[AusNOG] IPv4

Mark Newton newton at atdot.dotat.org
Mon Mar 4 12:35:52 EST 2013

On 04/03/2013, at 10:00 AM, Bob Purdon <bobp at purdon.id.au> wrote:

> I reckon one area the relevant NIC's should explore is the reclaiming of unused legacy space.  
> Some will argue that this was "given" to these organisations many years ago, but things can and do change.

There are two things to keep in mind while having this discussion:

Global demand for IPv4 is about one /8 per month.

And we've already had this conversation approximately every month for the last few years :)

> I'm thinking of the universities that are sitting on /16's, yet announcing only a /24 or two from that range.  I believe the US military, and various large corporations are also guilty of sitting on /8's.

Okay, let's assume you can convince the US military to give up a /8.

(you can't, but let's play the game anyway)

If they went through all the effort of renumbering their internal networks
away from it, they'd give the world one month of growth. 

So we could put this thread on hold, and restart all the recriminations and
chest-beating after Easter.

Alternatively, let's assume we can go to a university and convince them to
renumber away from a /16 (beside the fact that universities tend to be very
large enterprises who actually _need_ large swarthes of IPv4 space, but again,
let's play the game anyway).

If we were successful, and they renumbered into something else, and gave
back their /16, that'd give the world approximately 2 hours of growth.

Now:  Will it take more than two hours to accomplish the renumbering, go through
the legals, update the IANA documentation, etc?  Pretty sure it will.

Of course, we're looking at this in an environment where this allegedly 
unused address space is actually quite valuable, and where the same university
could simply sell it on the open market for about $14 per address if they 
weren't using it. That's almost a million bucks for a /16;  If they were genuinely
"wasting" it, don't you think they'd have sold it already?

> The NIC's should be looking at what is announced and for space that's
> not the owners should be required to announce it (with useful/meaningful
> services occupying it), or hand it back.

There's never been a requirement to announce space.  Quite a lot of it is
used for purposes where uniqueness is required, rather than purposes where
global reachability is required.

I know at least two organizations with legacy /8's who use enormous quantities
of it for extranets and intranets which are separate from the internet, but 
which must be uniquely numbered because the third party enterprises they're
connecting to aren't separate from the internet.  They can't use RFC1918, so
their alternatives are to either use registered address space, or to poach
someone else's registered address space.  Which alternative is better?

> If it's not in the global routing table then you don't need it (you should renumber into RFC1918 space and NAT, since if you are using the space you're obviously NATing it).

Have you ever tried to merge two companies that both make extensive use of
net-10?  It's a nightmare.  Far better if at least one of them is using registered
address space. (IPv6 will make these kinds of network mergers much, much easier,
for obvious reasons)

> If you are announcing it, but nothing is listening (even residential DSL users are often pingable and a small percentage have something
> listening)

Windows doesn't respond to ping when firewalling is enabled.  Not a good test.

> I'm sure none of that is perfect, but perhaps it could form the basis for some form of space reclamation policy?

Is there any point?  

Let's say you manage to scrounge together half a dozen /8's.  Great, we can 
start feeling upset about IPv4 again during the second half of this year.

And this is all in a world where the RIR's don't actually claim any authority
at all over legacy IP address space, because the recipients were never required
to agree to their terms and conditions.  If APNIC goes to a Government department
and says, "Give us back your /16," and the Government department tells them to
go away, what happens next?

  - mark

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