dhcpcd-discuss

Hi Harald

On 2016-12-19 13:30, Harald Albrecht wrote:
> Hi,
>
> I want to realize kind of a "stand-alone" mode on a Raspberry Pi IPv6
> router. The RasPi IPv6 router can work either (1) as a cascaded
> router, where it asks its upstream delegating router for IPv6 prefixes
> and assigns them to its own downstream interface(s). When there is no
> upstream connection, the RasPi should switch to (2) stand-alone mode:
> it then should configure its downstream interface with a static ULA
> prefix. However, as soon as there is an upstream router coming back
> and delegating a prefix, the ULA prefix should be removed from the
> downstream interaces.
>
> When looking through hook scripts and dhcpcd sources I've noticed the
> DELEGATED6 hook $reason, but this covers a new lease, or a dropped
> lease on a downstream interface. When there hasn't been any delegated
> prefix before, this would not trigger (at least that's my limited
> understanding here). In addition, I cannot assume that there is an
> old, still valid lease.
>
> I've seen the syslog timeout notice that dhcpd sends after its initial
> leasing attempt has been failed. But there does not seem to be a hook
> reason for this? Or did I miss it?
>
> Of course, any help here greatly appreciated! And finally, thank you
> very much for dhcpcd!

Is there a reason why the two addresses cannot exist at the same time?
See RFC5220 2.1.4 - https://tools.ietf.org/html/rfc5220#page-7

There currently is no hook script for DHCPv6 timeouts because DHCPv6 is 
wholey reliant on a functioning IPv6 router brodcasting it's RA where-as 
DHCPv4 is fully self supportive.
Also see the recent thread here about Is "--lastleaseextend -p" expected 
to work for IPv6 as well? in the archvies.

DELEGATED6 is only run on downstream interfaces as you have correctly 
noted.

Roy