> I know; I'm asking about what's intended. When DHCP starts normally, > the interface is "down" and DHCP marks it as "up" so that it can do > its thing. I'm really asking about when DHCP knows it ought to do > that and when it should leave the administrator's IFF_UP flag (or lack > thereof) alone.
I see. For IPv4, we could pass a flag to open_ip_lif() telling it whether this is the initial bringup of the interface (due to the administrator issuing a "start") or a subsequent restart (due to expiration or DAD). It could then leave the IFF_UP flag as-is in the restart cases. For IPv6, it appears the code does not have any special IFF_UP handling for the link-local and just assumes it's IFF_UP, so I think it's unaffected. > Yep. Though I'd say that "unplumb" is the only clear unrecoverable > there. Even with an address change, *I* would have expected DHCP to > ignore the change on the interface itself entirely unless (and until) > the server decided to supply a different address. > > In other words, change of lease data from the DHCP server means "apply > these changes now to the system." But otherwise DHCP isn't in the > business of trying to make sure that the interface matches what's set. > It's a configuration mechanism, not a nanny. Hmm, I'm not sure about this, but I also don't think this case is too important to the core topic at hand. -- meem
