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 the RFC. Unfortunately, your proposal doesn't actually solve the problem we're facing. Chris On 12/7/11 3:35 PM, "Måns Nilsson" <mansaxel@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx): >> Michael, >> >> 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 >the contrary? > >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 Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf