[DNA] Couple of points on draft-jinchoi-dna-soln-frame-00.txt

[Alper Yegin <alper.yegin@samsung.com>]

Hello,

Few comments on this I-D...

   If a link change has occurred, a host assumes that its IP
   configuration is no longer valid.  It needs new default router and IP
   address.  If it remains at the same link, a host assumes its IP
   configuration is still valid.

I think the delay between the time the host last used the particular
configuration and the time it thinks the same applies to the newly
attached link should be taken into consideration. This time is
relatively short when we are simply comparing the pre-handover link with
the post-handover link. But given that a configuration has a lifetime
(based on prefix lifetime, or DHCP lease time), the same mechanism could
be applied when the delay is higher but still bound by the lifetime.
This might be because the host has visited some other links in between. 

When we do that, there is a problem. During the host's absence, some
other host might have acquired the same IPv6 address. This is possible
with stateless address autoconfiguration [low probability, can we ignore
it?]. In theory, this should not be possible with the DHCPv6 because the
address is reserved for the host during lease time, but I heard there
are DHCPv4 products out there that do not observe this [maybe this would
not be a problem for IPv6].  

Anyways, my point is that there are some additional considerations if we
want to say I can use the same configuration on the same link as long as
it hasn't expired.


   Either an AP (which implements [14]) immediately sends an RA to the
   host, or the host sends an RS to all-routers and one or more routers
   on the link responds to the RS with an RA.

The other possibility is that the access router sends an unsolicited RA
to the host upon detecting the new attachment. For that the access
router needs to receive the link up, and that might require some
additional protocol work when L2 access point is not co-located with the
access router(s).


  2.  We assign each link a locally unique Link Identifier.  'Locally
      unique' means, no two adjacent links have the same Link
      Identifier.

This would have issues if the hosts ever make a long jump (skipping some
intermediate links) for any reason.

Alper