Cisco Packet Tracer: Small Enterprise Network

This activity puts into practice the concepts from the Networking Fundamentals (LAN/WAN) and Network Configuration and Troubleshooting lectures. You will build a small enterprise network step by step in Cisco Packet Tracer, configuring VLANs, inter-VLAN routing via a multilayer switch, DHCP, and wireless access. By the end, you will have connected all device types on a segmented network and seen how each layer of the design addresses a specific networking concern.

What You Will Need

Cisco Packet Tracer installed (download from netacad.com after creating a free account)
About 60-90 minutes

The Interface

Cisco Packet Tracer main interface

Adding Devices

In the bottom-left corner, the first row shows device categories. Clicking a category updates the second row with specific models. Use the search field between the rows to find a device by name.

Device category row

Once you select a category, the device list updates on the right:

Router selection list

Click a device, then click the canvas to place it, or drag and drop. For cables, click the cable type, then click the first device and choose a port. Selecting Automatically Choose Connection Type handles cable type and port for you.

Canvas and Simulation Modes

The canvas has a logical view (where you will spend most of your time) and a physical view (a rack/map view). There are two simulation modes:

Realtime: Devices power on and behave like real hardware. Links start orange while devices negotiate; click the fast-forward button to advance time. A red link means a misconfiguration.
Simulation: Step through network events one at a time. Filter the event list to the protocols you care about (ARP and ICMP are a good starting point for this activity).

Interacting with Devices

Click any device to open its panel. The tabs you will use most:

Physical: Power the device on or off; add or swap hardware modules (the device must be off to change modules).
Config: Configure global settings and interfaces using a graphical form.
Desktop (PCs and end-user devices): Run Command Prompt, Web Browser, and IP Configuration.
CLI (switches, routers, multilayer switches): Full IOS command-line interface.

Part 1: VLAN Setup

Lecture concept: VLANs and network segmentation (Network Configuration and Troubleshooting). VLANs partition a single physical switch into multiple isolated broadcast domains. Here you will create two VLANs representing two departments and assign switch ports to them.

Add five PCs to the canvas: PC0, PC1, PC2, PC3, PC4.
Add two access switches (model 2960): access-SW0 and access-SW1. Connect PC0, PC1, and PC2 to access-SW0 via straight-through cables (FastEthernet ports, starting from Fa0/1). Connect PC3 and PC4 to access-SW1 the same way.
Add a distribution switch (model 2960): dist-SW. Connect it to each access switch using crossover cables on the GigabitEthernet ports of the access switches and FastEthernet ports on the distribution switch.

Lecture connection: The lecture’s Core Network Devices section explains that straight-through cables connect unlike device types (PC to switch) while crossover cables connect like device types (switch to switch). Modern switches with Auto-MDIX detect the cable type automatically, but Packet Tracer models older hardware that does not.
Assign IP addresses to the PCs. Use two subnets for the two departments:
- 192.168.10.0/24 for SALES
- 192.168.20.0/24 for FINANCE
On each PC: click the PC, go to Desktop > IP Configuration, and enter the IPv4 address and subnet mask (255.255.255.0).

Rename each PC to include its IP address (for example, SALES-10.100) so you can see subnet membership at a glance on the canvas without opening each device.
Open a Command Prompt on PC0 and try pinging PC1 (same subnet) and PC4 (different subnet). Note the results before continuing.
Configure VLANs on all three switches. On each switch, open the CLI tab and run:
```
en
conf t
vlan 10
 name SALES
vlan 20
 name FINANCE
exit
exit
show vlan
```
Assign each access port to the correct VLAN. On each access switch, open the Config tab, select the interface connected to each PC, and set the VLAN. You can also do this from the CLI:
```
interface FastEthernet0/1
 switchport access vlan 10
```
Set the uplink ports connecting the access switches to the distribution switch to trunk mode in the Config tab. The remote end updates automatically.

Part 2: Inter-VLAN Routing

Lecture concept: Routing Basics (Networking Fundamentals) and VLANs and network segmentation (Network Configuration and Troubleshooting). Layer 2 switches forward frames within a VLAN but cannot route between them. A multilayer switch (MLS) adds Layer 3 routing and uses Switch Virtual Interfaces (SVIs) to provide a default gateway per VLAN.

Add two more VLANs to all three switches:
- 192.168.99.0/24 for MANAGEMENT
- 192.168.200.0/24 for WIFI
Add a multilayer switch (model 3560, the MLS) to the canvas. Connect it to dist-SW using the correct cable, set both ports to trunk mode, and add all four VLANs to the MLS.
Configure a Switch Virtual Interface (SVI) for each VLAN on the MLS. In the CLI:
```
interface vlan 10
 ip address 192.168.10.1 255.255.255.0
```
Repeat for VLANs 20, 99, and 200 with the correct subnet. Then enable IP routing:
```
ip routing
```
Verify with show run.
Set the default gateway on each PC to 192.168.x.1 (the SVI for its VLAN). Open each PC, go to Desktop > IP Configuration, and fill in the Default Gateway field.

Now repeat the ping test from Part 1, Step 5. PC0 should now be able to reach PC4.

Lecture connection: The lecture’s Routing Basics section explains that a default gateway is the IP address a host sends packets to when the destination is outside its own subnet. The SVI acts as the default gateway for every host in that VLAN.

Part 3: Static Routing to a Border Router

Lecture concept: Routing Basics (Networking Fundamentals). Static routes are manually configured paths used when there is a small number of routes or when you need predictable, controlled forwarding behavior. Here you will connect the MLS to an upstream router and configure static routes on both devices.

Add a router (model 4331) to the canvas. Connect it to the MLS with the appropriate cable.
On the router, open the Config tab, power on the connected interface, then set:
- IPv4 Address: 172.16.1.1
- Subnet Mask: 255.255.255.252
Lecture connection: The IP Addressing and Subnetting section covers the /30 (255.255.255.252) subnet, which provides exactly two usable host addresses. This is the standard choice for point-to-point links between routers, where only the two endpoints need addresses.
On the MLS, disable switching on the port connected to the router (converting it from a Layer 2 switch port to a Layer 3 routed port):
```
interface GigabitEthernet0/2
 no switchport
 ip address 172.16.1.2 255.255.255.252
```

Add static routes on both devices:

ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/2   (on the MLS)
ip route 192.168.0.0 255.255.0.0 GigabitEthernet0/0/0   (on the router)

Part 4: DHCP

Lecture concept: Core Network Services: DNS, DHCP, and NAT (Networking Fundamentals) and DHCP: dynamic addressing (Network Configuration and Troubleshooting). DHCP eliminates manual IP assignment by having clients request an address from a server. When the DHCP server is on a different subnet, a relay agent (ip helper-address) forwards the broadcast to the server’s unicast address.

Add a server to the canvas. Connect it to the MLS and set the port to Access VLAN 99 (Management).
On the server, configure a static IP:
- IPv4 Address: 192.168.99.100
- Subnet Mask: 255.255.255.0
- Default Gateway: 192.168.99.1
- DNS Server: 8.8.8.8
In the server’s Services > DHCP tab, turn the service On. Add a pool for VLAN 10:
- Pool Name: VLAN10-Pool
- Default Gateway: 192.168.10.1
- DNS Server: 8.8.8.8
- Start IP Address: 192.168.10.200
- Subnet Mask: 255.255.255.0
- Maximum Users: 50
Click Add. Repeat for VLAN 20 with the corresponding values.
Add a DHCP relay helper on the MLS so VLAN clients can reach the server across subnet boundaries:
```
interface vlan 10
 ip helper-address 192.168.99.100
```
Repeat for VLAN 20.
Add two new PCs. For each one:
- Connect it to an access switch and set the port VLAN.
- Open the PC, go to Config, and set the IPv4 source to DHCP.
Fast-forward and verify the PCs receive addresses in the expected range.

Lecture connection: The DHCP: dynamic addressing section’s lease process describes the four-step DORA sequence (Discover, Offer, Request, Acknowledge). Switch to simulation mode and add a new DHCP client to watch this exchange step by step.

Part 5: Wireless

Lecture concept: Wi-Fi fundamentals (Network Configuration and Troubleshooting). Enterprise wireless uses a Wireless LAN Controller (WLC) to manage multiple lightweight access points (LAPs) centrally, rather than configuring each access point independently.

Add a Wireless LAN Controller (WLC 3504) to the canvas. Connect it to the MLS and set the port to Access VLAN 99.
Configure the WLC’s management IP:
- IPv4 Address: 192.168.99.101
- Subnet Mask: 255.255.255.0
- Default Gateway: 192.168.99.1
- DNS Server: 8.8.8.8
Fast-forward, then from any wired PC open the Web Browser and navigate to http://192.168.99.101.

The WLC web interface is very slow in Packet Tracer. Allow 30-60 seconds for the page to load.
Create an admin account. In the setup wizard, confirm the management IP settings and proceed to Create Your Wireless Networks. Choose a network name (SSID) and WPA2 passphrase. Click through and apply. The WLC reboots.
While the WLC reboots, add a DHCP pool on the server for VLAN 200 (Wifi), starting at 192.168.200.100, with the WLC address (192.168.99.101) entered in the WLC Address field. Add a DHCP relay on the MLS for VLAN 200.
Add two lightweight access points (LAP-PT) to the canvas. Connect them to any switch and set the ports to VLAN 200. In each LAP’s Physical tab, drag the power cord to the power socket.

Set each LAP to DHCP in the Config tab. Fast-forward until they receive IP addresses.
Log back in to the WLC at https://192.168.99.101 (note the S). Go to WLANs > AP Groups, create a group called LAP, add the SSID under WLANs, and add both access points under APs.
Add one or two wireless devices (tablets, smartphones, or laptops). In the device’s Config tab, enter the SSID, enable WPA2-PSK, and enter the passphrase. Fast-forward and verify the device connects to one of the LAPs.

Verify Your Understanding

Here is how each part of this activity maps to the lectures:

What you did	Lecture section
Assigned PCs to subnets and observed broadcast isolation	IP Addressing and Subnetting; VLANs and network segmentation
Created VLANs and assigned ports	VLANs and network segmentation
Added trunk ports between switches	VLANs and network segmentation
Configured SVIs and enabled IP routing on the MLS	Routing Basics
Set default gateways on endpoints	Routing Basics
Added a /30 point-to-point link to a border router	IP Addressing and Subnetting; Static IP routing
Deployed a DHCP server and relay agents	Core Network Services: DHCP; DHCP: dynamic addressing
Connected wireless devices through a WLC and LAPs	Wi-Fi fundamentals; Enterprise wireless security

Consider the following questions:

Broadcast domains: Before configuring VLANs, all five PCs were on the same switch. What would happen if PC0 sent an ARP broadcast? After VLANs, what changed?
Trunk ports: Why do the uplinks between switches carry all VLANs instead of just one? What would break if you set those ports to access mode for VLAN 10?
MLS vs. external router: You used a multilayer switch for inter-VLAN routing instead of connecting each VLAN to a separate router interface. What are the trade-offs between these two designs?
DHCP relay: The DHCP server is on VLAN 99 but serves clients on VLANs 10 and 20. Why does a relay agent work here when a simple broadcast would not reach across subnets?
WLC vs. standalone APs: In the enterprise wireless setup, the WLC manages both LAPs centrally. What operational advantages does this provide over configuring each access point independently?
Static vs. dynamic routing: You configured static routes between the MLS and the border router. Under what circumstances would you prefer a dynamic routing protocol (like OSPF or BGP) instead?