Jen Linkova <furr...@gmail.com> wrote: >> I didn't really understand 2.2.2: is it exploiting some corner case in the >> spec, or maybe just some part I am not well clued in about. So maybe an >> extra paragraph to explain things.
> It's just using the standard ND process: when the node B receives an > NS from node A and that NS contains the node B address as a target > address and SLLAO contains node A LLA, > the node B would respond with NA and would create a STALE entry for > the node A - https://tools.ietf.org/html/rfc4861#section-7.2.3 I read through https://tools.ietf.org/html/rfc4861#section-7.3.3 and it says: The first time a node sends a packet to a neighbor whose entry is STALE, the sender changes the state to DELAY and sets a timer to expire in DELAY_FIRST_PROBE_TIME seconds. If the entry is still in the DELAY state when the timer expires, the entry's state changes to PROBE. If reachability confirmation is received, the entry's state changes to REACHABLE. Upon entering the PROBE state, a node sends a unicast Neighbor Solicitation message to the neighbor using the cached link-layer address. While in the PROBE state, a node retransmits Neighbor Solicitation messages every RetransTimer milliseconds until reachability confirmation is obtained. Probes are retransmitted even if no additional packets are sent to the neighbor. If no response is received after waiting RetransTimer milliseconds after sending the MAX_UNICAST_SOLICIT solicitations, retransmissions cease and the entry SHOULD be deleted. Subsequent traffic to that neighbor will recreate the entry and perform address resolution again. Is PROBE and DELAY different states? It almost feels like a typo here. >> I kinda like the ping all routers trick. > I think it's a hack ;( we do have a mechanism for communicating > neighbours addresses/reachability called ND. It would be nice to > utilise its machinery. > Pinging creates additional overhead on routers and could get filtered. > But I'd not be surprised if it's the only way we have realistically to > mitigate the issue.. Yes, it's a hack. It leverages existing behaviour, can be deployed unilaterally by mobile phone makers, and does not require any new state in the end device, as they don't even have to listen for the ECHO REPLY. Let me suggest a different hack: use stateful DHCPv6. -- Michael Richardson <mcr+i...@sandelman.ca>, Sandelman Software Works -= IPv6 IoT consulting =-
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