[arin-ppml] Use of "reserved" address space.

Leo Bicknell bicknell at ufp.org
Sun Jun 27 19:23:33 EDT 2010

In a message written on Sun, Jun 27, 2010 at 11:09:24AM -0700, Owen DeLong wrote:
> But pulling resources off of IPv6 deployment to make this address space
> workable, even in the scenarios you suggest simply doesn't make sense.
> Taking resources away from a solution in order to propel a hack that will
> by all accounts take nearly as long as the solution in order to develop
> and deploy, especially when the solution already has momentum and
> is accelerating simply doesn't make sense to me.

The two are not mutually exclusive.  For instance, some providers
have decided to deploy IPv6 over MPLS because their core devices
can't support IPv6 forwarding in hardware.

However, you can't bring up MPLS without IPv4 addressing, as right
now the various MPLS protocols are tied to IPv4 IGP's in interesting

So imagine a new entrant down the road.  We've thought about these
folks, wanting to set aside space for them to be able to enter the
market; see a good part of the discussion on "the last /8".  Imagine
if they could turn up a core in 240/4, which would be relatively
easy for them to insure all of their boxes supported, and then run
IPv4 and IPv6 over MPLS.

Even if their core was used natively for IPv4, devices "far away"
that filtered it would have the same issues that today cores using
10/8 have; PMTU might break if the lower MTU is on a "filtered"
block, your traceroute may look funny, but the packets get from A
to B.

In fact not all end points need to be upgraded to make 240/4 work.
It could be used inside of ISP's to conserve other globally routeable
space, or to allow a new entrant to bring up an IPv6 core, all by
only having a single ISP make sure they are upgraded.

This is one of those areas where I frankly don't understand the
reluctance of most of my colleagues in this area.  Change it from
reserved to SHOULD be treated as Unicast (note, not must).  Set a
simple policy that the IANA can hand it out post run-out to the
RIR's.  The RIR's can hand it out with gigantic 72 point font
multi-page disclaimers that it may not work on the global Internet.
Cost to the standards and policy process, virtually zero.

If a vendor makes it work on their hardware, and an ISP finds a way
to use it, great, we helped someone make the Internet go.  If no
one uses it, oh well, at least people can't say we didn't try
everything possible.

Seriously, do you really think this will draw critical resources away
from IPv6?

       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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