4.2.7 Packet Tracer – Configure Router-on-a-Stick Inter-VLAN Routing – Instructions Answer

Packet Tracer – Configure Router-on-a-Stick Inter-VLAN Routing (Instructor Version)

Addressing Table

DeviceInterfaceIPv4 AddressSubnet MaskDefault Gateway


  • Part 1: Add VLANs to a Switch
  • Part 2: Configure Subinterfaces
  • Part 3: Test Connectivity with Inter-VLAN Routing


In this activity, you will configure VLANs and inter-VLAN routing. You will then enable trunk interfaces and verify connectivity between VLANs.


Part 1: Add VLANs to a Switch

Step 1: Create VLANs on S1.

Create VLAN 10 and VLAN 30 on S1.

Step 2: Assign VLANs to ports.

a. Configure interfaces F0/6 and F0/11 as access ports and assign VLANs.

  • Assign the port connected to PC1 to VLAN 10.
  • Assign the port connected to PC3 to VLAN 30.

b. Issue the show vlan brief command to verify VLAN configuration.

S1# show vlan brief
VLAN  Name                             Status    Ports
----  -------------------------------- --------- -------------------------------
1     default                          active    Fa0/1, Fa0/2, Fa0/3, Fa0/4
                                                 Fa0/5, Fa0/7, Fa0/8, Fa0/9
                                                 Fa0/10, Fa0/12, Fa0/13, Fa0/14
                                                 Fa0/15, Fa0/16, Fa0/17, Fa0/18
                                                 Fa0/19, Fa0/20, Fa0/21, Fa0/22
                                                 Fa0/23, Fa0/24, Gig0/1, Gig0/2
10    VLAN0010                         active    Fa0/11
30    VLAN0030                         active    Fa0/6
1002  fddi-default                     active
1003  token-ring-default               active
1004  fddinet-default                  active
1005  trnet-default                    active

Step 3: Test connectivity between PC1 and PC3.

From PC1, ping PC3.

Were the pings successful? Why did you get this result?

Part 2: Configure Subinterfaces

Step 1: Configure subinterfaces on R1 using the 802.1Q encapsulation.

a. Create the subinterface G0/0.10.

  • Set the encapsulation type to 802.1Q and assign VLAN 10 to the subinterface.
  • Refer to the Address Table and assign the correct IP address to the subinterface.
R1(config)# int g0/0.10
R1(config-subif)# encapsulation dot1Q 10
R1(config-subif)# ip address

b. Repeat for the G0/0.30 subinterface.

Step 2: Verify Configuration.

a. Use the show ip interface brief command to verify subinterface configuration. Both subinterfaces are down. Subinterfaces are virtual interfaces that are associated with a physical interface. Therefore, in order to enable subinterfaces, you must enable the physical interface that they are associated with.

b. Enable the G0/0 interface. Verify that the subinterfaces are now active.

Part 3: Test Connectivity with Inter-VLAN Routing

Step 1: Ping between PC1 and PC3.

From PC1, ping PC3. The pings should still fail. Explain.

Step 2: Enable trunking.

a. On S1, issue the show vlan command.

What VLAN is G0/1 assigned to?

b. Because the router was configured with multiple subinterfaces assigned to different VLANs, the switch port connecting to the router must be configured as a trunk. Enable trunking on interface G0/1.

How can you determine that the interface is a trunk port using the show vlan command?

c. Issue the show interface trunk command to verify that the interface is configured as a trunk.

Step 3: Test Connectivity

If the configurations are correct, PC1 and PC3 should be able to ping their default gateways and each other.

What addresses do PC1 and PC3 use as their default gateway addresses?

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