- 📘 Project Overview
- 🎯 Project Objective
- 🌐 Network Topology
- 🖧 Device Interface Table
- 📝 IP Addressing Table
- 🔧 Lab Steps
- 💻 Device Configuration
- 🧰 Packet Tracer Limitations
- ✅ Verification
- ⚡ How to Run Lab
- 📂 -Folder Structure
- 🎓 Learning Outcomes
- ℹ️ Repository Info
This lab demonstrates DHCP redundancy in a small office network. Two DHCP servers provide IP addresses to PCs across VLANs. If the primary DHCP server fails, the backup server ensures continued IP availability. The lab also demonstrates router-on-a-stick configuration for inter-VLAN communication.
Note: Due to Packet Tracer simulation limitations, DHCP may not function correctly in multi-VLAN setups with router-on-a-stick. Manual IP assignment was used for demonstration purposes to verify the lab objectives, including inter-VLAN communication and DHCP failover.
- Configure DHCP pools on a primary server for VLAN10 and VLAN20.
- Configure a backup DHCP server to provide failover.
- Verify inter-VLAN communication using a router-on-a-stick.
- Demonstrate DHCP failover scenario.
- Document Packet Tracer limitations and provide workarounds.
- Devices: 2 DHCP Servers, 1 Router (R1), 2 Switches (SW1, SW2), 6 PCs
- VLAN Assignment:
- VLAN10: PC1, PC2, PC5
- VLAN20: PC3, PC4, PC6
| Device | Interface | Connected Device | Connected Interface | VLAN / Notes |
|---|---|---|---|---|
| Router | G0/0 | Switch 1 | Fa0/24 | Trunk / VLAN 10 & 20 |
| Switch1 | Fa0/1 | PC1 | NIC | VLAN10 |
| Switch1 | Fa0/2 | PC2 | NIC | VLAN10 |
| Switch1 | Fa0/3 | PC3 | NIC | VLAN20 |
| Switch1 | Fa0/4 | DHCP Server1 | NIC | VLAN10 |
| Switch1 | Fa0/5 | DHCP Server2 | NIC | VLAN10 (backup) |
| Switch1 | Fa0/23 | Switch2 | Fa0/23 | Trunk / inter-switch link |
| Switch1 | Fa0/24 | Router G0/0 | G0/0 | Trunk / VLAN 10 & 20 |
| Switch2 | Fa0/1 | PC4 | NIC | VLAN20 |
| Switch2 | Fa0/2 | PC5 | NIC | VLAN10 |
| Switch2 | Fa0/3 | PC6 | NIC | VLAN20 |
| Switch2 | Fa0/23 | Switch1 | Fa0/23 | Trunk / inter-switch link |
| Device / VLAN | IP Address (Planned DHCP Pool) | Subnet Mask | Default Gateway | Notes / Verification Workaround |
|---|---|---|---|---|
| PC1 (VLAN10) | 192.168.10.50–100 (DHCP) | 255.255.255.0 | 192.168.10.1 | Manual IP assigned due to PT limitation |
| PC2 (VLAN10) | 192.168.10.50–100 (DHCP) | 255.255.255.0 | 192.168.10.1 | Manual IP assigned for verification |
| PC5 (VLAN10) | 192.168.10.50–100 (DHCP) | 255.255.255.0 | 192.168.10.1 | Manual IP assigned for verification |
| PC3 (VLAN20) | 192.168.20.50–100 (DHCP) | 255.255.255.0 | 192.168.20.1 | Manual IP assigned for verification |
| PC4 (VLAN20) | 192.168.20.50–100 (DHCP) | 255.255.255.0 | 192.168.20.1 | Manual IP assigned for verification |
| PC6 (VLAN20) | 192.168.20.50–100 (DHCP) | 255.255.255.0 | 192.168.20.1 | Manual IP assigned for verification |
| Router G0/0.10 | 192.168.10.1 | 255.255.255.0 | - | VLAN10 SVI for DHCP gateway |
| Router G0/0.20 | 192.168.20.1 | 255.255.255.0 | - | VLAN20 SVI for DHCP gateway |
| Server1 VLAN10 | 192.168.10.10 | 255.255.255.0 | 192.168.10.1 | Primary DHCP server |
| Server2 VLAN10 | 192.168.10.11 | 255.255.255.0 | 192.168.10.1 | Backup DHCP server, used for failover |
Note: Manual IP assignment was used for verification due to Packet Tracer DHCP limitations.
- Configure VLANs on SW1 and SW2.
- Configure router-on-a-stick (R1 subinterfaces) for VLAN10 & VLAN20.
- Configure primary DHCP server with pools for VLAN10 and VLAN20.
- Configure backup DHCP server with pools for VLAN10 and VLAN20 (keep OFF initially).
- Connect PCs to respective VLAN ports.
- Assign trunk links between switches and router.
- Verify inter-VLAN routing and DHCP assignment (manual IP assignment if PT fails).
- Simulate failover: turn off Server1, turn on Server2, assign backup IPs, test connectivity.
vlan 10
name HR
exit
vlan 20
name IT
exit
! Assign access ports
interface fa0/1
switchport mode access
switchport access vlan 10
description PC1
exit
View Full Configuration File →
vlan 10
name HR
exit
vlan 20
name IT
exit
! Access ports for PCs
interface fa0/1
description PC4
switchport mode access
switchport access vlan 20
no shutdown
exit
View Full Configuration File →
interface GigabitEthernet0/0.10
description VLAN10 - HR
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
no shutdown
exit
View Full Configuration File →
Primary Server
Create Pool VLAN10-HR
- Default Gateway: 192.168.10.1
- Start IP: 192.168.10.50
- End IP: 192.168.10.100
- Subnet Mask: 255.255.255.0
Refer to full files:
Backup Server
Refer to full files:
-
DHCP in multi-VLAN topologies may:
-
Assign IP outside the DHCP pool
-
Fail to assign default gateway and DNS
-
Summary:
The DHCP issue occurs because Router-on-a-Stick with multiple VLANs in Packet Tracer cannot reliably forward DHCP requests/responses. Manual IP assignment was used to complete verification steps and demonstrate failover.
SW1> show vlan brief
SW2> show vlan brief
SW1
SW2
SW1> show interfaces trunk
SW2> show interfaces trunk
SW1
SW2
R1> show ip interface brief
R1
Note:
- PCs are intended to receive IPs dynamically from DHCP.
- Due to Packet Tracer limitation with multi-VLAN DHCP (router-on-a-stick), DHCP may fail to assign the correct IP, gateway, or DNS.
- Manual IPs within the DHCP pool were used for verification.
| PC | IP Address | Subnet Mask | Default Gateway |
|---|---|---|---|
| PC1 | 192.168.10.50 | 255.255.255.0 | 192.168.10.1 |
| PC3 | 192.168.20.50 | 255.255.255.0 | 192.168.20.1 |
PC1
PC3
PC1> ping 192.168.20.50
PC3> ping 192.168.10.50
PC1
PC3
- Turn Server1 OFF, Server2 ON.
- Assign backup IPs manually (Packet Tracer limitation)
PC1: 192.168.10.101
PC3: 192.168.20.101
PC1
PC3
- Verify connectivity to gateway:
PC1> ping 192.168.10.1
PC3> ping 192.168.20.1
PC1
PC3
PC1> ping 192.168.20.101
PC3> ping 192.168.10.101
PC1
PC2
-
Download or clone the repository.
-
Open Packet Tracer and load the lab file: lab_file/dhcp-redundancy-with-Failover-in-Office-Network.pkt
-
Load device configurations from the configs/ folder if needed.
-
Start all devices and verify VLANs, trunk links, and inter-VLAN routing.
-
Test DHCP assignment for PCs (manual IPs may be needed due to Packet Tracer limitations).
-
Simulate failover by turning off Server1 and assigning backup IPs via Server2.
-
Verify connectivity and inter-VLAN communication post-failover.
dhcp-redundancy-with-Failover-in-Office-Network/
├─ README.md
├─ LICENSE
├─ verification.md
├─ lab_file/
│ └─ dhcp-redundancy-with-Failover-in-Office-Network.pkt
├─ topology/
│ └─ topology_overview.png
├─ configs/
│ └─ router-config/
│ └─ r1.cfg
│ └─ switch-config/
│ ├─ sw1.cfg
│ └─ sw2.cfg
│ └─ server-config/
│ ├─ server1.text
│ └─ server2.txt
├─ screenshots/
│ ├─ pc1_failover_ip.png
│ ├─ pc1_ping_failover_gw.png
│ ├─ pc1_ping_vlan20.png
│ ├─ pc1_ping_vlan20_failover.png
│ ├─ pc1_vlan10_ip_assigned.png
│ ├─ pc3_failover_ip.png
│ ├─ pc3_ping_failover_gw.png
│ ├─ pc3_ping_vlan10.png
│ ├─ pc3_ping_vlan10_failover.png
│ ├─ r1_ip_brief.png
│ ├─ sw1_trunk_status.png
│ ├─ sw1_vlan_brief.png
│ ├─ sw2_trunk_status.png
│ └─ sw2_vlan_brief.png
│
After completing this lab, learners will be able to:
-
Configure VLANs and assign switch ports to the correct VLAN.
-
Set up a router-on-a-stick for inter-VLAN routing.
-
Configure primary and backup DHCP servers with failover pools.
-
Understand DHCP relay (IP helper-address) functionality for VLANs.
-
Test and verify DHCP assignment, network connectivity, and failover scenarios.
-
Document Packet Tracer limitations and implement manual workarounds.
-
Build a structured lab portfolio for CCNA practical assessments.
This project is part of my CCNA Lab Portfolio.
Explore more labs here 👉 @asmymhm