STEP 26 — Configure Router-on-a-Stick (HO-R1)

Goal

• Make the router VLAN-aware
• Give each VLAN its own gateway IP
• Restore connectivity between VLANs

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🔹 What we will configure

Device: HO-R1
Physical interface: GigabitEthernet0/0 (the trunk to DIST-SW1)

VLAN	Subnet	Gateway
10 (USERS)	10.10.10.0/24	10.10.10.1
20 (SERVERS)	10.10.20.0/24	10.10.20.1
30 (WIFI)	10.10.30.0/24	10.10.30.1

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🔹 STEP 26.1 — Prepare the physical interface

(We do NOT put an IP on the physical interface.)

enable
configure terminal
interface gigabitEthernet0/0
 no ip address
 no shutdown
exit

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🔹 STEP 26.2 — VLAN 10 subinterface (USERS)

interface gigabitEthernet0/0.10
 encapsulation dot1Q 10
 ip address 10.10.10.1 255.255.255.0
exit

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🔹 STEP 26.3 — VLAN 20 subinterface (SERVERS)

interface gigabitEthernet0/0.20
 encapsulation dot1Q 20
 ip address 10.10.20.1 255.255.255.0
exit

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🔹 STEP 26.4 — VLAN 30 subinterface (WIFI)

interface gigabitEthernet0/0.30
 encapsulation dot1Q 30
 ip address 10.10.30.1 255.255.255.0
exit
end
write memory

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🔹 STEP 26.5 — Verify (LOOK only)

show ip interface brief

You should see:

• Gi0/0.10 → up/up
• Gi0/0.20 → up/up
• Gi0/0.30 → up/up

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🔹 STEP 26.6 — Update end devices (important)

PC in VLAN 10

• IP: 10.10.10.10
• Mask: 255.255.255.0
• Gateway: 10.10.10.1

Server in VLAN 20

• IP: 10.10.20.10
• Mask: 255.255.255.0
• Gateway: 10.10.20.1

Wi-Fi device (VLAN 30)

• IP: 10.10.30.10
• Mask: 255.255.255.0
• Gateway: 10.10.30.1

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🔹 STEP 26.7 — Test (this is the moment)

From VLAN 10 PC:

ping 10.10.20.10
ping 10.10.30.10

You should get replies ✅

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🧠 What you just mastered

• 802.1Q tagging
• Subinterfaces
• One VLAN = one gateway
• Inter-VLAN routing via ROAS

This is core CCNA and the foundation for Layer-3 switching later.