Why does Cisco force you to learn this topology? Because Lab 162 mirrors the Campus LAN Design:
If you work at any medium-to-large enterprise, the switch in your wiring closet is configured exactly like SW1 in this lab.
Now comes the moment of truth. Let’s verify that our configuration works.
1. Verify Router Interfaces: Check if the sub-interfaces are "up/up" and have the correct IPs.
R1# show ip interface brief
You should see g0/0.10 and g0/0.20 with status "up".
2. Verify Trunking on Switch: Ensure the link to the router is indeed trunking.
S1# show interfaces trunk
You should see VLANs 10 and 20 allowed on the trunk.
3. The Ping Test: From PC1, attempt to ping PC2. cisco+lab+162
C:\> ping 192.168.20.10
If the ping is successful (replies received), congratulations! You have successfully configured Inter-VLAN routing. The first ping might time out due to ARP processes, but subsequent pings should succeed.
Without trunks, SW1’s VLAN 10 traffic cannot reach SW2’s VLAN 10. Trunks using IEEE 802.1Q add a VLAN tag to each frame.
On SW1 (uplink to Multilayer SW):
interface gigabitEthernet 0/1
switchport trunk encapsulation dot1q (Required on older switches)
switchport mode trunk
switchport trunk allowed vlan 10,20
no shutdown
On SW2 (uplink to Multilayer SW):
interface gigabitEthernet 0/1
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed vlan 10,20
no shutdown
Verification: Run show interfaces trunk. You should see the ports listed with Native VLAN "1" and allowed VLANs "10,20". If this output is blank, the trunk did not form—check for mismatched encapsulation or cabling.
Before testing, verify the routing table on the Multilayer Switch:
show ip route
You should see two directly connected routes: Why does Cisco force you to learn this topology
Now, from PC1, attempt to ping PC4:
ping 192.168.20.3
Expected result: Success (!!!) or (!.). If it fails, proceed to the troubleshooting section.
In Part 1, you will connect to the router via the console and issue basic show commands to view the router's status.
Step 1: Connect to the router. a. Connect the PC to the router using a console cable. b. Open a terminal emulator program (such as PuTTY or TeraTerm). c. Press Enter to get the router prompt.
Step 2: Enter Privileged EXEC mode.
a. At the user EXEC prompt (Router>), enter the enable command.
Router> enable
Router#
b. Notice the prompt changes from > to #, indicating you are in Privileged EXEC mode.
Step 3: Use the show version command.
a. Enter the show version command to view system hardware and software status. If you work at any medium-to-large enterprise, the
Router# show version
b. Question: What is the IOS version? (Answer varies based on the lab image, e.g., "Version 15.1(4)M") c. Question: What is the amount of total memory (RAM)? (Look for "xxxxxK/xxxxxK bytes of memory". The first number is Main Memory, the second is I/O Memory). d. Question: What is the Configuration Register setting? (Typically 0x2102).
Step 4: Use the show running-config command.
a. Enter the command to view the currently running configuration.
Router# show running-config
b. Question: What is the hostname of the router? (Default is usually "Router"). c. Question: How many interfaces does the router have? (Look for lines starting with "interface". It usually lists GigabitEthernet or FastEthernet and Serial interfaces).
Step 5: Use the show ip interface brief command.
This command is used to get a quick summary of the interface status.
a. Enter the command:
Router# show ip interface brief
b. Observe the output columns: Interface, IP-Address, OK?, Method, Status, Protocol. c. Question: What is the status of the interfaces? (If no cables are connected, Status is usually "administratively down" or "down").
Step 6: Use the show interfaces command.
a. Enter the command for a specific interface (e.g., G0/0 or Fa0/0).
Router# show interfaces gigabitethernet 0/0
b. Look for the line indicating the bandwidth (BW) and the MAC address (Hardware address).