In message <4c6c6fc3-d1a9-4663-a1e1-802d1a6d0...@apple.com> james woodyatt writes: > On Oct 12, 2011, at 1:52 PM, Curtis Villamizar wrote: > > > > A router should not start handing out PD or even IPv4 NAT space > > until it gets and address from elsewhere.
btw - the valid point about serving the site needs was brought up, so some assignment would be needed in absense of an uplink. > Some routers need to do this, i.e. home routers where service > providers charge prohibitive rates for always-on Internet dial-tone > and expect subscribers to connect on demand and disconnect after an > appropriate idle time. For on-demand routing, it makes sense for the router to hand out an address while not being connected. I personally haven't seen that since 56K modems, but OK. (And I had FR back then). For the DSL and MSO services I've used, the service was "always up", unless of course you powered down the CPE. > For IPv4 today, these routers typically use PPPoE on the WAN and they > often handle this by assigning RFC 1918 address to the LAN hosts and > using DNS queries to signal PPPoE to establish the WAN link. OK. Client does DNS and that is the "on demand" part. Fine. In in absence of DNS, a ping or TCP SYN would bring it up. > For IPv6, I'm not sure what they should do, but I have some ideas. > Basically, the router should advertise as a default router with a > single ULA prefix and a DNS server at the router's ULA interface > address with RFC 6106 and optionally RFC 3736. When the DNS query > signals PPPoE to establish the WAN link, the DHCPv6 client will ask > for a IA_PD and update the prefix advertised on the LAN accordingly. > > I'm not sure this model can be made to work with IPv6, but I wouldn't > put it past the telcos to try. With IPv6 there is no reason that the CPE can't be assigned a persistant address but bring the connection down. On power up it could connect and get it, then bring the link down in the absence of traffic. Usually if it is powered up it is because someone want to use it, so this would be fine. There is no reason not to hold the IA_PD assignment at the CPE when an on demand link is down. That prefix can be requested in the IA_PD request when there is demand again, just to refresh it and confirm. The same DNS query can be used as the trigger in on-demand IPv6 as well. Curtis _______________________________________________ homenet mailing list homenet@ietf.org https://www.ietf.org/mailman/listinfo/homenet
