Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureMedium
A network engineer is configuring a new Layer 3 switch to support inter-VLAN routing. The engineer wants to ensure that the switch utilizes hardware-based forwarding for maximum performance and efficiency. Which Cisco technology must be enabled and properly configured for this hardware-based forwarding to occur?
- ACisco Express Forwarding (CEF)
- BHot Standby Router Protocol (HSRP)
- CSpanning Tree Protocol (STP)
- DLink Aggregation Control Protocol (LACP)
Show answer & explanationAnswer & explanation
Correct answer: A. Cisco Express Forwarding (CEF)
Cisco Express Forwarding (CEF) is an advanced, hardware-based Layer 3 IP switching technology that optimizes network performance and scalability for larger networks. It pre-computes the entire forwarding table (FIB) and adjacency table, enabling faster packet forwarding compared to process switching.
Why the other options are wrong
- B. HSRP provides first-hop redundancy for default gateways, not hardware-based forwarding.
- C. STP is a Layer 2 protocol to prevent loops, not for hardware-based Layer 3 forwarding.
- D. LACP is a Layer 2 protocol for bundling physical links into a logical port-channel, not for hardware-based Layer 3 forwarding.
Cisco Express Forwarding (CEF)
A proprietary Cisco technology that optimizes Layer 3 packet forwarding by pre-computing routing and adjacency information into specialized data structures (FIB and adjacency table), enabling hardware-based forwarding.
- Enables hardware-based Layer 3 switching for high performance.
- Uses Forwarding Information Base (FIB) and Adjacency Table.
- Default forwarding mechanism on most modern Cisco routers/switches.
Memory trick: CEF: Cisco's Express Forwarding is Fast