On 22/02/13 14:50, Ted Lemon wrote: > On Feb 22, 2013, at 8:24 AM, Simon Kelley <si...@thekelleys.org.uk> wrote: >> It works as well for clients which do DHCPv4 and SLAAC. IPv6-only hosts >> would have to do stateful DHCPv6, but the DHCPv4 and SLAAC model covers >> an awful lot of currently-deployed clients. > > So dnsmasq is noticing that the IPv4 and IPv6 hosts are the same host using > the MAC address or something, and then coordinating the DNS registration? > > As the DHCPv4 state machine moves to "lease complete" it spits a (MAC address, hostname, broadcast domain) tuple over to the IPv6 side. The broadcast domain plus configuration yields a list of prefixes, and the MAC address gets turned into a SLAAC host-identifier. The two make a set of putative addresses. The state machine then sends an ICMP6 echo request to each putative address and if it responds then that address is added as an AAAA record with the hostname.
There are some implementation details involving timeouts and retries and sending speculative router advertisements to ensure that a new-on-the-network host is ready to reply to the pings. The practice is that it always works, even a smartphone moving slowly into a dodgy Wifi network. If the client can get a DHPCv4 lease, the IPv6 SLAAC address gets a name too. Simon. _______________________________________________ homenet mailing list homenet@ietf.org https://www.ietf.org/mailman/listinfo/homenet
