Switch vs Router: Layer 2 Switching vs Layer 3 Routing

Sat, 01 Aug 2026 20:05:00 +0900

Overview

A switch connects devices within a single network by forwarding traffic based on MAC addresses, while a router connects separate networks together by forwarding traffic based on IP addresses. Plugging a device into the wrong one is a common source of confusion — one expands a LAN, the other bridges LANs to each other or to the internet.

Comparison Diagram

Comparison Table

Aspect	Switch	Router
OSI layer	Layer 2 (Data Link)	Layer 3 (Network)
Addressing used	MAC addresses	IP addresses
Forwarding table	MAC address table (CAM table), learned automatically	Routing table, built via static routes or routing protocols
Broadcast domain	Devices share one broadcast domain (unless VLANs are configured)	Separates traffic into distinct broadcast domains per interface
Typical placement	Connects devices within a single LAN segment	Connects different networks together, e.g. LAN to LAN or LAN to WAN
Unknown-destination handling	Floods frame to all ports in the VLAN when MAC is unknown	Drops or rejects packets with no matching route
Built-in services	Basic switching only, plus optional VLANs/QoS on managed models	Often includes NAT, DHCP, firewall, and VPN functions
Typical device	Cisco Catalyst switch in a wiring closet	Home router or edge router linking a LAN to an ISP

Key Differences

Switches forward traffic using MAC addresses at Layer 2, while routers forward using IP addresses at Layer 3.
A switch keeps connected devices in one broadcast domain; a router splits traffic into separate domains.
Switches flood frames to unknown destinations within a VLAN; routers simply drop packets they can’t route.
Routers commonly bundle NAT and firewall features that switches don’t provide.
Switches scale port count for a single network; routers scale the number of distinct networks a device can reach.

When to Use Each

Switch

Router on IT Comparison

Switch vs Router: Layer 2 Switching vs Layer 3 Routing

Overview

Comparison Diagram

Comparison Table

Key Differences

When to Use Each