I built a simulated university campus network built to apply concepts I learnt from my CompTIA Network+ studies: VLANs, IPv4 subnetting, trunking, inter-VLAN routing, OSPF, and redundant network paths.
The campus connects 72 PCs and 12 printers across four schools blocks and 12 floors, 3 floors per school block. Each school has a Layer 3 switch for routing between floors and a dedicated router for communication with the other schools. The four routers form a full mesh using fiber and copper links.
Tools and technologies: Cisco Packet Tracer · Cisco IOS CLI · VLANs · IEEE 802.1Q · IPv4 · SVIs · OSPF area 0 · Fiber Ethernet
- Design a campus network with clearly defined switching and routing roles.
- Separate every floor into its own VLAN and subnet.
- Configure access ports for end devices and trunks between switches.
- Provide floor default gateways using switched virtual interfaces (SVIs).
- Configure routed links between building switches and routers.
- Establish fiber and copper connections between the four routers.
- Use OSPF to exchange routes throughout the campus.
- Test connectivity and demonstrate recovery after a link failure.
The campus consists of the School of Engineering, School of Business, School of Medicine, and School of Art. Each school has three floors, with six PCs and one printer on each floor of the building.
The project began with a collapsed-core idea. I added dedicated building routers to practice router configuration and routing between buildings. The final design uses building distribution switches and a routed campus backbone.
| Component | Role |
|---|---|
| Floor access switch | Connects six PCs and one printer to their floor VLAN |
| Building Layer 3 switch | Provides the three floor gateways and routes between floor subnets |
| Building router | Exchanges routes and forwards traffic between schools |
| Full-mesh router backbone | Provides direct connections and alternate paths between buildings |
Each building follows this structure:
Floor 1: 6 PCs + printer → Access switch ──┐
Floor 2: 6 PCs + printer → Access switch ──┼── Building Layer 3 switch
Floor 3: 6 PCs + printer → Access switch ──┘ │
Building router
│
Other school routers
Engineering ───────── Fiber ───────── Medicine
│ │
Fiber Fiber
│ │
Business ─────────── Fiber ─────────── Art
Additional diagonal links:
Engineering ↔ Art — Copper
Medicine ↔ Business — Copper
Every router connects to the other three routers, giving six inter-router links. No central transit switch is used.
- Within a floor: The access switch forwards traffic between devices in the same VLAN and subnet.
- Between floors in one building: The source PC sends traffic to its gateway SVI. The Layer 3 switch routes it to the destination floor.
- Between buildings: Traffic passes through the source building's Layer 3 switch and router, follows an OSPF-selected campus path, and reaches the destination building's router and Layer 3 switch.
| Connection | Source interface | Destination interface |
|---|---|---|
| Six PCs → floor access switch | PC Ethernet ports | Fa0/1–Fa0/6 |
| Printer → floor access switch | Printer Ethernet port | Fa0/7 |
| Floor 1 access switch → building switch | Gi0/1 | Fa0/1 |
| Floor 2 access switch → building switch | Gi0/1 | Fa0/2 |
| Floor 3 access switch → building switch | Gi0/1 | Fa0/3 |
| Building switch → building router | Gi0/1 | Gi0/0 |
Each 2911 uses two HWIC-1GE-SFP cards, each populated with a GLC-LH-SMD transceiver. The router is powered off before installing the hardware and powered on afterward. The optical links use single-mode fiber.
I used fiber to supports long distance communication between school blocks and avoid electromagnetic interference. Though fiber alone does not guarantee uninterrupted traffic, The redundant topology and routing protocol provide alternate paths when a connection fails.
| School | Organizational address allocation |
|---|---|
| Engineering | 10.1.0.0/16 |
| Business | 10.2.0.0/16 |
| Medicine | 10.3.0.0/16 |
| Art | 10.4.0.0/16 |
Every floor uses a /28 subnet with mask 255.255.255.240. This provides 16 total addresses and 14 usable host addresses. Six PCs, one printer, and one gateway use eight addresses, leaving six available for future expansion.
| School | Floor | VLAN | VLAN name | Subnet | Gateway SVI address |
|---|---|---|---|---|---|
| Engineering | 1 | 10 | ENG_F1 | 10.1.10.0/28 |
10.1.10.1 |
| Engineering | 2 | 20 | ENG_F2 | 10.1.20.0/28 |
10.1.20.1 |
| Engineering | 3 | 30 | ENG_F3 | 10.1.30.0/28 |
10.1.30.1 |
| Business | 1 | 40 | BUS_F1 | 10.2.40.0/28 |
10.2.40.1 |
| Business | 2 | 50 | BUS_F2 | 10.2.50.0/28 |
10.2.50.1 |
| Business | 3 | 60 | BUS_F3 | 10.2.60.0/28 |
10.2.60.1 |
| Medicine | 1 | 70 | MED_F1 | 10.3.70.0/28 |
10.3.70.1 |
| Medicine | 2 | 80 | MED_F2 | 10.3.80.0/28 |
10.3.80.1 |
| Medicine | 3 | 90 | MED_F3 | 10.3.90.0/28 |
10.3.90.1 |
| Art | 1 | 100 | ART_F1 | 10.4.100.0/28 |
10.4.100.1 |
| Art | 2 | 110 | ART_F2 | 10.4.110.0/28 |
10.4.110.1 |
| Art | 3 | 120 | ART_F3 | 10.4.120.0/28 |
10.4.120.1 |
| Last octet | Assignment |
|---|---|
.0 |
Network address |
.1 |
Floor gateway on the Layer 3 switch |
.2–.7 |
Six PCs |
.8 |
Printer |
.9–.14 |
Available |
.15 |
Broadcast address |
The Engineering Floor 1's first PC uses 10.1.10.2, mask 255.255.255.240, and gateway 10.1.10.1. Its printer uses 10.1.10.8 with the same mask and gateway.
This is the complete addressing inventory for every individual assignment.
Each connection has its own /30 subnet with mask 255.255.255.252 and two usable addresses. So they could be two addresses shared between the switch and the router.
| School | Subnet | Switch Gi0/1 | Router Gi0/0 | Broadcast |
|---|---|---|---|---|
| Engineering | 192.168.1.0/30 |
192.168.1.1 |
192.168.1.2 |
192.168.1.3 |
| Business | 192.168.2.0/30 |
192.168.2.1 |
192.168.2.2 |
192.168.2.3 |
| Medicine | 192.168.3.0/30 |
192.168.3.1 |
192.168.3.2 |
192.168.3.3 |
| Art | 192.168.4.0/30 |
192.168.4.1 |
192.168.4.2 |
192.168.4.3 |
All six connections also use mask 255.255.255.252.
| Connection | Cable | Subnet | Source | Distination |
|---|---|---|---|---|
| Engineering–Medicine | Fiber | 192.168.100.0/30 |
Engineering: 192.168.100.1 |
Medicine: 192.168.100.2 |
| Engineering–Business | Fiber | 192.168.100.4/30 |
Engineering: 192.168.100.5 |
Business: 192.168.100.6 |
| Business–Art | Fiber | 192.168.100.8/30 |
Business: 192.168.100.9 |
Art: 192.168.100.10 |
| Medicine–Art | Fiber | 192.168.100.12/30 |
Medicine: 192.168.100.13 |
Art: 192.168.100.14 |
| Engineering–Art | Copper | 192.168.100.16/30 |
Engineering: 192.168.100.17 |
Art: 192.168.100.18 |
| Medicine–Business | Copper | 192.168.100.20/30 |
Medicine: 192.168.100.21 |
Business: 192.168.100.22 |
The four school transit networks and six router transit networks do not overlap with the floor networks.
Each floor VLAN exists on its access switch and its building's Layer 3 switch. Physical ports connected to PCs and printers are assigned to that VLAN.
switchport mode access makes the ports access ports. switchport access vlan 80 places their connected devices in VLAN 10. The uplink is configured separately.
A trunk carries VLAN-tagged traffic between switches. Each floor uplink is configured as a trunk at both ends and allows that floor's VLAN.
The 3560 Layer 3 switch uses switchport trunk encapsulation dot1q to select 802.1Q tagging. The 2960 does not require that command.
Each Layer 3 switch has an SVI for each floor VLAN. The SVI's address is the default gateway configured on that floor's PCs and printer.
ip routingenables routing between IP networks on the layer 3 switch.interface vlan 10selects the logical gateway interface for VLAN 10.ip addressassigns the gateway address and mask.no shutdownenables the interface administratively.
The same configuration pattern is applied to Business, Medicine, and Art using their floor gateway addresses.
Each Layer 3 switch connects to its building router through a routed physical interface. These links use the separate /30 transit subnets.
no switchport converts the port into a routed interface so it can hold an IP address directly.
The router does not use floor VLAN subinterfaces. Inter-VLAN routing remains on the building switch.
To verify thaty the connection was successful, I pinged Engineering's router from the layer 3 switch.
Each inter-router link uses its own subnet.
All six direct router-link tests completed successfully:
| Source router | Neighbor | Ping destination |
|---|---|---|
| Engineering | Medicine | 192.168.100.2 |
| Engineering | Business | 192.168.100.6 |
| Engineering | Art | 192.168.100.18 |
| Business | Art | 192.168.100.10 |
| Medicine | Art | 192.168.100.14 |
| Medicine | Business | 192.168.100.22 |
OSPF runs on the four routers and four Layer 3 switches in area 0. The building switches advertise the floor subnets, and the routers exchange reachability across the campus backbone.
On a PC from each school block, I used the ping command in command prompt to test PC and printer reachability. For example, from an Engineering PC:
ping 10.1.20.2
ping 10.2.40.2
ping 10.3.70.2
ping 10.4.100.2
ping 10.4.120.8
A successful ping confirms IP reachability and a working return path. An initial ping can lose a packet while ARP resolves an address, this is what caused some of the pings to be (25% lost).
Confirm that an Engineering PC can still reach a Medicine PC after the direct Engineering–Medicine router link is disabled.
- Verify baseline reachability from Engineering to the Medicine PC.
- Confirm Engineering's
GigabitEthernet0/0/0has address192.168.100.1. - Disable that interface only.
- Allow OSPF to converge and repeat the ping.
- Restore the interface and verify neighbor recovery.
Baseline test from the Engineering PC:
ping 10.3.70.2
On Engineering's router, simulate the failure:
enable
configure terminal
interface gigabitEthernet 0/0/0
shutdown
end
shutdown disables the port without deleting its address or OSPF settings.
After allowing time for convergence, repeat the ping. The path can also be inspected from the PC:
tracert 10.3.70.2
Restore the link:
configure terminal
interface gigabitEthernet 0/0/0
no shutdown
end
Verify the restored interface and adjacencies:
show ip interface brief
show ip ospf neighbor
The interface should return to up/up, and Engineering's router should return to four FULL neighbors after convergence.
The test results are of the first ping and tracert command after disabling the port between Engineering and Medicine routers. In the tracert, the route takes a different path instead of the original path which was directly to the School of Medicine Router (192.168.100.2). It took an alternate rout which is the School of Art router (192.168.100.18) then to the Engineering router (192.168.100.21).
The alternate-path test succeeded: communication worked after the direct Engineering–Medicine link was disabled. This demonstrated OSPF recovery through another campus path. Exact convergence time, packet loss during recovery, and the selected alternate path were not recorded.
This test demonstrates resilience to the tested inter-router link failure. It does not establish uninterrupted service or resilience to every possible device failure.
The completed configuration includes:
- Four schools with three floor networks each.
- Twelve VLANs with /28 floor subnets.
- Access-port assignments and restricted floor trunks.
- SVI gateways and inter-VLAN routing on four Layer 3 switches.
- Four dedicated switch-to-router /30 transit networks.
- A full mesh of four routers using six /30 inter-router networks.
- Single-area OSPF across the routers and building switches.
- Successful tests of all six direct router links.
- A successful alternate-path test after disabling the Engineering–Medicine link.
The project helped me distinguish between physical ports and VLAN interfaces, access links and trunks, and switching and routing roles. It also demonstrated why routers need routes to both the destination and the return network, and how OSPF can adapt when a link becomes unavailable.