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

[Owen DeLong <owen () delong com>]

On Oct 20, 2010, at 9:30 PM, Graham Beneke wrote:

> On 21/10/2010 02:41, Owen DeLong wrote:
> > On Oct 20, 2010, at 5:21 PM, Jeroen van Aart wrote:
> > > Someone advised me to use GUA instead of ULA. But since for my purposes this is used for an IPv6 LAN would ULA not 
> > > be the better choice?
> > IMHO, no. There's no disadvantage to using GUA and I personally don't think ULA really serves a purpose. If you want 
> > to later connect this
> > LAN to the internet or something that connects to something that connects to something that connects to the internet 
> > or whatever, GUA provides
> > the following advantages:
> >      +       Guaranteed uniqueness (not just statistically probable uniqueness)
> >      +       You can route it if you later desire to
> >
> > Since ULA offers no real advantages, I don't really see the point.
>
> Someone insisted to me yesterday the RFC1918-like address space was the only way to provide a 'friendly' place for 
> people to start their journey in playing with IPv6. I think that the idea of real routable IPs on a lab network 
> daunts many people.
They should get less daunted. You can always put a firewall with a deny all policy or an air-gap in front of it if you 
don't want to talk to the internet.

> I've been down the road with ULA a few years back and I have to agree with Owen - rather just do it on GUA.
Thanks.

> I was adding IPv6 to a fairly large experimental network and started using ULA. The local NREN then invited me to 
> peer with them but I couldn't announce my ULA to them. They are running a 'public Internet' network and have a 
> backbone that will just filter them.
Uh huh. Now, imagine if, instead of a small experimental deployment, you had a fortune 500 enterprise and instead of an 
NREN it was an ISP for whom you were a major customer... Any bets on which side of that equation gets the policy change?

> I think that the biggest thing that trips people up is that they think that they'll just fix-it-with-NAT to get onto 
> the GUA Internet. Getting your own GUA from an RIR isn't tough - rather just do it.
I completely agree.

Owen