At which OSI layer does a multilayer switch primarily operate to enable routing?

At which OSI layer does a multilayer switch primarily operate to enable routing?

• A. Layer 2
• B. Layer 4
• C. Layer 1
• D. Layer 3

Answer: (D)

Routing decisions are made at the Network layer. A multilayer switch combines fast Layer 2 switching with Layer 3 routing capabilities, so it can move packets between different networks or VLANs by examining IP addresses. That Layer 3 functionality—inter-VLAN routing and routing between networks—is what enables the device to perform routing. Layer 2 handles switching within a single network using MAC addresses, Layer 1 is just the physical medium, and Layer 4 involves transport ports but isn’t where routing decisions are defined.

Routing decisions are made at the Network layer. A multilayer switch combines fast Layer 2 switching with Layer 3 routing capabilities, so it can move packets between different networks or VLANs by examining IP addresses. That Layer 3 functionality—inter-VLAN routing and routing between networks—is what enables the device to perform routing. Layer 2 handles switching within a single network using MAC addresses, Layer 1 is just the physical medium, and Layer 4 involves transport ports but isn’t where routing decisions are defined.