Reddy, Joseph a écrit :
Hi Pascal,
The proxy-ND that you described from the draft may not always
work....consider the case where a backbone node attempts to "ping6" a
6lowpan node.
To the backbone node, the 6lowpan devices appears as "on-link" since
the ER responds with NS on behalf of the 6lowpan device. This will
cause the backbone node to communicate with the 6lowpan device using
its link-local address as the source address. Then the 6lowpan device
has no way to respond back to the backbone node since it only knows
the link local address and not the global address of the backbone
node ( unless 6lowpan routers can forward packets with link-local
destinations ). Did I miss something here ?
I agree with this example of the other node on backbone using its
link-local address to talk to the lowpan node.
I also agree ER should not forward packets having src or dst fields an
IP link-local address.
Moreover, it is not clear to me from the draft what kind of "proxy" ND
is performed. If it is similar to what the Mobile IPv6 rfc3775 HA does
then is it for lowpan node's IP link-local or global address? Anyways,
it will not help detecting a collision of the short MAC address of the
lowpan nodes of different ERs' lowpans. Even if it did, it would have
no means to change that.
It's strange to see proxy-ND used to detect duplicated addresses.
Alex
-Regards, Joseph
------------------------------
Date: Tue, 17 Nov 2009 18:36:37 +0100 From: "Pascal Thubert
(pthubert)" <[email protected]> Subject: Re: [6lowpan] Thoughts on
draft-ietf-6lowpan-nd-07 To: "Colin O'Flynn" <[email protected]>,
"Carsten Bormann" <[email protected]>, "Alexandru Petrescu"
<[email protected]> Cc: 6lowpan <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="us-ascii"
Hi Colin:
I think you're describing the draft. Basically the edge router does
proxy-ND over the backbone. So if a node on the backbone looks up a
6LoWPAN device, the edge router answers NS with NA on behalf of the
device. So the node sends packets via the edge router. The edge
router forwards back to the device over the lowpan. As you figures,
this is why the device needs to periodically maintain the binding
with the edge router.
This is somewhat similar to mobile IPv6 though there's no tunnel.
Pascal _______________________________________________ 6lowpan
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