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 <na...@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" <m...@beckman.org> > To: "Mike Hammett" <na...@ics-il.net> > Cc: "NANOG" <nanog@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 <na...@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.l...@lugosys.com> >> To: "Mark Andrews" <ma...@isc.org> >> Cc: "NANOG" <nanog@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 <559db604.8060...@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 >
