The Choice: IPv4 Exhaustion or Transition to IPv6

Jamie Bowden jamie at
Fri Jun 29 14:37:43 UTC 2007

-----Original Message-----
From: owner-nanog at [mailto:owner-nanog at] On Behalf Of
Kevin Oberman
Sent: Thursday, June 28, 2007 1:15 PM
To: Stephen Wilcox
Cc: John Curran; nanog at
Subject: Re: The Choice: IPv4 Exhaustion or Transition to IPv6 

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


Sorry for the horrid formatting, but LookOut is corp. standard.

As for your claim that these are wasted, I take issue with this.  I have
connectivity to several different classified networks, and all of them
are segregated, but they DO have gateways so that specific things can
pass between them.  There isn't enough 1918 space to reconcile the
number to .gov and contractor sites on these networks without hitting
collisions, and they can't be aggregated despite overlap (like I said at
the beginning, we have several coming in...) because they aren't all at
the same classification level (which is why they have strictly
controlled gateways between them).

Jamie Bowden
"It was half way to Rivendell when the drugs began to take hold"
Hunter S Tolkien "Fear and Loathing in Barad Dur"
Iain Bowen <alaric at>

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