In addition to the current tickets for nd-09, an issue was brought up on the ZigBee IP list that we should discuss.
When using a 16-bit IEEE 802.15.4 address generated at random (or manually) with the nd-09 address registration procedure, how can one detect if the address was checked for duplicates locally or across the LoWPAN? In order for a host to safely start using a short address generated like this it must know that it is unique throughout the LoWPAN. Then upon failure the host can either generate and try to register a new address or fall back to using an EUI-64 derived address. The current draft simply returns either Success or Duplicate Address codes. The Success code doesn't tell a host if Section 8.2 (or some other technique) has been used to perform DAD by the 6LR. We think there is a need to clarify this situation for addresses where a check for LoWPAN uniqueness is required. DAD may not be performed for multiple reasons, a 6LBR may not be reachable, Section 8.2 might not be supported or it may just fail. I see two possible solutions if we agree this is a problem: A. Include a "DAD Required" flag in the ARO message sent by the host. If the 6LR is not able to perform DAD, then it returns an error code something like "DAD Unavailable". This DAD Required flag also makes it easier for the 6LR to determine if an address was assigned by DHCPv6 already thus not requiring DAD. B. Include a new Success code so that there are two, allowing for a host to determine the extent to which a duplicate check was made. - Success and address checked for local uniqueness (0) - Success and address checked for LoWPAN uniqueness (1) Thoughts? Zach -- Zach Shelby, Chief Nerd, Sensinode Ltd. http://zachshelby.org - My blog "On the Internet of Things" http://6lowpan.net - My book "6LoWPAN: The Wireless Embedded Internet" Mobile: +358 40 7796297 _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
