MAC Address Table

D.

Both the MAC address table and the Ternary Content Addressable Memory (TCAM) are used in network switches to make forwarding decisions, but they differ in their operation and purpose.

The MAC address table is a database that is used by a switch to map MAC addresses to the corresponding switch port. When a frame arrives at a switch, the switch looks up the destination MAC address in the MAC address table to determine the outgoing switch port. If the MAC address is not found in the table, the switch will flood the frame to all ports except the incoming port. The MAC address table is updated dynamically as frames are forwarded through the switch, and entries are aged out of the table after a configurable period of time.

On the other hand, TCAM is a specialized type of memory that is used to perform fast and efficient lookups of patterns in data. TCAM is typically used in switches to implement Access Control Lists (ACLs) and Quality of Service (QoS) policies. When a frame arrives at a switch, the switch can use TCAM to quickly determine if the frame matches any ACL rules or QoS policies. If a match is found, the switch can take the appropriate action, such as dropping the frame, forwarding it to a specific port, or setting a specific QoS priority.

To answer the question, option B is incorrect because router prefix lookups happen in the router's Routing Information Base (RIB) rather than TCAM. Option C is incorrect because TCAM can support partial matches using a mask, allowing for flexible matching of patterns. Option D is partly correct, as TCAM is often used to store ACL and QoS information, but the MAC address table is typically stored in a separate memory. Option A is the correct answer, as TCAM is used to make Layer 2 forwarding decisions based on criteria such as VLAN ID, MAC address, and IP address, while the MAC address table is used to map MAC addresses to switch ports.

In summary, the MAC address table and TCAM serve different purposes in a switch, with the former used for MAC address mapping and the latter used for fast pattern matching for ACL and QoS policies.