Identify the main differences between Layer 2 switching and Layer 3 routing in enterprise networks, and give a scenario where each would be used.

Identify the main differences between Layer 2 switching and Layer 3 routing in enterprise networks, and give a scenario where each would be used.

• A. Layer 2 switches forward based on MAC addresses within a broadcast domain; Layer 3 routers forward based on IP addresses between subnets; use L2 for access-layer flat networks, L3 for inter-subnet routing and WAN connectivity.
• B. Layer 2 forwards based on IP addresses; Layer 3 forwards based on MAC addresses.
• C. Layer 2 devices perform routing; Layer 3 devices perform switching.
• D. Layer 2 is only for data centers; Layer 3 is only for campuses.

Answer: (A)

Layer 2 switching makes forwarding decisions based on MAC addresses and keeps traffic inside a single broadcast domain defined by a VLAN, while Layer 3 routing uses IP addresses to move packets between different subnets. In practice, you use Layer 2 at the access layer to provide end-user connectivity within the same VLAN; frames are switched by MAC learning and only leave the VLAN when crossing to another VLAN or going to a router. Layer 3 is used to connect separate subnets, handle inter-subnet routing, and provide WAN or Internet connectivity, with routers (or multilayer switches) using IP routing to determine the next hop. For a Layer 2 scenario: an office floor where all devices (workstations, printers, IP phones) reside in the same VLAN and are connected to access switches. The switches learn MAC addresses and forward frames within that VLAN without routing. For a Layer 3 scenario: a campus network where separate subnets exist for Finance, HR, and Guest networks, and traffic between these subnets (and to external Internet services) is routed by a router or a multilayer switch that forwards packets based on IP addresses.

Layer 2 switching makes forwarding decisions based on MAC addresses and keeps traffic inside a single broadcast domain defined by a VLAN, while Layer 3 routing uses IP addresses to move packets between different subnets. In practice, you use Layer 2 at the access layer to provide end-user connectivity within the same VLAN; frames are switched by MAC learning and only leave the VLAN when crossing to another VLAN or going to a router. Layer 3 is used to connect separate subnets, handle inter-subnet routing, and provide WAN or Internet connectivity, with routers (or multilayer switches) using IP routing to determine the next hop.

For a Layer 2 scenario: an office floor where all devices (workstations, printers, IP phones) reside in the same VLAN and are connected to access switches. The switches learn MAC addresses and forward frames within that VLAN without routing.

For a Layer 3 scenario: a campus network where separate subnets exist for Finance, HR, and Guest networks, and traffic between these subnets (and to external Internet services) is routed by a router or a multilayer switch that forwards packets based on IP addresses.