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On Oct 14, 2009, at 1:27 , Colin O'Flynn wrote:
Hi Jonathan,I agree with you there - these nodes would *not* be participating in real IPor mesh forwarding.
Right, not all nodes are routers. We do have the concept of a host, and it is a useful one also in LoWPANs.
However the ND process needs to function with these nodes. If we rely on 4861, these nodes which are going to miss packets must have a way to defendtheir address!
Jonathan is assuming the link provides a service guaranteeing nodes within radio range can communicate within some bounded latency using duty-cycling or other techniques. This is an assumption you may be able to make. But if you do that then routers may need to answer on behalf of hosts as those hosts may be sleeping asynchronously to eachother if the router is e.g. powered.
It is safe to assume that there is synchronization on the host-router and router-router interfaces - OK. It is not safe to assume synchronization between peer hosts attached to the same router. Nor between different sections of a LoWPAN. No, we are not trying to solve DTN.
Zach
-Colin -----Original Message----- From: Jonathan Hui [mailto:jhui at archrock.com] Sent: October 13, 2009 11:04 PM To: Colin O'Flynn Cc: 'Adam Dunkels'; '6lowpan' Subject: Re: [6lowpan] Fundamental concerns about 6lowpan ND Hi Colin, On Oct 13, 2009, at 2:56 PM, Colin O'Flynn wrote:My concern for this sleeping method is very low power nodes. These would be parasitic nodes for example that can only wake up every few seconds at most. These super-low power nodes could not listen continuously. Forcing them to require waking up would basically eliminate them from the picture.For these very special devices, I often prefer to view them as wireless peripherals rather than IP devices. They most likely won't be able to participate in forwarding/routing functions. Any bi- directional communication tends not to be end-to-end since they want to minimize round-trip time. -- Jonathan Hui _______________________________________________ 6lowpan mailing list 6lowpan at ietf.org https://www.ietf.org/mailman/listinfo/6lowpan
-- 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, FINLANDThis e-mail and all attached material are confidential and may contain legally privileged information. If you are not the intended recipient, please contact the sender and delete the e-mail from your system without producing, distributing or retaining copies thereof.