We're requesting a /10, not a /12 or /15 (devices attached to one CGN
might use the whole /15). Such an allocation would be too small for a
regional CGN deployment at a larger ISP, and would likely result in
double-CGN. Shared CGN Space really needs to be a /10.
Second, many ISPs do not control customer home network addressing
decisions. It is not feasible to tell a customer to renumber, especially
when the customer is legitimately using RFC1918 space in accordance with
Unfortunately, your proposal doesn't actually solve the problem we're
On 12/7/11 3:35 PM, "Måns Nilsson" <mansaxel(_at_)besserwisser(_dot_)org> wrote:
Subject: Re: Consensus Call (Update):
draft-weil-shared-transition-space-request Date: Wed, Dec 07, 2011 at
11:31:11AM -0800 Quoting David Conrad (drc(_at_)virtualized(_dot_)org):
On Dec 7, 2011, at 10:39 AM, Michael Richardson wrote:
The CGN space seems like a very good place to use 240.0/10.
I believe the main driver behind this discussion is the need to deal
with deployed non-field-upgradable CPE that has issues with having RFC
1918 space being assigned on the WAN interface. I'd guess said hardware
would also likely have issues with 240/4 space being instead.
I believe we can narrow the problem with RFC 1918 addresses down to "same
or overlapping prefix on the outside as inside", rather than assuming
that any use of 1918 space on the outside interface is detrimental.
Does anybody know of any evidence to the contrary?
Vendor default allocations of RFC1918 to "broadband router" LAN interfaces
are limited to nets 10 and 192.168. Does anybody know of any evidence to
Therefore, point out a /15 from 172.16.0.0/12 and be done with it. The
few conflicts arising will fall in two classes:
a/ People who have knowingly changed their LAN prefix.
b/ Organisations large enough to use _all_ of RFC 1918 inside.
"a" means they can change again. Problem solved.
"b" means that they are large enough to be able to buy public external
addresses, if they do not already posess swamp space. Problem solved.
Måns Nilsson primary/secondary/besserwisser/machina
MN-1334-RIPE +46 705 989668
Now I understand the meaning of "THE MOD SQUAD"!
Ietf mailing list