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

Mark Smith nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
Sat Apr 24 21:01:06 CDT 2010

On Thu, 22 Apr 2010 01:48:18 -0400
Christopher Morrow <morrowc.lists at gmail.com> wrote:

> On Wed, Apr 21, 2010 at 5:47 PM, Mark Smith
> <nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org> wrote:
> > On Wed, 21 Apr 2010 09:25:46 -0400
> > Christopher Morrow <morrowc.lists at gmail.com> wrote:
> >
> >> On Wed, Apr 21, 2010 at 1:29 AM, Owen DeLong <owen at delong.com> wrote:
> >> > While I think this is an improvement, unless the distribution of ULA-C is no cheaper
> >> > and no easier to get than GUA, I still think there is reason to believe that it is likely
> >> > ULA-C will become de facto GUA over the long term.
> >> >
> >> > As such, I still think the current draft is a bad idea absent appropriate protections in
> >> > RIR policy.
> >>
> >> I agree with owen, mostly... except I think we should just push RIR's
> >> to make GUA accessible to folks that need ipv6 adress space,
> >> regardless of connectiivty to thegreater 'internet' (for some
> >> definition of that thing).
> >>
> >> ULA of all types causes headaches on hosts, routers, etc. There is no
> >> reason to go down that road, just use GUA (Globally Unique Addresses).
> >>
> >
> > So what happens when you change providers? How are you going to keep
> > using globals that now aren't yours?
> use pi space, request it from your local friendly RIR.

I was hoping that wasn't going to be your answer. So do you expect
every residential customer to get a PI from an RIR?

Here's the scenario:

I'm a typical, fairly near future residential customer. I have a NAS
that I have movies stored on. My ISP delegates an IPv6 prefix to me with
a preferred lifetime of 60 minutes, and a valid lifetime of 90 minutes
(in my personal opinion, thats too small, but it's the ISP's address
space, so I have to accept the lifetimes they give me). I start
watching a 2 hour movie, delivered from my NAS to my TV over IPv6,
using the GUA addresses (because you're saying I don't ULAs). 5 minutes
into the movie, my Internet drops out. 1 hour, 35 minutes into movie,
the movies drops out, because the IPv6 addresses used to deliver it
can't be used anymore. Is that an acceptable customer networking
experience? It won't happen in IPv4, because customers typically have
stable RFC1918 addresses. It is unacceptable that it should happen in
IPv6, yet you can't expect residential customers to pay RIR fees to get
PI address space - and should that even happen, when are we going to
have carrier routers that can route 500 Million (my very much rough
estimate of houses in the world) routes?

The majority of Internet connections are residential. "Enterprise
solutions", like PI and RIR fees, aren't just feasible for the majority
of the Internet.

> > I'm also curious about these headaches. What are they?
> do I use that ula-* address to talk to someone or another GUA address?
> how do I decide? what about to business partners?

That's why there are source address selection rules in IPv6, that
factor in destination address types.

> one address... much simpler, much less to screw up.

I'm all for simplicity. Unfortunately however, to overcome a problem,
you usually have to add something, and adding something usually adds
complexity. The key goal is to minimise the additional complexity as
much as possible, without loosing the benefit.

Networks need stable addressing, that is independent of the address
space their Internet transit provider loans them. That allows them
to change transit providers without disrupting their internal network.

In IPv4, RFC1918 gives them that address stability, but then thrusts
upon them the issues that NAT and duplicate/overlapping
addressing creates.

So the goal is:

- stable addressing, independent of the stability of your transit
  provider's addresses that they temporarily loan to you
- globally unique, or unique enough that collisions are very unlikely
  to occur, should you wish to permanently or temporarily interconnect
  domains (e.g. VPN)
- user generated, so there is no cost or need to interact with a
  central authority

and as IPv6 has formalised the support of interfaces having multiple
addresses, ULAs suit those requirements.

> -chris
> >
> >> -Chris
> >>
> >

More information about the NANOG mailing list