Le 25/10/2012 15:52, Michael Richardson a écrit :
ralph> Why wouldn't RPL be used for such networks? It has built-in PD for ralph> dynamic networks, if I understand it correctly, with RA used at the ralph> subnet level. Alexandru Petrescu <alexandru.petre...@gmail.com> wrote: AP> RA used to exchange routes - if this is what you mean, and yes it may be AP> used by RPL (last time I read it). AP> If the question is about this, then I think it is pertinent. One may AP> imagine a way to use RPL on the MRs for that purpose. AP> However, I doubt RPL can Delegate Prefixes (in the pure sense of Prefix AP> Delegation). RPL doesn't do this in protocol, but then, neither does ND. I wouldn't extend RPL to do this, however, I'd send a DHCPv6 PD format message. It can be a single exchange, and nobody said a single program can't speak multiple protocols.
Yes, but consider that DHCPv6-PD is already used in a rather complicated way on the MR of an IV (Internet Vehicle). It is used according to rfc6276, to obtain a prefix from home. In that it is specified that MR should be both a Requesting Router and a Relay for that tunnel interface. On another hand, if the MR of LV requests a Prefix from the IV's MR then this latter should also be a Relay, but on a real interface as well. One ends up with two Relay software on the same machine. I am afraid this is next to impossible to configure with some existing software.
But, I question whether one always needs to get address space, vs announce it. I don't know the answer: it really depends upon who your second vehicle needs to talk to, and why it thinks that vehicle one (and vehicle one's ISP) is willing to give it bandwidth.
I think both tools of announcing address space, and obtaining address space, should be available to vehicles, and applied depending on whether the communication is between two vehicle devices only, or not, whether the infrastructure is available, or not. It is viable that an LV self-configures ULAs based on VIN and announces them only to vehicles nearby (not to infrastructure). It is viable that an LV to get globally routable address space from an IV.
If you don't want to speak RPL, then you need to pick the TBD homenet-routing-protocol. We don't need a third.
Needing a third or not - I don't know. But picking homenet protocol, or RPL for vehicles would probably involve a large change in requirements of either. Alex
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