Lab: getting started with Cisco Packet Tracer and a first topology

Aim and what you need

The aim of this lab is to get Packet Tracer running and build a working local area network (LAN) that you can reuse as the starting point for later labs. By the end you will be able to place devices, cable them, give them addresses and test reachability.

• A Windows, macOS or Linux computer with about 1 GB of free disk space.
• A free Cisco Networking Academy account. Packet Tracer is downloaded after you sign in and enrol on one of the free introductory courses that include it.
• About 45 minutes.

Tip: Packet Tracer only simulates Cisco IOS. Most commands match real kit, but some advanced features are missing. That is fine for CCNA-level practice.

Topology and addressing

Steps

1. Install Packet Tracer, open it and sign in with your Networking Academy account.
2. From the device library at the bottom, drag a 2960 switch, a 1941 router and three PCs onto the workspace.
3. Choose the copper straight-through cable. Connect each PC's FastEthernet0 to switch ports Fa0/1, Fa0/2 and Fa0/3, and router G0/0 to switch G0/1.
4. Click each PC, open Desktop then IP Configuration, and enter the address, mask 255.255.255.0 and gateway from the table.
5. Click R1, open the CLI tab, answer no to the setup dialogue, and enter the commands below.
6. Save the file as lab01-first-lan.pkt.

enable
configure terminal
hostname R1
interface g0/0
 ip address 192.168.10.1 255.255.255.0
 no shutdown
end
copy running-config startup-config

Verify

Open Desktop then Command Prompt on PC0 and run the commands below. Success means every ping gets replies (the first one may lose a packet while ARP resolves), and the router shows G0/0 as up/up.

ipconfig
ping 192.168.10.11
ping 192.168.10.1

show ip interface brief
show arp

Now switch to Simulation mode (bottom right), set the filter to ICMP and ARP, and ping again. Step through the events and watch the ARP broadcast flood every switch port, then the unicast ping travel only to the right PC. Seeing this is the best way to understand how a switch learns MAC addresses. Back in the switch CLI, show mac address-table lists what it learned.

Troubleshooting and clean-up

• Red link lights: the router interface is still shut down, or you used the wrong cable type. Amber lights on a new switch port usually turn green after spanning tree finishes, about 30 seconds.
• Ping to the router fails but PCs reach each other: check the router address and that no shutdown was entered.
• Request timed out everywhere: check the subnet mask on each PC. A typo such as 255.255.0.0 on one device breaks things in confusing ways. Try the subnet calculator.
• Use the realtime/simulation toggle to slow things down and spot where a packet stops.

Clean-up is simple: save the working file as a template, then use File, Save As for each new lab so you always keep a known-good copy. In exams and at work, this habit of documenting an addressing table before cabling saves a lot of time.