1. if node i has no downstream links and RRi is unset, it rebroadcasts the QRY message
and sets RRi.
2. if node i has no downstream links and RRi is set, it discards the QRY packet
3. if node i has at least one downstream link and its height is NULL, it sets its height to
Hi = min{Hj|j ∈ Ni} + {0, 0, 0, 1, 0} and broadcasts an UPD packet
4. if node i has at least one downstream link and its height is non-NULL, and if a UPD
packet has been broadcast since the link over which the QRY packet was received
became active, it discards the QRY packet. Otherwise it broadcasts an UPD packet.
Also, if RRi is set when a link becomes active, it broadcasts a QRY packet