The self-echo guard registered a packet's hash and forwarded path when the
engine decided to forward it and kept it for 30 s. Two things could then
hide a real neighbour from the link tracker:
- A neighbour whose 1-byte path hash collides with ours, repeating the
same packet from the same upstream path, carries exactly the path we
would have sent.
- The registration happened before the duty-cycle gate, so a packet that
was never transmitted still suppressed matching receptions.
Registration now happens at the physical send, inside the TX lock after
the duty-cycle gate, and records which radio is sending. A send that
fails is forgotten. A reception counts as our echo only when it arrives on
a radio other than the one that sent it, and while that send is on the
air or within 2 s of it finishing, which covers a remote modem's delivery
delay. Single-radio nodes keep no records at all, since a lone radio
cannot hear itself.
A colliding neighbour is now mistaken for our echo only if it repeats the
same packet on the same path, on the other radio, inside that window.
agessaman
a37be4b2f7