What are the differences between Layer 2 and Layer 3 switches?

Layer 2 switches operate at the Data Link layer, while Layer 3 switches add routing capabilities at the Network layer.

Layer 2 Switch

• Forwards frames based on MAC addresses
• Maintains MAC address table (CAM)
• Supports VLAN, STP, LACP
• Cannot route between VLANs (needs external router)
• Lower cost, higher port count

Layer 3 Switch

• Includes all Layer 2 features
• Routes packets between subnets/VLANs
• Supports static routing, RIP, OSPF, sometimes BGP
• Hardware-accelerated routing (ASIC-based)
• Higher cost, but reduces need for separate routers

When to Use Layer 3 Switches

• Inter-VLAN routing in medium to large networks
• Core/aggregation layer requiring high-speed routing
• Multi-site substation networks with distributed subnets
• Anywhere ACLs and routing policies are needed

Layer 3 Features to Look For

• VRRP: Gateway redundancy
• OSPF/RIP: Dynamic routing protocols
• Multicast routing: PIM-SM/DM for video
• IPv6 support: Future-proof deployments
• ACL: Layer 3/4 access control lists

Cost-Benefit

A Layer 3 switch may cost 2-3x more than Layer 2 but eliminates the need for a separate router in many designs, often reducing total cost and latency.