Hi Giorgio: Please see inline
>>>http://tools.ietf.org/html/draft-thubert-6lowpan-backbone-router. ... >>>So, what do you think? >In my opinion it's a very good draft and I agree it would be a good >idea to try to reduce broadcast traffic for ND. > >For this reason, the "white board" approach is very appealing, but I have some questions about it... >Tell me if I'm wrong: the main idea is that there is a logical >centralized "white board" that includes all the IP addresses from multiple PANs. [Pascal] Right; but there can and should be multiple backbone routers interconnected by a backbone, thus the name. Because the second half of the BbR feature is ND-proxy so that any node on the backbone is virtually on the same link as any device behind a BbR. > >But what happens within a PAN when a backbone router crashes? How can a >node get routing info about other nodes belonging to its same PAN if it >can't access the white board residing on the crashed backbone router? >The nodes may keep their own routing cache, but this is not a completely reliable approach. > [Pascal] When the BbR crashes, that's mostly the same as if you are a mobile node and your MIP6 Home Agent crashes. Active (similar to MIP6 route optimized) connections with the PAN are maintained, conections to the outside (similar to via the HA) are dropped. New connections with unresolved MAC addresses can not be started, and new nodes can not be inserted. That was acceptable for RFC 3775, I guess that is still. There's ample space for HSRP/proprietary hot standby solution for backup when needed. >Is that point interesting for the WG? (maybe is out of scope of this >specific draft) Let me know if you have any thoughts about this (or if >this problem it's been yet analized by the WG :p) > [Pascal] Well, we are supposed to consider how to implement ND in a LoWPAN. BbR is a ND solution that adds the concept of backbone to the picture. That concept comes from real users feedback and we should not ignore it... Pascal _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
