james woodyatt wrote:
[..]

> I merely contend-- albeit heretically-- that "L=0" in RFC 4193 is
> nonsense. We should hand fc00::/8 back to IANA and revise RFC 4193 so
> that fd00::/8 is the ULA prefix identifier, where all addresses are
> allocated according to to the procedure currently defined, have global
> scope, are not routed in the DFZ and receive synthetic reverse
> delegations in 0.0.d.f.ip6.arpa to an anycast address reserved by IANA.

The Local/Global bit is correct in the specification and also what
differentiates the two spaces, the L bit set (thus fd00::/8 RFC4193)
means that the prefix is locally generated and not 100% guaranteed
unique, although 2^-40 is pretty close to that. This is exactly what we
have now. Without the L bit (thus fc00::/8 and proposed ULA-C) we
require some kind of registry to intervene and keep a list to make sure
that there is no collision.

I agree on the handing back of fd00::/8. The need for an address space
like ULA-C is covered by PI already(*1). There are a few corner cases
like "very small sites" but these can be resolved with proper RIR
policies. It is IMHO very wrong that there are folks who want to
restrict RIR's providing address space to end-sites due to 'routing
table' issues which are not existent yet and of which various vendors
have mentioned already that it is and will not be a problem.


What you thus propose above is adding the synthetic 0.0.d.f.ip6.arpa
method as an addition to RFC4193.

Although I partially like the idea it only solves the reverse problem.
It does not solve the forward problem. Because of the latter one still
has to configure DNS on both (or all of the other) connecting sites
anyway to link up these address spaces for the forward zones. One can
then also easily add this for reverses.

This then also doesn't deviate from current practice in both IPv4 and
IPv6. It also doesn't squander a part (/64?) of the /48. Randomly
picking an address in that /48 makes the whole /48 useless as people
can't depend on the full /48 being theirs anymore to slash up(*2).
Also a lot of deployed IPv6 sites use the first /48 for their first
network already or for similar purposes. Next to that there will be at
some point an expectancy that the same synthetic mechanism exists for
the rest of the ip6.arpa zone.


*1 = If one really wanted to one could simply become LIR, request a /32,
then started providing /48's to their customers, who would be people who
simply wanted a chunk of address space. This solves *ALL* this hassle
about ULA-C. The LIR could be setup as a join venture owned by the users
of the address space, thus as long as at least one of them has some cash
they can keep the LIR running and keep the address space.


*2 = as a side note, for SixXS we provide in general two sizes of
prefixes: /64 which is used for tunnels and /48 which is used for
subnets. The /48 is routed fully to the user, as such they can do
anything they want with it, chunk it up in any way possible. If they
then ever move to another ISP they can use the exact name numberplan.
The only 'renumbering pain' left is locating where they have all the
first 48 bits stored and changing those.

Greets,
 Jeroen

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