In message <e82ea149-2530-41ff-9ce0-670e6cd7d...@delong.com>, Owen DeLong writes: > > > On Nov 25, 2015, at 15:59 , Mark Andrews <ma...@isc.org> wrote: > > > > > > In message > <CAMWxDfrh+O=SPZwPmAZhYnvAEeK2eMFw3CD0qf34Fkbb=-s...@mail.gmail.com>, > Brian Knight writes: > >> On Tue, Nov 24, 2015 at 6:34 PM, Baldur Norddahl > >> <baldur.nordd...@gmail.com> wrote: > >>> > >>> DHCPv6-PD allows multiple PD requests. But did anyone actually > implement > >>> that? I am not aware of any device that will hand out sub delegations > on > >>> one interface, notice that it is out of address space and then go > request > >>> more space from the upstream router (*). > >>> > >>> DHCPv6-PD allows size hints, but it is often ignored. Also there is no > >>> guidance for what prefix sizes you should ask for. Many CPEs will ask for > >>> /48. If you got a /48 you will give out that /48 and then not honor any > >>> further requests, because only one /48 per site is allowed. If you are an > >>> ISP that gives out /48 and your customers CPE asks for a /56 you will > >>> still ignore his size hint and give him /48. > >> > >> Or, worse, the ISP's DHCPv6 server honors the new request and issues > >> the larger prefix, but refuses to route it. Ran into that myself when > >> I replaced my home CPE router, and changed the prefix hint to ask for > >> a /60 block (expanded from /64) at the same time. That made for a > >> frustrating few days without IPv6 service, waiting for my original > >> delegation to expire. (Tech support, of course, had no clue and > >> blamed my router.) > >> > >> In retrospect I should have perhaps had my original CPE generate a > >> DHCP release message for that prefix before disconnecting it. But I > >> won't be the last person to fail to generate that. > >> > >> -Brian > > > > Well the requesting router could announce the route. ISC's client > > has hooks that allow this to be done. That is, after all, how > > routing is designed to work. The DHCP server usually is sitting > > in a data center on the other side of the country with zero ability > > to inject approptiate routes. > > Are you really suggesting that a residential ISP accept routes advertised > from their customerâs CPE? Really?
PD is used internally as well as externally, and with a little bit of crypto to prove the assigned address belongs to them there really isn't a reason a CPE device couldn't announce a address to a ISP. It would also allow BCP38 filters to be built rather than using RFP which is only a approximate solution. > Thatâs about the most ridiculous thing Iâve heard on NANOG in a long time > and thatâs saying something. > > > The DHCP relay could also have injected routes but that is a second > > class solution. > > Maybe, but in an ISP/Customer PD environment, itâs certainly preferable > to what you consider a âfirst classâ solution. Actually it is still a second class solution. Have the CPE generate the routes and use information from the relay as a acceptance filter. That way the device that was delegated the prefix decides what it announced. > Owen -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
