nanog mailing list archives
Re: Waste will kill ipv6 too
From: Mark Andrews <marka () isc org>
Date: Fri, 29 Dec 2017 09:52:59 +1100
On 29 Dec 2017, at 9:31 am, Thomas Bellman <bellman () 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.
What’s wrong with a dense allocation? That’s what we have routers for. Thats why we have a protocol for prefix delegation. You can do on demand subnet allocation without involving humans.
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.
Stop with the IPv4 think. This is all driven by humans allocating addresses. Use the features of IPv6. You have on demand prefix allocation. you have ULA addresses where every student can have their own /48 play space by randomly selecting a ULA /48 prefix.
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. /Bellman
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka () isc org
Current thread:
- Re: Waste will kill ipv6 too, (continued)
- Re: Waste will kill ipv6 too Lyndon Nerenberg (Dec 28)
- Re: Waste will kill ipv6 too Brock Tice (Dec 28)
- Re: Waste will kill ipv6 too Lyndon Nerenberg (Dec 28)
- Re: Waste will kill ipv6 too valdis . kletnieks (Dec 28)
- Re: Waste will kill ipv6 too Mark Andrews (Dec 28)
- Re: Waste will kill ipv6 too valdis . kletnieks (Dec 28)
- Re: Waste will kill ipv6 too Mark Andrews (Dec 28)
- Re: Waste will kill ipv6 too Owen DeLong (Dec 28)
- Re: Waste will kill ipv6 too Lyndon Nerenberg (Dec 28)
- Re: Waste will kill ipv6 too Ricky Beam (Dec 28)
- Re: Waste will kill ipv6 too Mark Andrews (Dec 28)
- Re: Waste will kill ipv6 too Owen DeLong (Dec 28)
- Re: Waste will kill ipv6 too bzs (Dec 28)
- Re: Waste will kill ipv6 too Owen DeLong (Dec 28)
- Re: Waste will kill ipv6 too bzs (Dec 28)
- Re: Waste will kill ipv6 too Large Hadron Collider (Dec 28)
- Re: Waste will kill ipv6 too valdis . kletnieks (Dec 28)
- Re: Waste will kill ipv6 too sthaug (Dec 29)
- Re: Waste will kill ipv6 too Mikael Abrahamsson (Dec 29)
- Re: Waste will kill ipv6 too Nick Hilliard (Dec 29)
- Re: Waste will kill ipv6 too Owen DeLong (Dec 29)