Lab 3: Implement Inter-VLAN Routing

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Lesson format9 sections1 code block1 practice itemUpdated Oct 2, 2026

bash

R1# configure terminal
R1(config)# interface gi0/0
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface gi0/0.10
R1(config-subif)# encapsulation dot1q 10
R1(config-subif)# ip address 10.10.10.1 255.255.255.0
R1(config-subif)# exit
R1(config)# interface gi0/0.20
R1(config-subif)# encapsulation dot1q 20
R1(config-subif)# ip address 10.10.20.1 255.255.255.0
R1(config-subif)# exit

Lab 3 introduces Layer 3 routing between VLANs. Take Lab 2's topology, add a router connected via trunk, and configure router-on-a-stick subinterfaces. Hosts in VLAN 10 and VLAN 20 should now be able to reach each other through the router.

#The Lab Topology#link

#Configuration Steps#link

Configure R1's physical Gi0/0 with `no shutdown`
Configure subinterface Gi0/0.10 with dot1q encapsulation VLAN 10 and IP 10.10.10.1/24
Configure subinterface Gi0/0.20 with dot1q encapsulation VLAN 20 and IP 10.10.20.1/24
Configure SW1's port to R1 as a trunk with allowed VLANs 10,20 and native VLAN 99
Configure PC-A's default gateway as 10.10.10.1
Configure PC-B's default gateway as 10.10.20.1
Verify: PC-A pings PC-B (inter-VLAN) and pings its gateway

Complete the configuration above. From PC-A: ping 10.10.20.10 (PC-B) — should succeed. Ping 10.10.20.1 (R1's VLAN 20 subinterface) — should succeed. Verify with `show ip interface brief` on R1 that both subinterfaces are up/up.

★ 20 XPmedium

quiz BLOCK (★ 20 XP)

PC-A pings PC-B and receives 'Destination host unreachable' from 10.10.10.1 (its gateway). What's the most likely issue?

Select your proof vectors above

callout

Lab 3 adds routing. Verify by testing PC-A to PC-B and by inspecting subinterface state. Next lab adds STP and EtherChannel for redundancy.

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The Lab Topology Configuration Steps

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October 2, 2026

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{
  "mcpServers": {
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Laboratory sanity code

Isolate active probes on matched virtual networks and keep execution streams sandboxed.

R1# configure terminal

R1(config)# interface gi0/0

R1(config-if)# no shutdown

R1(config-if)# exit

R1(config)# interface gi0/0.10

R1(config-subif)# encapsulation dot1q 10

R1(config-subif)# ip address 10.10.10.1 255.255.255.0

R1(config-subif)# exit

R1(config)# interface gi0/0.20

R1(config-subif)# encapsulation dot1q 20

R1(config-subif)# ip address 10.10.20.1 255.255.255.0

R1(config-subif)# exit