Hi, On Jul 12, 2010, at 6:01 PM, Mathilde Durvy (mdurvy) wrote:
> Hi Zach, > > Thanks for clarifying the example, I was just going through the same > exercise myself and I have a couple of questions: > - In the NS, why not use "SLLAO: short" since the ARO already carries the > IEEE. This would avoid to use an additional refresh NS to establish the > mapping "GP16 / short" You could if that short-address would have been e.g DHCPv6 or otherwise assigned. In this example the short address is randomly generated - too dangerous to start using that as your MAC address before knowing if it is a duplicate. > - Also concerning the processing of the RS and the draft says: > "A Router Solicitation might be received from a host that has not yet > registered its address with the router. Thus the router MUST NOT > modify its Neighbor Cache with the SLLA option from the Router > Solicitation. The SLLA option is only used to form the link-layer > address to which the router sends the Router Advertisement." > I'm not sure I understand the last sentence. Isn't the IPv6 DST of the RA > the IPv6 SRC of the RS. Then a temporary, "neighbor cache" entry "source RS > / SSLAO RS" would be needed to establish the mapping with the layer 2 > address, no? You are correct, but we don't call that a temporary neighbor cache entry as it doesn't go into the neighbor cache. In the example I gave the source address is an EUI-64 based link-local so it would be safe to make an entry - but that might not always be the case. > - Similarly upon receiving a RA the host should install a neighbor cache > entry for the router. Is there a lifetime or other information associated > with this entry? Correct. I would assume that this follows normal RFC4861 behavior for default routers? Zach > > Best, > Mathilde > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Zach Shelby > Sent: lundi, 12. juillet 2010 16:27 > To: 6lowpan 6lowpan > Subject: [6lowpan] ND exchange example > > I made an example of a 6lowpan-nd bootstrapping exchange for an 802.15.4 > device bootstrapping for the first time, generating a 16-bit address, and > then registering it in an unmanaged network. ZigBee IP is trying to minimize > the number of addresses each node has to configure - the goal is to use just > LL64 and GP16. LL64 is avoided where possible though as it has 6 bytes of > extra overhead per address. > > Below the suggested example uses GP16 for RS/RA and NS/NA exchanges where > possible. LL64 is used more for bootstrapping before the GP16 is confirmed. > A couple questions come up here: > > 1. Can we make an exception for using global addresses for RS/RA and NS/NA > between the host and router? RFC4861 requires the use of link-local. Using > GP16 would save some complexity and overhead. > > 2. Is the L2/L3 address setup of the initial NS/NA exchange too messy (see > Ticket #87)? We are mixing 64-bit MAC addresses with GP16s for the source of > the NS and the destination of the NA. This means those addresses can't be > compressed by 6lowpan, but then again we save the Registration Address field > from ARO... Is any change needed here or can we live with the proposed > solution in Ticket #87? > > > RS from joining device > > MAC src: IEEE > IP src: LL64 > SLLAO: IEEE > MAC dst: Broadcast > IP dst: All-routers Multicast > > RA from parent router > > MAC src: Short > IP src: GP16 > SLLAO: Short > MAC dst: IEEE > IP dst: LL64 > > Initial NS from joining node > > MAC src: IEEE > IP src: GP16 (tentative) > SLLAO: IEEE > MAC dst: Short > IP dst: GP16 > > (Note: parent router stores no L2 state about the tentative address, carried > in the SLLAO to the 6LBR and back) > > Initial NA from parent router (success) > > MAC src: Short > IP src: GP16 > MAC dst: IEEE (Copied from the SLLAO of the NA from the 6LBR) > IP dst: GP16 (tentative) > > (after this point the LL64 isn't really used anymore) > > Refresh NS > > MAC src: Short > IP src: GP16 > SLLAO: Short > MAC dst: Short > IP dst: GP16 > > Refresh NA > > MAC src: Short > IP src: GP16 > MAC dst: Short > IP dst: GP16 > > > -- > 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 -- 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
