> On Dec 28, 2017, at 14:31, Thomas Bellman <bell...@nsc.liu.se> wrote: > >> On 2017-12-28 22:31, Owen DeLong wrote: >> >> Sure, but that’s intended in the design of IPv6. There’s really no need >> to think beyond 2^64 because the intent is that a /64 is a single subnet >> no matter how many or how few machines you want to put on it. > >> Before anyone rolls out the argument about the waste of a /64 for a point >> to point link with two hosts on it, please consider that the relative >> difference in waste between a /64 with 10,000 hosts on it and a /64 with >> 2 hosts on it is less than the rounding error in claiming that a /64 is >> roughly 18 quintillion addresses. In fact, it’s orders of magnitude less. > > [...] > >> We may, someday, wish we had gone to some value of N larger than 128, >> but I seriously doubt it will occur in my lifetime. > > My problem with the IPv6 addressing scheme is not the waste of 64 bits > for the interface identifier, but the lack of bits for the subnet id. > 16 bits (as you normally get a /48) is not much for a semi-large organi- > zation, and will force many to have a dense address plan, handing out > just one or a few subnets at a time, resulting in a patch-work of > allocations. 24 bits for subnet id would be more usable.
That’s absurd. The intent is a /48 per end SITE. Not per organization. According to ARIN policies, the definition of an end site is a single building or structure or a single tenant within a multi-tenant building or structure. With nibble boundary round-up in policy, an organization with more than one site can get at least 16 /48s. Further, a university could (technically) get a /48 for every dorm room. > > Consider e.g. a university or company campus. There are probably at > least 16 departments, so I would like to use 8 bits as department id. > Several departments are likely to have offices on more than one floor, > or in more than one building, so I would like to let them have 4 bits > to specify location, and then 8 bits to specify office/workplace within > each location. And allow them to hand out 16 subnets per workplace. > That adds up to 24 bits. So a /40 would be nice, not a /48. A campus is, by definition multiple end sites. > > Similarly, an ISP that wants a structured address plan, e.g. to encode > prefecture, city and part of city in the address, will quickly use up > bits in the customer id part of the address. > An ISP can qualify for up to a /12 in a single allocation. They get two levels of hierarchy at which they can aggregate and do a nibble-boundary round-up. As such, I’m not sure how many bits you want for that that you feel you can’t have. Remember, /32 is just the default no questions asked minimum v6 isp allocation. Not the maximum. I know of at least three isps that have /24s or more of ipv6 space. > > /Bellman > Owen
