The Choice: IPv4 Exhaustion or Transition to IPv6

Mailman List Mirror (Read Only)
1

Date: Thu, 28 Jun 2007 17:42:47 +0100
From: Stephen Wilcox <steve.wilcox@packetrade.com>
Sender: owner-nanog@merit.edu

Hi John,
I wasnt specifically thinking of reclamation of space, I was noting a
couple of things:

- that less than 50% of the v4 space is currently routed. scarcity will presumably cause these non-routed blocks to be:
:- used and routes
:- reclaimed and reassigned
:- sold on

Some of it, but a large part of the "missing" space belongs to the US
Government, mostly the military. It is very much in use and is routed
carefully such that it does not show up in the public Internet. It might
be replaced with RFC1918 space, but I'm not sure that there is enough
1918 space to do the job as the address space needed is quite large.

Also, some is used where 1918 space certainly could be used, but I have
spoken with those responsible to ask them to move to 1918 space and the
answer is an unequivocal "NO", not now or ever. I don't understand this,
but I know it exists. One research lab has multiple /16s and several are
used by classified nets that lack any external connectivity.

While these are wasted, getting them back is essentially impossible.

- that much of the space in use within organisations could be optimised
:- mop up unused gaps in subnet
:- return IPs to the org's pool by forcing departments onto NATs

Pushing to NAT is on the face of it similar to pushing for early
adoption of v6 whereby v6-v4 gateways provide a translation. However
the technology for NATs is well established, widely deployed, cheap
and very understandable to any IT guy.

You also refer to routing table size. The current routing table is
growing quickly but people have been predicting the tables will
outgrow the technology for many years but in each case new hardware
gets released and on modern routers we can take significant growth
(400%?).

Not really. See the presentations by the major router vendors on FIB
size from NANOG39 in Toronto at <http://www.nanog.org/mtg-0702/jaeggli.html&gt;\.

Most large network operators are truly frightened at the prospect of
what we are facing. There are some very real issues beyond adding more
TCAM. Issues that IPv6 will probably make worse. Right now the
available TCAM is mostly allocated to IPv4 unicast and very little to
IPv6. If the IPv6 table gets very large (and each IPv6 entry takes up
four times the space in TCAM as an IPv4 entry), the choice is rather
painful.

I dont believe routing table size comes into play in this, the simple
reason is that whatever we say there will always be companies willing
to take routes for money and it doesnt matter who or where they are
because the rest of the world just has to route it.

I dont think that hierarchical routing will ever be a reality in
todays diverse internet backbone, to not be a top tier carrier with
your own ASN, and a full set of routes means you are closing your
doors on selling transit. There are many thousand organisations making
money from that, I cant see 99% of them bowing out gracefully to leave
a few 'tier1s' behind.. that would be like turning back the clock 15
years.

In the current routing schemes there is a large issue here.
Hierarchical routing simply won't do the job in a global fashion, but
there is work going on on new techniques that could deal with this.
Vince Fuller, Dave Meyer, Dave Oran, and Dino Farinacci presented an
approach at the last NANOG:
<http://www.nanog.org/mtg-0706/Presentations/lightning-farinacci.pdf&gt;
They are not the only ones working on resolving this issue.

2

Kevin Oberman wrote:

<SNIP>

While these are wasted, getting them back is essentially impossible.

The term wasted is being used way to freely on this list.

If by waste you mean:

To use, consume, spend, or expend thoughtlessly or carelessly.

Then I have to disagree.

If you mean they (unannounced addresses) are being underutilized. Then
say so.

Note that even the current ARIN NRPM can be used a basis for assigning
addresses based on need that are not intended to be announced (4.3.5)
it does assume that they will be routed but not where they will be
routed to.

3

Kevin Oberman wrote:

From: Stephen Wilcox <steve.wilcox@packetrade.com>
   
I wasnt specifically thinking of reclamation of space, I was noting a
couple of things:

- that less than 50% of the v4 space is currently routed. scarcity will presumably cause these non-routed blocks to be:
:- used and routes
:- reclaimed and reassigned
:- sold on
   

Some of it, but a large part of the "missing" space belongs to the US
Government, mostly the military. It is very much in use and is routed
carefully such that it does not show up in the public Internet.

There's another set of missing space, here. It seems to be the elephant in the room. While I can't (or won't) speak to the routing issues mentioned in the thread, I wonder that no one has brought up all the legacy space that is held by a few large conglomerates. No, I'm not talking about AT&T, here. I refer to the early days, when class B networks were handed out like penny candy, and when organizations could get class C space equivalent to a class B. When Company A has, say, 5 or 6 of those, and then acquires Company B, and then C and D, and all of them have that same allotment, it becomes a non-trivial amount of space. If there's really only 5 or 6 big companies, where there used to be 50 or so, we are suddenly talking about a non-trivial amount of space.

Unfortunately, there's no good way to make them give it up. When you can see that they could easily make do with a single /8 (or less), it's rather sad that we don't have a mechanism in place that punishes for greed, and rewards for surrender of unused (or at least completely unnecessary) space. I only know about the industry I came from, of course, and I suspect that the lion's share of over-allocation is in it. I rather doubt that such things as banking, which came late to the table, have that characteristic. I know it's not a permanent answer, but it seems that (unlike the black space over on milnet et al) there's a temporary reprieve to exhaustion in there somewhere.

4

Date: Thu, 28 Jun 2007 17:42:47 +0100
From: Stephen Wilcox <steve.wilcox@packetrade.com>
Sender: owner-nanog@merit.edu

Hi John,
I wasnt specifically thinking of reclamation of space, I was noting a
couple of things:

- that less than 50% of the v4 space is currently routed. scarcity

will presumably cause these non-routed blocks to be:

:- used and routes
:- reclaimed and reassigned
:- sold on

Some of it, but a large part of the "missing" space belongs to the US
Government, mostly the military. It is very much in use and is routed
carefully such that it does not show up in the public Internet. It might
be replaced with RFC1918 space, but I'm not sure that there is enough
1918 space to do the job as the address space needed is quite large.

Also, some is used where 1918 space certainly could be used, but I have
spoken with those responsible to ask them to move to 1918 space and the
answer is an unequivocal "NO", not now or ever. I don't understand this,
but I know it exists. One research lab has multiple /16s and several are
used by classified nets that lack any external connectivity.

While these are wasted, getting them back is essentially impossible.