IPv6 Addressing Help

Jeroen Massar jeroen at unfix.org
Fri Aug 14 13:40:06 CDT 2009

William Herrin wrote:
> I'm not aware of any way of dynamically assigning an IPv6 subnet to a
> customer that's as well automated as IPv4 /32 dynamic assignment to a
> DSL router with an RFC1918 NATed interior, but that may just be my
> ignorance since I haven't needed to research it.

DHCP-PD (prefix delegation)

> Static IP customer: /60

ARIN defines a /56 minimum. That is the reason that ISPs get a /32.
RIPE defines a /48 at the moment.

> I recommend /60 as the customer default where most folks suggest /56
> or /48. The IPv6 use profile looks a heck of a lot like the IPv4 use
> profile and /60 is 16 subnets. How many of your customers find a
> reason to use more than 3 IPv4 subnets, including their RFC1918 ones?
> Relatively few.

Think Future. And why bother with that anyway. If you as an ISP needs
more address space just ring RIPE/ARIN/APNIC and ask for more, they will
happily give it to you.

> Giving every customer enough subnets by default to meet 90% of the
> typical usage profiles is not the worst idea in the world... IMHO it's
> a pretty bright idea. But there's no need to be damnfool wasteful
> about it.

I guess you ran the numbers on how to run out of IPv6 address space?

You can always ask the US DoD for a few /32s, they have enough of them...

Routing will become a problem before IPv6 address space will run out.
Oh, and we are only allocating from 2000::/3 at the moment, can retry on
the other 7 /8s....


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