On Thu, Dec 28, 2017 at 7:24 PM, Ricky Beam <jfbeam@gmail.com> wrote:
Back to the main theme... artificially cutting the address space in half, just makes the point even stronger. IPv6 address space is, in fact, half as big as people think it is, because we've drawn a line at /64
Hi Ricky, Your math is a little off. Drawing the line at /64 doesn't cut the address space in half, it shrinks it by roughly 19 orders of magnitude. There are 10^38 IPv6 addresses but only 10^19 IPv6 /64 LANs. -- and the catastrophic part is people *ARE* wiring that into hardware.
Every example I've seen people bat around about just how big 2^128 is, ignores the reality of Real World Networking(tm). They ignore infrastructure. The ignore route table size. They ignore the sparse nature of hierarchical address assignment. In the "10B people === 10B /48's" example, that's a dense PI allocation scheme that will lead to a global routing table approaching 10B routes -- you can't aggregate a random selection of /48s -- with zero consideration for how those 10B networks will interconnect.
The simple truth is, we're doing the exact same thing with IPv6 that we did with IPv4: "The address space is so mind alteringly large we'll never use even a fraction of it." *pause* "Umm, wait a minute, we're carving this turkey up alarmingly fast." Will we use up the entire thing? Of course we will; it's not, in fact, *infinite*, so we *will* eventually assign all of it. It's going to happen a lot faster than most people think, as we're so cavalier with handing out vast amounts of space for which most people will never use more than (a) one LAN, and (b) a few dozen addresses within that single LAN. Will it happen in 5, 10, 100 years? The later is a safer bet. (not that I'll be around to collect) But just like IPv4, some decades down the road, people will see how stupid our allocation scheme really is, and begin a new "classless" era for IPv6. The short of it is, we got here first, so we don't have to give a shit about being efficient or frugal.
Yep. Regards, Bill Herrin -- William Herrin ................ herrin@dirtside.com bill@herrin.us Dirtside Systems ......... Web: <http://www.dirtside.com/>