Re: [DNA-BOF] Attachment Detection charter text for discussion

[Bernard Aboba <aboba@internaut.com>]

> Perhaps my wording is not so good after all.  I simply meant that
> "network attachment" occurs when an interface becomes active on a
> link instance.

What does "active" mean?  When the interface senses carrier? Or when all
tasks necessary to make the interface ready for L3 connectivity are
completed (e.g. L2 authentication & association, etc.)

> How that is detected is the work of DNA.

It may not be easy to "detect" at L3 when the interface has
not yet entered an L2 state in which L3 connectivity is possible.  If the L2 state is
unauthenticated, it can look to L3 like there is no connectivity at all,
leading to all kinds of poor decisions, such as allocation of an IPv4
Link-Local address.  Without L2 "hints", the host will not receive an RA,
and may attempt to test reachability to the default gateway or send an RS,
all to no avail.  By the time that the L2 state is truly usable, the
interface state may have been backed off considerably.

So if we are looking for robustness against bogus L2 "hints" we need to
consider bogus "link up" hints as an important example in that category.