On May 9, 2010, at 9:41 AM, Pascal Thubert (pthubert) wrote: > Hi Richard > > >>> The flow label helps the router select the instance for a packet. >> >> "Helps"? Doesn't the flow label tell the router exactly which > instance to use? > > At the moment you're correct, it's one to one. I've heard voices (was > that Kris and Phil?) asking for a more complex stateful mapping at the > RPL network ingress, and a new field in the new RPL option for the > instance. My vote is to leave the instance ID in the flow label where it > is today, since it is end to end application data. While I agree that > the loop avoidance data fits very well in a hop by hop option long as > the option stays contained in the RPL network. Which is what Jonathan's > draft does for all I understand so I'm fully happy there.
Pascal, I still don't understand how this could possibly work. I'm an application on the Internet. I want to send packets to a RPL node. How am I supposed to set the flow label? You are assuming an out-of-band communication mechanism to set the label. This requires a sender to know that the endpoint is a RPL node; does this really seem like a good idea? Instance IDs MUST work when a sender does not know the destination runs RPL. RPL therefore MUST solve the case where the sender does not set a flow label. Otherwise only nodes that are aware of RPL and can determine the instance ID can communicate with RPL nodes. This does not seem like a good idea to me... The current proposed mechanism is that there is an optional RPL IPv6 header that specifies the instance ID. If that header is not present, then RPL can assume the instance ID is in the flow label. Phil _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
