On Oct 14, 2009, at 2:24 PM, Richard Kelsey wrote:
I have generally found 802.15.4 ACKs unhelpful for NUD. There a lots of ways in which an ACKed packet can fail to reach the higher layers. For example, any kind of MAC security confusion can cause packets to be ACKed but otherwise ignored.
Same experience here.
What has worked for NUD, between routers at least, is relying on link quality measurements. In the systems that I have used each router periodically informs its neighbors of its own link quality estimates in order to detect asymmetric links. This has the side effect of removing any need for NUD above the link layer. In summary, I think that 1-hop NUD is important, but that it doesn't necessarily have to be done at layer 3.
I don't see an appreciable cost difference in utilizing raw link, 6lowpan, or IP messages - especially for link-local communication.
Changing the semantics of an 'ack' will certainly help NUD if you use unicast probing to achieve it.
-- Jonathan Hui _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
