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Layer 3 Switching - Routing Fundamentals | Network Design | Repovive

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Network Design26 sections · 911 units44h total

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Layer 3 Switching

Routing in hardware

A Layer $3$ switch combines switching and routing in a single device. It routes between VLANs using hardware (ASICs) rather than software, achieving much higher performance.

Layer $3$ switches use Switched Virtual Interfaces (SVIs) to route between VLANs:

Switch(config)# ip routing
Switch(config)# interface vlan 10
Switch(config-if)# ip address 192.168.10.1 255.255.255.0

Switch(config)# interface vlan 20
Switch(config-if)# ip address 192.168.20.1 255.255.255.0

Traffic between VLANs stays within the switch. No external router needed. Throughput is limited only by the switch's backplane, often tens of gigabits per second.