On Mon, 29 Mar 2010 17:34:30 -0500 "Frank Bulk - iName.com" <[email protected]> wrote:
> Did you get assigned a /48 that you feel that you are address constrained? > No. > The whole point of IPv6 is plentiful addresses. At this time I'm planning > to assign a /64 per PPPoE link, and if they want it, a /56 via DHCP-PD. > I'm happy with using /64s for PPPoE links. However, if the /127 draft is accepted, then I'd want to be able to take advantage of them on PPP/PPPoE sessions - if there is an approved mechanism available to save address space I may as well use it. While RAs do support prefix lengths in their PI option, there isn't a mechanism specified on how to do autoconf in a /127 (or rather, who gets the 0 or 1 address). As DHCPv6 is going to be run over that link anyway to acquire DNS addresses etc., it might be better to build the /127s autoconf mechanism into that. This new DHCPv6 option could also imply a default route/router, which the eliminates the requirement for the upstream BRAS to generate periodic, per-PPPoE session/prefix specific RA announcements. That could be a useful thing to eliminate, as generating pre-PPPoE session specific RAs (due to different prefixes), could start to be a significant control plane load when there are multiple 10s of 000s of PPPoE subscribers attached to the same device. Regards, Mark. > Frank > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Mark > Smith > Sent: Monday, March 29, 2010 4:47 PM > To: Mark Smith > Cc: Becca Nitzan; [email protected]; [email protected]; George, Wes E [NTK]; > [email protected]; Miyakawa; [email protected] > Subject: DHCPv6 support for /127s, for ISP subscriber PPP/PPPoE p2p links > (Re: router vs. host discussion in 6man today for the /127 draft) > > Hi, > > The subject pretty much says it. It's extremely wasteful to be > allocating a /64 per subscriber PPP/PPPoE session. > > An alternative model is lay a "virtual" /64 over the top of the 100s or > 1000s of PPP/PPPoE sessions, and have the subscriber's PPP IID used to > autoconf the LL and global addresses. However that's vulnerable to the > /64 issues, and because IPv6 over PPP defaults to allowing disabling > DAD, could also suffer from duplicate addresses. There is a caveat to > allow DAD to be re-enabled, but with cheap residential CPE, that > couldn't be relied on. > > Also it'd be worth making DHCPv6 support announcing a default > router/route to these end nodes, so that the upstream BRAS doesn't have > to issue periodic RAs. In either the /64 per P2P link or the single > "shared" model, with 100s (or more typically 1000s) of subscribers > attached, the router will have to spend a reasonable amount of > resources on sending RAs down the individual PPP/PPPoE sessions. > > Regards, > Mark. > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > [email protected] > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- > -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
