Re: IPv6 /64 links (was Re: ipv6 book recommendations?)

["Dale W. Carder" <dwcarder () wisc edu>]

Thus spake Chuck Church (chuckchurch () gmail com) on Wed, Jun 06, 2012 at 10:58:05AM -0400:
> Does anyone know the reason /64 was proposed as the size for all L2 domains?

Some day eui-48 will "run out".  So, just assume eui-64 now and map into it.

Also, as you point out below, not all L2 is ethernet.

> I've looked for this answer before, never found a good one.  I thought I
> read there are some L2 technologies that use a 64 bit hardware address,
> might have been Bluetooth.  Guaranteeing that ALL possible hosts could live
> together in the same L2 domain seems like overkill, even for this group.
> /80 would make more sense, it does match up with Ethernet MACs.  Not as easy
> to compute, for humans nor processors that like things in 32 or 64 bit
> chunks however.  Anyone have a definite answer?

A good history lesson for this addressing model would be to look at IPX.
(And maybe also IRDP for ipv4).  When we did our first trial ipv6
deployments here in the early 2000's we were still running IPX, so I guess
SLAAC wasn't hard to grasp.

Dale