On Oct 12, 2009, at 1:09 PM, Zach Shelby wrote:
On Oct 12, 2009, at 23:01 , Jonathan Hui wrote:
1) Assuming that link-layer addresses can always be computed from
IIDs. While this assumption can remove the need for NS/NA for
address resolution, the implication is that the IIDs are limited to
the link-layer addresses in use. 802.15.4 radio hardware is
typically limited to one short and one extended address at a time
and that limits the number and structure of IIDs that can be
assigned at any time.
Actually this is not true anymore in nd-06. Based on feedback in
Stockholm, we relaxed the IID-MAC mapping assumption. If you have a
LoWPAN that for some reasons assigns an IID that requires address
resolution, this can be performed on the host-router interface.
That's great, but can you explain how a node determines whether or not
it needs to perform address resolution? I wasn't able to find how in
draft-06.
2) Using NR/NC exchanges to provide NUD. With the current draft,
NR/NC exchanges only maintain reachability information for the link-
local address of the attachment router. However, NR/NC exchanges,
as defined, cannot provide reachability information for global
addresses. Additionally, NR/NC messages cannot be used to maintain
reachability information for neighboring hosts (not routers).
Good example. If this is really a problem we can look at ways to
improve that of course. I don't follow you on why they can't provide
reachability info for global addresses (from Address Options) - but
let's talk about that separately.
Testing reachability is traditionally done by actually using the
target address to send messages. Using the address options only tells
you that the node *thinks* they are assigned to the interface - it
does not test that communication
is actually possible when using the target address.
I'm not convinced that these are the only examples that we need to
be aware of with the existing draft. I'm also not convinced that
enough people have weighed in on the examples above to say that
such implications are OK
This is exactly what last call is for ;-) Forcing everyone to
actually read the thing again, and to make constructive comments.
I was trying to encourage people to spend the extra cycles by raising
some issues I'm aware about, irrespective of whether or not the draft
is in WGLC.
--
Jonathan Hui
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