On 12/1/11 4:27 PM, Ted Hardie wrote:
On Wed, Nov 30, 2011 at 6:14 PM, Pete
Resnick <presnick@xxxxxxxxxxxx>
wrote:
The problem described in the
draft is that CPEs use 1918 space *and
that many of them can't deal with the fact that there might be
addresses on the outside interface that are the same as on the inside
interface*. The claim was made by [Robert], among others, that only
192.168/16 space was used by such unintelligent CPEs. I believe I have
seen the claim that 10/8 space is also used in unintelligent equipment
that can't deal with identical addresses inside and outside. Is there
reason to believe that within the ISP network / back-office etc. that
there is equipment that can't deal with 17.16/12 space being on both
the inside and outside? I haven't seen anyone make that specific claim.
If we know that 172.16/12 used both inside and outside will break a
significant amount of sites that CGNs will be used with, we can ignore
this argument. But if not, then let's rewrite the document to say that
CGNs should use 172.16/12 and that any device that wants to use
172.16/12 needs the ability to deal with identical addresses on the
inside and the outside interface. Of course, all equipment should have
always been able to deal with identical addresses inside and outside
for all 1918 addresses anyway. But if we think the impact of using
172.16/12 for this purpose will cause minimal harm, then there's no
compelling reason to allocate new space for this purpose.
I wrote a response to Brian's original statement then deleted it
because I assumed others would ignore it as clearly last minute and
ill-researched. Apparently, that was wrong. There are enterprises
that currently use 172.16/12. (There are enterprises which use every
tiny piece of RFC 1918 space.)
Ted, your response does not address what I said at all. Not one bit.
Let's assume that *every* enterprise used every last address of
172.16/12 (and, for that matter ever bit of 1918 space). That's
irrelevant and still does not address my question. The question is
whether these addresses are used BY EQUIPMENT THAT CAN'T NAT TO
IDENTICAL ADDRESSES ON THE EXTERIOR INTERFACE. I am happy to accept an
answer of, "Yes, all 1918 address space is used by such equipment", but
nobody, including you, has actually said that.
*Any* piece of the current RFC 1918 space you attempt to define
as being used for this will conflict *somewhere*. Anyone who happened
to chose this for an enterprise deployment and gets
stuck behind a CGN would be forced to renumber, in other words, because
of this statement.
That statement does not logically follow from "all 1918 address space
is used". You are missing a premise: "There exists equipment that is
used in all of that space that can't handle identical addresses on the
interior and exterior interface."
The current draft says that the reason 1918 space can't be used is that
equipment that deals in 1918 address space is hosed if 1918 addresses
are used on their external interface. Brian claimed that perhaps
172.16/12 space might not be used by that equipment. Robert claimed
that perhaps only 192.168 and 10.0.0.x addresses are used by that
equipment. So the question I posed was, "Does any of *that* equipment
use 172.16/12 (or 10.x/16) space?" Nobody has said "yes".
And *I'm* still not claiming that the answer is "No." I simply don't
know. But I'm inclined to hear from anybody to indicate that there is
*any* evidence that the answer is "Yes". That would make me much more
comfortable in concluding that new specialized address space is the
better horn of this bull to throw ourselves on.
pr
--
Pete Resnick <http://www.qualcomm.com/~presnick/>
Qualcomm Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102
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