If a switch is working in the fail-open mode, what will happen when the switch’s CAM table fills to capacity and a new frame arrives?
A.
The switch sends a NACK segment to the frame’s source MAC address.
B.
A copy of the frame is forwarded out all switch ports other than the port the frame was received on.
C.
The frame is dropped.
D.
The frame is transmitted on the native VLAN.
Explanation:
A Cisco Catalyst switch uses a Content Addressable Memory (CAM) table to store the
information used by the switch to make forwarding decisions. Specifically, the CAM
table contains a listing of MAC addresses that have been learned from each switch port.
Then, when a frame enters the switch, the switch interrogates the frame’s destination
MAC address. If the destination MAC address is known to exist off one of the switch
ports, the frame is forwarded out only that port.
However, the switch’s CAM table, however, does have a finite size. Therefore, if the
CAM table ever fills to capacity, the switch is unable to learn new MAC addresses. As a
result, when frames arrive destined for these unlearned MAC addresses, the switch floods
a copy of these frames out all other switch interfaces, other than the interfaces they were
received on.