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Re: My thoughts on local-use addresses

2003-04-29 07:21:21


--On Saturday, 26 April, 2003 13:02 -0400 Keith Moore <moore(_at_)cs(_dot_)utk(_dot_)edu> wrote:

we need to get rid of site-locals.  merely renaming them as
private use addresses wouldn't solve any of their problems.
there's no advantage to moving to IPv6 if it repeats the RFC
1918 mistake.

Keith,

Given the tone of some of the traffic on these subjects in the last few weeks, this probably needs to be said in public, and I apologize for singling you out because you are certainly not the only offender.

Hyperbole does not serve either the community, or one's own position, well in this situation or others like it. Suppose we start making a list of problems that IPv6 doesn't solve --routing, security, cancer, even NATs -- or just carries forward from IPv4. If we then take that list and use it to construct statements of the form of "there's no advantage to moving to IPv6 if it doesn't solve X or repeats Y", we would really be asking the community to forget the problems IPv6 does solve (or at least helps with).

If we were using that approach and logic in the mid-70s, we would probably be trying to run the network on NCP --and an address space of 254 or so hosts-- today, presumably with either the demon grandchildren of NATs or some offspring of a NAT and an X.75 gateway.

Specifically...

        * Like you, I'd like to get rid of NATs.   I agree that
        private address spaces tend to encourage NATs, although
        not as much as running out of address space does.   If
        IPv6 is able to reduce the number of NATs by even
        25%-50%, that would, IMO, create a significant advantage
        for moving to IPv6.  Getting rid of all of them would be
        better, of course, but claiming or implying "no
        advantage" if all of them can't be removed is really a
        bit much, don't you think?
        
        * Like it or not, there seems to be a strongly-perceived
        requirement for non-RIR-dependent (neither PI nor PD-but-
        RIR-allocated) addresses.  That requirement is arguably
        legitimate for completely detached networks, even if one
        believes in globally-unique addresses for every network
        or host that is even vaguely connected.  Many years ago,
        I could come to the NIC and say "I need some
        (globally-unique) addresses for a LAN that will never
        be connected to the Internet" and get them.  Today,
        the RIRs have no procedures for dealing with such a
        request, much less making the allocation, in either IPv4
        or IPv6 space.  I would hope that, were someone to
        make it, he or she would get an explanation, rather than
        polite laughter, but the requirement is there.   And it
        seems to me that we either need to figure out how people
        can get addresses for that narrow purpose or reserve
        some "open-season" addresses for them.  That is clearly
        independent of whether it is rational to have SL
        addresses on hosts that might be connected to the public
        network --either through NATs or multiple addresses--
        but it means that having some such addresses around
        doesn't turn IPv6 into "no advantage".
        
        * There has been increasing evidence, as this set of
        discussions have played out, that SL isn't the problem,
        but merely a symptom of a series of issues with scopes
        and/or routing and/or layering and data abstraction.  If
        we figure out how to solve the appropriate set of those
        issues, SL will either go away or not, but it is
        unlikely to be a big issue.  Absent a huge intellectual
        breakthrough (and a model for deploying it easily),
        these look likely to work out as complex tradeoffs in
        which we need to make decisions about optimality, or
        damage-minimization, rather than coming up with a
        perfect solution that meets all needs and creates
        universal pleasure.  Are you going to pick some point in
        that solution space, or the subspace that doesn't happen
        to contain SL, and say "if we don't get to this point,
        IPv6 is worthless"?  I don't think so or, at least, I
        hope not.

So, if possible, let's try to calm it down a bit, stop the hyperbole, and get back to thinking and reasoning carefully about a complex problem. Please.

       john