[Re: http://tools.ietf.org/search/draft-hain-ipv6-ulac-01]

Mon Apr 26 15:01:37 UTC 2010

On Apr 26, 2010, at 5:27 AM, Tony Hoyle wrote:

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> On 26/04/2010 08:08, Mark Smith wrote:
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>> 
>>> How much do you understand about IPv6 addressing? Are you aware that
>>> IPv6 addresses have explicit preferred and valid lifetimes, and
>>> therefore they can change over time?
> 
> Only via privacy extensions.. and I always switch them off as they're a
> pain in the neck.  Even with those they don't change the prefix.
> 
Uh, no... If you're using slack, IPv6 addresses have explicit preferred and valid
lifetimes for the PREFIX which can change over time at the decision of the
person running the device(s) issuing the RAs.

> My /48 is allocated to me..  In no sane world would that suddenly
> change, unless I did something major like change ISP, any more than my
> v4 address would suddenly change.
> 
Agreed, mostly.  If your provider issues your /48 to you via DHCP-PD, then,
it, too, has a desired and valid lifetime which is expected to be passed along
in your subordinate RAs, and, it means that if they reconfigure their DHCP
server, you are expected to abide by the change.

> You're trying to say ipv6 prefixes change randomly over time - just
> think of the implications if that could happen... even basic things like
> firewalling would become a nightmare.
> 
Whether they do or not depends on your circumstance and the design
of upstream networks. They may or may not. Certainly it is desirable
from a customer perspective that they do not. It may be equally desirable
from a carrier perspective that they do. Personally, I hope carriers will
design their networks well enough that changing prefixes at random
times is not necessary and customers can get a better IPv6 experience.

We, for one, use static assignments at HE.

Owen