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

[Deepak Jain <deepak () ai net>]

> Use a pseudo random number, not follow bad examples. Where are these
> examples? I'd be curious as to what they say regarding why they haven't
> followed the pseudo random number requirement.
>
> > Use something like fd00::1234, or incorporate
> > something like the interface's MAC address into the address? It'd
> make
> > the address quite unreadable though.
> Unique Local IPv6 Unicast Addresses
> http://tools.ietf.org/rfc/rfc4193.txt

[snipped a bunch of stuff above]. 

According to the RFC: 

3.2

   The local assignments are self-generated and do not need any central
   coordination or assignment, but have an extremely high probability of
   being unique.

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
   suggested algorithm.  It is important that all sites generating
   Global IDs use a functionally similar algorithm to ensure there is a
   high probability of uniqueness.

   The use of a pseudo-random algorithm to generate Global IDs in the
   locally assigned prefix gives an assurance that any network numbered
   using such a prefix is highly unlikely to have that address space
   clash with any other network that has another locally assigned prefix
   allocated to it.  This is a particularly useful property when
   considering a number of scenarios including networks that merge,
   overlapping VPN address space, or hosts mobile between such networks.

----

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.

Deepak