In figure 2, nodcs Band C arc in the range of A and all the
nodes broadcast the HELLO message to each other. When A
receives a HELLO message it sets the periodic timers for the
next reception of the HELLO messages from Band C. Now. A
has received the HELLO message from C for the second time
before the timer for C expires and hence it resets the timer for
C. But A has not received the HELLO message from B before
the timer expires. Hence A will assume that B is out of range
and removes B from its table.
There is a probability that B is still in the range of A and
because of poor link quality between A and B, A has not
received the HELLO message.