Networking

Router-on-a-Stick vs Layer 3 Switch

Network Design diagram · made in Skemio

Diagram comparing a WAN router connected to a Layer 3 switch routing across multiple access switches and VLAN client nodes at wire speed.
Diagram comparing a WAN router connected to a Layer 3 switch routing across multiple access switches and VLAN client nodes at wire speed.
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What it shows

  • Router-on-a-stick hairpins all inter-VLAN traffic across a single trunk link.
  • Layer 3 switches route packets directly in ASIC hardware at wire speed.
  • Use router subinterfaces for sub-gigabit branches; use L3 for campus cores.

The takeaway

Offload inter-VLAN traffic to hardware-switched Layer 3 ASICs to prevent router trunk bottlenecks.

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