Robert
Robert Cragie (Pacific Gas & Electric) Gridmerge Ltd. 89 Greenfield Crescent, Wakefield, WF4 4WA, UK +44 (0) 1924 910888 http://www.gridmerge.com <http://www.gridmerge.com/> Jonathan Hui wrote:
For many of the same reasons, early versions of the improved hc draft (before it became a WG doc) did not make use of the PAN ID to create an Interface ID and left it to all zeros. If you really wanted something other than all zeros (e.g. the 'symbolic' PAN ID), then use context information with a longer prefix to indicate what those non-zero bits are.Including this within the next rev of 6lowpan-hc is worth discussion. It certainly is related, but not limited to HC.-- Jonathan Hui On Mar 5, 2010, at 7:39 AM, Colin O'Flynn wrote:Hello, Hmm, makes sense to me. Would it be possible to get a recommendation in hc-06 before WGLC, or where else would it make sense? As it's difficult to use hc06 with 16-bit addresses unless you decide on which way this will work. Regards, -Colin -----Original Message----- From: Richard Kelsey [mailto:[email protected]] Sent: March 5, 2010 2:39 PM To: Colin O'Flynn Cc: [email protected] Subject: Re: [6lowpan] 6lowpan 16-bit PAN-ID FieldFrom: "Colin O'Flynn" <[email protected]> Date: Thu, 4 Mar 2010 22:59:22 -0000 RFC4944 has the quote:First, the left-most 32 bits are formed by concatenating 16 zero bits tothe16-bit PAN ID (alternatively, if no PAN ID is known, 16 zero bits may beused). This produces a 32-bit field as follows:How does a receiving node know if zero's have been used there to recreatethe IP addresses? Unless I'm missing something, this seems to be aambiguouscase. It seems unlikely a node will know it's short address but notPAN-ID. I am not sure what to make of this either. The PAN ID may change if a PAN ID conflict is detected, in which case it would be a nuisance if all of the interface IDs had to change. To me, the only time where it might make sense to to use the PAN ID in the interface ID would be if a lowpan was spread across multiple PANs that did not coordinate 16-bit address assignment. Even in that case, it would be better to use a 'symbolic' PAN ID in the interface IDs, to avoid the need to change later. In a lowpan With only a single PAN ID it makes much more sense to use zeros and avoid problems if the PAN ID has to change. -Richard Kelsey _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan_______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
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