Which table is used to make the decision on whether a frame should even be forwarded based on the frame being permitted in an ACL?
- CAM
- MAC address table
- IP Routing table
- TCAM
Explanation: The TCAM (Ternary Content-Addressable Memory) is the specific hardware table used to store Access Control Lists (ACLs), Quality of Service (QoS), and other information generally associated with upper-layer processing.
When a switch receives a frame and must decide, "Should it even forward the frame?", it relies on the TCAM to identify the frame according to the configured ACLs. A single lookup in the TCAM is all that is required to determine whether a frame is permitted or denied.
Cisco switches are designed to perform CAM (Layer 2 forwarding) and TCAM (ACL/QoS) lookups in parallel. This hardware-based approach ensures that the switch can enforce security policies and filtering tasks at wire speed without any performance degradation. In contrast, the CAM table (or MAC address table) is primarily used for making Layer 2 forwarding decisions based on destination MAC addresses, not for enforcing ACL permit/deny logic.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
