On 02/07/2014 0:35, Fernando Gont wrote:
Hi, Roy, On 06/12/2014 04:19 AM, Roy Marples wrote:Even if addresses are allocated from a pool, I want a system to (usually) havethe same address after a reboot. Even when the shutdown sequence gives upthe DHCP lease.What we are talking about here is part of the RA/RS protocol. DHCP is separate still in IPv6. The prefix in the RA has a flag to say "create an an automatic address for this prefix". This discussion is about changing the hardware element of the address into a stable private stateless one, generated by the host. The latest dhcpcd code also uses the same logic to generate stableI'm a bit confused. You've implemented RFC7217 for SLAAC, and have also "ported" the same algrithm to DHCPv6?
DHCPv6 doesn't use SLAAC directly.However, it does rely on a link-local address assigned to the interface which is SLAAC generated.
private LL addresses as well, provided it beats another operation bringing the interface up at boot time (like say wpa_supplicant or ifconfig).Would you mind elaborating a bit more on this one?
Sure. When dhcpcd starts up it scans for interfaces it can use. For each interface it adds the currently known addresses to it.When dhcpcd decided to start IPv6RS or forced DHCPv6 on an interface it consults it's list of known address for a link-local address.
If none found, it will add one using SLAAC. Then it will UP the interface and continue on it's merry way. BSD kernels will only add a link-local address on UP if none present.Linux kernels will add one regardless, but actually use the 1st one assigned (from my testing anyway). As this is a kernel operation, it's quite possible for another userland application which UPs the interface to do this before dhcpcd does it. Because if this, I added a toggle to NetBSD sysctl to stop the kernel from doing this - other BSD and Linux have the same toggle.
Thanks Roy