CCNA Project part 2
Multi-Site Enterprise Network Build – Part 2
VLANs, DHCP, Inter-VLAN Routing, OSPF & Wireless Deployment
Welcome to Part 2 of my multi-site enterprise network project.
This phase focused on switching, VLAN design, DHCP, routing verification and wireless integration across HQ, Office 1 and Office 2. The goal was to build a realistic CCNA-level multi-site network that could also demonstrate my infrastructure understanding for job interviews.
1. VLAN Architecture & Switch Configuration
Each site uses the same standardised VLAN model:
| VLAN | Purpose | Subnet (HQ Example) |
|---|---|---|
| 10 | Users | 10.10.10.0/24 |
| 20 | Management | 10.10.20.0/24 |
| 30 | Corporate WiFi | 10.10.30.0/24 |
| 40 | Guest WiFi | 10.10.40.0/24 |
| 50 | Voice | 10.10.50.0/24 |
| 99 | Native VLAN | 10.10.99.0/24 |
All VLAN gateways and inter-VLAN routing are handled on the Layer 3 switch at each site.
Access switches (L2) provide end-user connectivity and uplink to the L3 switch over 802.1Q trunks.
Key Tasks Completed
- Created consistent VLANs on all L2 and L3 switches
- Configured SVIs on L3 switches with correct gateway IPs
- Set up trunk links (tagged VLANs + native VLAN 99)
- Cleaned VLAN database (vlan.dat) to remove corruption
- Fixed trunk port mismatches between L2 ↔ L3
- Restored proper access port behaviour for PCs, phones & APs
This resulted in a clean, stable VLAN and spanning-tree topology.
2. DHCP Relay (ip helper-address)
A central DHCP server at HQ provides IP addressing for every VLAN at every site.
To support this, each L3 switch uses DHCP relay:
interface Vlan10
ip helper-address 10.10.20.10
This was applied to all VLAN interfaces (10,20,30,40,50).
After fixing trunking issues and VLAN mismatches, DHCP successfully worked across all sites.
3. OSPF Routing Between Sites
OSPF Area 0 connects all three locations:
- HQ ↔ Office 1 (WAN1: 10.255.1.0/30)
- Office 1 ↔ Office 2 (WAN2: 10.255.2.0/30)
Key configuration points:
- All L3 switches use passive interfaces on VLAN SVIs
- Only router-to-router links form adjacencies
- HQ router performs NAT and default route to the internet
- L3 switches advertise all internal networks to OSPF
Example router output confirming adjacency:
HQ-Router# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/DR … 10.255.1.1 Gi0/2
2.2.2.2 1 FULL/BDR … 10.255.2.1 Gi0/0
Routing tables across all devices show correct inter-site reachability.
4. Wireless Networks – Corporate & Guest
Each site includes two APs:
- Corporate WiFi (VLAN 30)
- Guest WiFi (VLAN 40)
Packet Tracer APs require specific handling:
- Disable WAN/Internet interface
- Use LAN/Ethernet port only
- Static IP matching the VLAN
- Disable AP DHCP service
Once corrected, wireless clients:
- Receive correct DHCP scopes
- Use the correct default gateway
- Gain internet access (NAT via HQ router)
- Remain isolated between Corporate ↔ Guest networks
This mirrors a realistic enterprise WLAN deployment model.
5. End-to-End Testing Completed
User VLAN clients obtain correct DHCP leases
Inter-VLAN routing works at all sites
OSPF routes visible across HQ, Office 1, Office 2
Internet access from all internal networks
Wireless corporate & guest networks functioning
Voice VLANs registered & reachable (CCNA-level simulation)
Documentation Added
During this phase, I produced:
- VLAN & IP addressing plan (Excel)
- Trunk port mapping and interface-level documentation
- DHCP scope definition for all sites
- OSPF neighbour tables & routing verification
- AP configuration records
- Troubleshooting notes (native VLAN mismatch, DHCP relay issues, port reset behaviour, etc.)
This documentation is ready for inclusion in a CV, portfolio or interview presentation.
Part 3 — Coming Soon
In Part 3, I will cover: