You may have thought of this one: The MAC address filter table could be totally confused
about the source device’s location because the switch can receive the frame from
more than one link. Worse, the bewildered switch could get so caught up in constantly
updating the MAC filter table with source hardware address locations that it will fail
to forward a frame! This is called thrashing the MAC table.
uu One of the most vile events is when multiple loops propagate throughout a network.
Loops can occur within other loops, and if a broadcast storm were to occur simultaneously,
the network wouldn’t be able to perform frame switching—period!