Data packets waiting for a route (i.e., waiting for a RREP after a
RREQ has been sent) SHOULD be buffered. The buffering SHOULD be
"first-in, first-out" (FIFO). If a route discovery has been
attempted RREQ_RETRIES times at the maximum TTL without receiving any
RREP, all data packets destined for the corresponding destination
SHOULD be dropped from the buffer and a Destination Unreachable
message SHOULD be delivered to the application.