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

[Owen DeLong <owen () delong com>]

On Oct 20, 2010, at 5:21 PM, Jeroen van Aart wrote:

> Deepak Jain wrote:
> > According to the RFC: 
>
> > 3.2.1.  Locally Assigned Global IDs
> >   Locally assigned Global IDs MUST be generated with a pseudo-random
> >   algorithm consistent with [RANDOM].  Section 3.2.2 describes a
>
> > Global ID in this case means the 40 bit pseudo random thing. The point here is, we are all supposed  to pick our own 
> > poison and pray that we are unique. Though an algorithm is suggested in 3.2.2. Perhaps SIXXS uses it. Anyway, the 
> > SIXXS tool seems pretty slick.
>
> All thanks for the information. I'll be using the "40 bit pseudo random thing" since it seems to be the smart thing 
> to do, using the SIXXS tool. One may hope that something will become the "official" way to generate these numbers 
> (perhaps the above mentioned tool).
I believe the above mentioned tool uses the OFFICIAL way documented in the RFC.

There is an official way to do it. It is documented in the RFC.

> 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.

Owen