On Wed, Dec 4, 2013 at 1:32 PM, Rob Seastrom <r...@seastrom.com> wrote: > > Brian Dickson <brian.peter.dick...@gmail.com> writes: > >> Rob Seastrom wrote: >> >>> "Ricky Beam" <jfbeam at >>> gmail.com<http://mailman.nanog.org/mailman/listinfo/nanog>> >>> writes: >>> > >>> * On Fri, 29 Nov 2013 08:39:59 -0500, Rob Seastrom <rs at seastrom.com >>> <http://mailman.nanog.org/mailman/listinfo/nanog>> wrote: *>> >>> * So there really is no excuse on AT&T's part for the /60s on uverse >>> 6rd... *> >>> * ... *> >>> * Handing out /56's like Pez is just wasting address space -- someone *> >>> * *is* paying for that space. Yes, it's waste; giving everyone 256 *> >>> * networks when they're only ever likely to use one or two (or maybe *> >>> * four), is intentionally wasting space you could've assigned to *> >>> * someone else. (or **sold** to someone else :-)) IPv6 may be huge to *> >>> * the power of huge, but it's still finite. People like you are *> >>> * repeating the same mistakes from the early days of IPv4... * There's >>> finite, and then there's finite. Please complete the >>> following math assignment so as to calibrate your perceptions before >>> leveling further allegations of profligate waste. >>> Suppose that every mobile phone on the face of the planet was an "end >>> site" in the classic sense and got a /48 (because miraculously, >>> the mobile providers aren't being stingy). >>> Now give such a phone to every human on the face of the earth. >>> Unfortunately for our conservation efforts, every person with a >>> cell phone is actually the cousin of either Avi Freedman or Vijay >>> Gill, and consequently actually has FIVE cell phones on active >>> plans at any given time. >>> Assume 2:1 overprovisioning of address space because per Cameron >>> Byrne's comments on ARIN 2013-2, the cellular equipment providers >>> can't seem to figure out how to have N+1 or N+2 redundancy rather >>> than 2N redundancy on Home Agent hardware. >>> What percentage of the total available IPv6 space have we burned >>> through in this scenario? Show your work. >>> -r >> >> >> Here's the problem with the math, presuming everyone gets roughly the same >> answer: >> The efficiency (number of prefixes vs total space) is only achieved if >> there is a "flat" network, >> which carries every IPv6 prefix (i.e. that there is no aggregation being >> done). >> >> This means 1:1 router slots (for routes) vs prefixes, globally, or even >> internally on ISP networks. >> >> If any ISP has > 1M customers, oops. So, we need to aggregate. >> >> Basically, the problem space (waste) boils down to the question, "How many >> levels of aggregation are needed"? >> >> If you have variable POP sizes, region sizes, and assign/aggregate towards >> customers topologically, the result is: >> - the need to maintain power-of-2 address block sizes (for aggregation), >> plus >> - the need to aggregate at each level (to keep #prefixes sane) plus >> - asymmetric sizes which don't often end up being just short of the next >> power-of-2 >> - equals (necessarily) low utilization rates >> - i.e. much larger prefixes than would be suggested by "flat" allocation >> from a single pool. >> >> Here's a worked example, for a hypothetical big consumer ISP: >> - 22 POPs with "core" devices >> - each POP has anywhere from 2 to 20 "border" devices (feeding access >> devices) >> - each "border" has 5 to 100 "access" devices >> - each access device has up to 5000 customers >> >> Rounding up each, using max(count-per-level) as the basis, we get: >> 5000->8192 (2^13) >> 100->128 (2^7) >> 20->32 (2^5) >> 22->32 (2^5) >> 5+5+7+13=30 bits of aggregation >> 2^30 of /48 = /18 >> This leaves room for 2^10 such ISPs (a mere 1024), from the current /8. >> A thousand ISPs seems like a lot, but consider this: the ISP we did this >> for, might only have 3M customers. >> Scale this up (horizontally or vertically or both), and it is dangerously >> close to capacity already. >> >> The answer above (worked math) will be unique per ISP. It will also drive >> consumption at the apex, i.e. the size of allocations to ISPs. >> >> And root of the problem was brought into existence by the insistence that >> every network (LAN) must be a /64. >> >> That's my 2 cents/observation. >> >> Brian > > At a glance, I think there's an implicit assumption in your > calculation that each ISP has to be able to hold the whole world > (unlikely) and/or there is no such thing as mobile IP or any other > kind of tunneling technology going on within the mobile network (also > wrong from everything I understand). > > Also, I'm not sure where "from the current /8" comes from, as there's > a /3 in play (1/8 of the total space, maybe that was it?) and each > RIR is getting space in chunks of /12... > > Re-working your conclusion statement without redoing the math, "This > leaves room for 2^15 such ISPs (a mere 16384), from the current /3." > > Oddly enough, I'm OK with that. :)
16384 'isp' which is really 'transit asn' right?
