Mark; Good points all. Yes, in many cases I agree - that large an enterprise would have multiple ISPs, and may choose multiple unrelated /48s for their global offices, and then could use multiple /48 ULAs to tie it together. And map subnets - if they wanted - such that a single subnet had, for example, 2001:DB8:4:6::/64 and FD92:A054:B18E:6::/64.
But if, for whatever reason, the enterprise chose a single /46 from a single (global) ISP, and wanted to use it all over the world, they might want a /46 ULA to go with it, I think. John Spence > -----Original Message----- > From: Mark Smith > [mailto:[EMAIL PROTECTED] > Sent: Friday, September 23, 2005 2:26 AM > To: John Spence > Cc: ipv6@ietf.org > Subject: Re: Can I generate a prefix shorter than /48 using > <draft-ietf-ipv6-unique-local-addr-09.txt>? > > Hi John, > > On Thu, 22 Sep 2005 19:55:27 -0700 > "John Spence" <[EMAIL PROTECTED]> wrote: > > > > > If my organization is large, and I will petition my ISP for > a /44, or > > even a /40, I'd like to be able to use the mechanism > outlined above to > > randomly generate myself a Unique Local /40 prefix so I can map my > > routable and site-restricted space as I desire. > > > > Out of interest sake, if you are able to tell me, I'm curious > how large ? I'd have thought a /46 or 256K subnets would have > been large enough for the largest organisations in the world, > even allowing for unused subnets due to aggregation to allow > for multiple instances of IGPs separated by BGP internally, > as IGPs may be limited in how many subnets they can carry. At > least to me, a /40 (or just a /40 size address space of > different /48s) for a single organisations' subnet > requirements is pretty much inconceivable. > > > I did not see a provision in the draft that would allow me > to do that. > > Is that correct - there is no provision for generating a shorter > > prefix? > > > > I agree with Pekka, you're probably going to have to divide > up your routing protocols into IGP instances / private ASes > just to cope with that many subnets anyway, I'd think inside > your organisation different ULA /48s corresponding to these > IGP instances / private ASes would be resonable. > > I'd also think having a separate public Internet connection > for each of those /48s or 65 K subnets is at least likely > (for no other reason that having your phone ring when more > than that many users lose their Internet access would cause > it to melt!), and therefore using global /48s along those > same boundaries would also make sense, and allow you to use > the same subnet numbers for the ULA and global /48 within > each IGP instance / private AS division. > > Regards, > Mark. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
