Quick answers: On Nov 16, 2009, at 06:43, Ralph Droms wrote:
> 1. In a mesh-under network, the L2 characteristics of the lowpan are > close to those usually assumed for implementation of IPv6; in > particular, there are no "lowpan routers" at L3 and L3 messages *can* > be delivered (perhaps with lower probability of success) directly > between lowpan nodes. Why is ND not sufficient in this model? RFC 4861 ND works in a pure RFC 4944 mesh-under network if: 1) the mesh-under (L2) routing protocol provides subnet-wide multicast, 2) that is efficient enough to be used for routine ND messages, 3) nodes are awake often enough to detect and reply to NS messages. Such networks do exist, but these assumptions are not necessarily compatible with many application scenarios we have in mind; this is the reason we started with ND optimizations. > Would > proxy ND be sufficient? I haven't seen such a design yet, so I don't know. > 2. In a route-over network, all nodes are routers That is not the assumption: The assumption is that there are hosts and routers, and that the forwarding function is performed by the routers. There needs to be a protocol that enables hosts to register themselves to routers, independent of the routing protocol. Since the host-router relationship is somewhat ephemeral due to the nature of the wireless links, address assignment needs to be lowpan-wide instead of per host-router relationship. As ND-07 is not by itself supporting host-host communication, address resolution only happens between hosts and routers. Re one other term: "relaying" is the term ND-07 is using for what routers do between themselves to process host NR messages; it is not IP forwarding. It is probably more appropriate to give the inter-router message a different name (e.g., relayed NR, RNR), so the confusion between this relaying process and IP forwarding is reduced; this is the part that will move to the second document after the split. Gruesse, Carsten _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
