Re: IPv6 fc00::/7 — Unique local addresses

Thu Oct 21 00:07:57 UTC 2010

On Wed, Oct 20, 2010 at 4:48 PM, Jeroen van Aart <jeroen at mompl.net> wrote:
> <IPv6 newbie>

> these addresses, their address scope is global, i.e. they are expected to be
> globally unique."

The ULA /48s are hoped to only be globally unique,  but this only has
a good chance of happening
if   all users  pick good random numbers as required,   which will
often be 'hard to read'.
should any two networks pick non-random numbers,  they could easily
conflict,  breaking expectations.

My suspicion is that in the future it is going to happen routinely,
esp.   if  ULA  becomes to  IPv6  what
RFC1918 space is to IPv4,   with  most end user networks implementing
 NAT66  to translate  "private"
/48 ULAs   to their site's  "public"    /48    assignment from their ISP.

I can imagine generic $50  IPv6 broadband routers   getting
distributed en-masse that hardcode  all bits 0
ULA NAT66 by default, and expect the user to change the LAN IP subnet
/ NAT config  from the defaults,
sometime while they're setting it up,  probably at the same time they
change the admin password.

You know... the type of router a residential user plugs in, and they
"just work",
and if the user forgets to follow any setup or config directions,
just pulls an IP via DHCP and
sticks with some insecure defaults.

But it would still be a big improvement from what is available with V4.
--
-Jh