew Kaufman
(Sent from my iPhone)
> On Jul 8, 2015, at 6:19 PM, Mike Hammett <nanog@ics-il.net> wrote:
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> /56 even seems a bit excessive for a residential user, but *shrugs*=20
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> -----=20
> Mike Hammett=20
> Intelligent Computing Solutions=20
> http://www.ics-il.com=20
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> Midwest Internet Exchange=20
> http://www.midwest-ix.com=20
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> ----- Original Message -----
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> From: "Mel Beckman" <mel@beckman.org>=20
> To: "Mike Hammett" <nanog@ics-il.net>=20
> Cc: "NANOG" <nanog@nanog.org>=20
> Sent: Wednesday, July 8, 2015 8:11:05 PM=20
> Subject: Re: Dual stack IPv6 for IPv4 depletion=20
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> Yes. The v6 allocation standards are simple, but can alarming to old-schoo=
lers who have not really thought through the math.=20
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> A customer gets a /56, which gives them 256 /64 subnets for their own inte=
rnal use. That accommodates all except the largest customers, and those have=
the option of getting a /32, which gives them 4.2 billion /64s.=20
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> 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.=20
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> I don't see the fear. These are just integers, after all. Nothing is reall=
y "going to waste".=20
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> -mel beckman=20
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>> On Jul 8, 2015, at 5:58 PM, Mike Hammett <nanog@ics-il.net> wrote:=20
>>=20
>> Isn't /56 the standard end-user allocation?=20
>>=20
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>> -----=20
>> Mike Hammett=20
>> Intelligent Computing Solutions=20
>> http://www.ics-il.com=20
>>=20
>>=20
>>=20
>> Midwest Internet Exchange=20
>> http://www.midwest-ix.com=20
>>=20
>>=20
>> ----- Original Message -----=20
>>=20
>> From: "Israel G. Lugo" <israel.lugo@lugosys.com>=20
>> To: "Mark Andrews" <marka@isc.org>=20
>> Cc: "NANOG" <nanog@nanog.org>=20
>> Sent: Wednesday, July 8, 2015 7:45:50 PM=20
>> Subject: Re: Dual stack IPv6 for IPv4 depletion=20
>>=20
>>=20
>>>> On 07/09/2015 12:59 AM, Mark Andrews wrote:=20
>>>> In message <559DB604.8060901@lugosys.com>, "Israel G. Lugo" writes:=20
>>>> Doesn't seem to make sense at all for the ISP side, though. Standard=20=
>>>> allocation /32. Giving out /48s. Even if we leave out proper subnet=20
>>>> organization and allocate fully densely, that's at most 65,536 subnets.=
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>>>> Not a very large ISP.
>>> /32 is not the standard allocation. It is the *minimum* allocation=20
>>> for a ISP. ISPs are expected to ask for *more* addresses to meet their=20=
>>> actual requirements.
>>=20
>> Thank you for pointing that out. When speaking of /32 I was referring=20
>> specifically to RIPE policy, with which I am more familiar: "Initial=20
>> allocation size" for a LIR is /32, extensive to a /29 with minimal=20
>> bureaucracy. Perhaps I should have said "default allocation".=20
>>=20
>> I understand ISPs should ask for more addresses; however, even e.g. a=20
>> /24 (8x /32) seems to me like it could be "roomier".=20
>>=20
>>=20
>>>> People usually look at IPv6 and focus on the vast numbers of individual=
=20
>>>> addresses. Naysayers usually get shot down with some quote mentioning=20=
>>>> the number of atoms in the universe or some such. Personally, I think=20=
>>>> that's a red herring; the real problem is subnets. At this rate I=20
>>>> 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 t=
he=20
>>> 1/8th of the total IPv6 space currently in use. That is 35 trillion site=
s=20
>>> and if we use that up we can look at using a different default size in t=
he=20
>>> next 1/8th.
>> Yes, if we look at end sites individually. My hypothesis is that these=20=
>> astronomic numbers are in fact misleading. There isn't, after all, one=20=
>> single ISP-Of-The-World, with The-One-Big-Router.=20
>>=20
>> We must divide the addresses by ISPs/LIRs, and so on. Several bits in=20
>> the prefix must be used for subaddressing. A larger ISP will probably=20
>> want to further subdivide its addressing by region, and so on. With=20
>> subdivisions comes "waste". Which is something we don't need to worry=20
>> about at the LAN level, but it would be nice to have that level of=20
>> comfort at the subaddressing level as well.=20
>>=20
>> Let's say I'm a national ISP, using 2001:db8::/32. I divide it like so:=20=
>>=20
>> - I reserve 1 bit for future allocation schemes, leaving me a /33;=20
>> - 2 bits for network type (infrastructure, residential, business, LTE): /=
35=20
>> - 3 bits for geographic region, state, whatever: /38=20
>> - 5 bits for PoP, or city: /43=20
>>=20
>> This leaves me 5 bits for end sites: no joy.=20
>>=20
>> Granted, this is just a silly example, and I don't have to divide my=20
>> address space like this. In fact, I really can't, unless I want to have=20=
>> more than 32 customers per city. But I don't think it's a very=20
>> far-fetched example.=20
>>=20
>> Perhaps I'm missing something obvious here, but it seems to me that it=20=
>> would've been nice to have these kinds of possibilities, and more. It=20
>> seems counterintuitive, especially given the "IPv6 way of thinking"=20
>> which is normally encouraged: "stop counting beans, this isn't IPv4".=20
>>=20
>> Regards,=20
>> Israel G. Lugo
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