Lab 21: Inter-VLAN Routing on a Layer 3 Switch
Router-on-a-stick is the classic; SVIs on a Layer 3 switch are how real networks do it — VLAN gateways living on the switch itself, routing at hardware speed. Difficulty: Intermediate · Time: ~30 min.
Lab objectives
- Enable ip routing on a multilayer switch
- Create SVIs as VLAN gateways
- Assign access ports and test inter-VLAN pings
- Compare with router-on-a-stick
Topology & addressing
1× 3560/3650 multilayer switch, PCs: VLAN 10 (192.168.10.11, gw .1) and VLAN 20 (192.168.20.11, gw .1).
Step-by-step configuration
ip routing | Turn on Layer 3 forwarding — the step everyone forgets |
vlan 10 · vlan 20 + assign access ports | Layer 2 groundwork as usual |
interface vlan 10ip address 192.168.10.1 255.255.255.0no shutdown | SVI = VLAN 10's gateway (repeat for VLAN 20) |
Verification
show ip interface brief — both Vlan10 and Vlan20 up with IPs (an SVI needs an active port in its VLAN to come up). PC-to-PC across VLANs pings immediately. Same outcome as Lab 4's router-on-a-stick — but no external router, no trunk bottleneck: this is the enterprise standard.
Next lab: labs hub · test yourself: CCNA practice test.
Frequently asked questions
Why is my SVI down?
An SVI stays down until at least one active port exists in that VLAN (or the VLAN itself doesn't exist) — check show vlan brief and port states.
What's the advantage over router-on-a-stick?
Hardware-speed routing inside the switch, no shared trunk choke point, fewer boxes — the standard in every modern LAN.
Do PCs need any special config?
No — just the SVI address as their gateway, exactly like any router gateway.
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