In article <CAOVYXj-DWX0FhcEJdPMBfec6HcykWtRrErC8wDuBDYYFmE_cWQ@mail.gmail.com> you write:
that gets me on to my small annoyance... /64 bit subnet masks for local networks. really?
Yup.
ALL of that address space and then throw such a large range away on subnets commonly populated with no more than a couple of hundred clients...maybe a few thousand at worst. what a mistake.
Nope. The whole point of 128 bit addresses is that you can waste bits with wild abandon. My upstream originally assigned me a /64 but since I have two network segments, they gave me a /48, of which I am using two /64s. Since they have a /32, they won't run short of /48's until they have 65,000 clients with multi segment networks, which will take a very long time. In the unlikely event that happens, they can upgrade their /32 to a /31, since ARIN allocates the /32's with slop between them. The programming and configuration is much easier since we can always assume that every network will have a /64 and no more and no less.
I come from a background where we had IPv4/DECNET/AppleTalk/IPX all around the place -
Unlike all of them, one mistake that IPv6 did *not* make was to make addresses too short. In the same way, IPv6 ULAs are a lot better than IPv4 RFC1918 space. So long as you follow the spec and pick a truly random ULA prefix, even if your networks later merge with others the chances of ULAs colliding rounds to zero.