Thomas Heide Clausen a écrit :
Zach,
Thanks for Cc'ing [autoconf]. We're pleased that the document also is
applicable in [6lowpan].
On Nov 14, 2009, at 4:30 AM, Zach Shelby wrote:
Alex,
(added autoconf to CC)
Now I see what you were concerned about below. Yes I agree, the
wording of how we assign addresses is slightly different. We are using
host-based routes with exact match. As the autoconf document uses a
SHOULD here, 6lowpan-nd can still use a /64 advertised throughout the
LoWPAN to form addresses. It would be nice if autoconf could update
their wording somewhat, so let's see if that is possible.
One of the comments from [autoconf] this time was to adopt a phrasing of
"has no on-link prefix", as suggested by Dave Thaler, Sit tight, I think
that an updated I-D should be forthcoming shortly.
Thomas, Dave - what do you mean by "on-link" prefix? What do you mean
by "link"?
"on-link" prefix is understood in settings where "link" is understood.
Settings where "link" is not understood, "on-link" makes no sense
whatsoever, as "off-link" doesn't either.
Alex
Zach, if you have any additional comments, please do raise them also on
[autoconf].
Thomas
Some comments below.
On Nov 13, 2009, at 19:01 , Alexandru Petrescu wrote:
Zach Shelby a écrit :
On Nov 12, 2009, at 18:17 , Alexandru Petrescu wrote:
We do appreciate all the help you gave to polish our model in
April, thanks for that!
And now you're about to remove the link definitions - thanks for
thanking me.
We didn't say that we are going to remove all references to a link.
We haven't decided how to use the autoconf model yet. Obviously we
would need to build around it.
Additionally to AUTOCONF draft being against the 6lowpan-ND
definition of link, and of its first phrase in the Bootstrapping
section (are you going to remove that too?), AUTOCONF draft also
requires the prefixes to be /128 exclusively. Are you thus going
to require /128 prefixes exclusively too in the 6lowpan-ND document?
As a LoWPAN shares a single prefix, all nodes in a LoWPAN can have is
a an address.
YEs - that shared single prefix is a /64 with IPv6 over 802.15.4,
because that's what rfc4944 suggests.
And yes, each node in a LoWPAN has an address.
Or, AUTOCONF draft-ietf-autoconf-adhoc-addr-model-00 says this:
o A subnet prefix configured on this interface should be of length
/128.
I think we either have a terminology problem (what's a "subnet prefix
configured on an interface"?) or a crystalizing incoherency between
AUTOCONF and 6lowpan-nd.
My suggestion, along the way I understand these WGs landscapes, please
modify the AUTOCONF document to no longer suggest that /128 prefixes
assigned to interfaces that way.
If AUTOCONF means "host-based routes" by that "subnet prefix configured
on an interface should be /128" then AUTOCONF please use "host-based
routes" instead in the AUTOCONF recommendations.
AUTOCONF please note that 6lowpan-ND document touches briefly on these
host-based routes aspects when talking "exact match" searches in its
6LoWPAN Terminology section, and please don't remove that from the
6lowpan-ND document.
The "exact match" method of search in a routing table (as opposed to
"longest-prefix match") is terminology similar to "Basic Match" and
"Longest Match" used in rfc1812. Although the rfc is only IPv4 it
also applies to IPv6.
It is however not quite the same thing.
When you want, we can discuss the definition of "exact match"
further, as useful to implementer. The 6lowpan-ND definition of
"exact match" is a good start, IMHO.
We do not talk about assigning prefixes to nodes in this WG.
YEs, right.
AUTOCONF doesn't talk either: they recommend the assignment of a /128
prefix to an _interface_ (not a node).
I meant interface of course (we usually just have one)...
Or, 6lowpan-ND does assign a prefix to an interface when doing the
IPv6-over-802154 SLAAC stuff.
Not exactly. We only use the advertised /64 to form the address. After
that we assume everything (except link-local) is off-link. Therefore
we don't really assign the prefix to the interface. So in practice the
end result is the same as assigning a /128. Right? So this is just a
wording difference.
Routers do advertise the prefix used throughout the LoWPAN (using
RAs). And nodes may then auto-configure addresses based on that.
YEs, and the auto-configured addresses look like this:
2001:db8::XXXX:XXXX:XXXX:XXXX/64
Note the "/64".
So the autoconf text should say that you can should a /128 or a /64
when using SLAAC to make that explicitly OK?
Zach
Alex
Are you going to modify the 6lowpan-ND bootstrapping because
AUTOCONF draft requires prefixes /128?
It already works like this, no changes necessary. As far as I can
tell, the autoconf draft requires no functional changes to the base
mechanisms of our work. Again, we still need to look at the details.
Cheers, Zach
--
http://www.sensinode.com
http://zachshelby.org - My blog “On the Internet of Things”
Mobile: +358 40 7796297
Zach Shelby
Head of Research
Sensinode Ltd.
Kidekuja 2
88610 Vuokatti, FINLAND
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