DHCP configuration two routers with serial cable with commands 2025
DHCP configuration two routers with serial cable with commands 2025 DHCP configuration two routers with serial cable with commands 2025
🔹 DHCP Configuration on Two Routers Using Serial Cable (2025 Complete Guide)
DHCP configuration two routers with serial cable with commands 2025DHCP (Dynamic Host Configuration Protocol)
is a network protocol used to automatically assign IP address information to devices on a network.
Instead of manually configuring IP details on every device, DHCP does it automatically and dynamically.
🔹 Why DHCP is Needed
DHCP configuration two routers with serial cable
Without DHCP, you must manually enter:
- IP address
- Subnet mask
- Default gateway
- DNS server
This is time-consuming and error-prone, especially in large networks.
DHCP solves this by assigning everything automatically ✅
🔹 What DHCP Provides
A DHCP server assigns the following to clients:
- IP Address
- Subnet Mask
- Default Gateway
- DNS Server
- Lease Time
🔹 How DHCP Works (DORA Process)
DHCP configuration two routers with serial cable
DHCP follows a 4-step process called DORA:
- D – Discover
Client broadcasts: “Is there any DHCP server?” - O – Offer
DHCP server replies with an available IP address - R – Request
Client requests the offered IP address - A – Acknowledge
Server confirms and assigns the IP address
📌 After this, the device can communicate on the network.
🔹 Types of DHCP Assignment
DHCP configuration two routers with serial cable
- Dynamic Allocation – IP is assigned temporarily (most common)
- Automatic Allocation – Permanent IP after first assignment
- Manual Allocation (Reservation) – Same IP based on MAC address
🔹 DHCP Components
DHCP configuration two routers with serial cable
- DHCP Server – Assigns IP addresses (Router, Server)
- DHCP Client – Device requesting IP (PC, Mobile)
- DHCP Pool (Scope) – Range of IP addresses
- Lease Time – Duration IP is valid
🔹 Example
A router configured as DHCP server:
IP Range: 192.168.1.10 – 192.168.1.100
Subnet Mask: 255.255.255.0
Gateway: 192.168.1.1
DNS: 8.8.8.8
When a laptop connects, it automatically receives these details.
🔹 Advantages of DHCP
✔ Automatic IP assignment
✔ Saves time
✔ Reduces configuration errors
✔ Ideal for large networks
🔹 Where DHCP is Used
- Home networks (Wi-Fi routers)
- Office networks
- Enterprise networks
- ISPs
🔹 DHCP vs Static IP
| DHCP | Static IP |
|---|---|
| Automatic | Manual |
| Easy to manage | More control |
| IP may change | IP is fixed |
If you want, I can also explain:
- DHCP configuration on Cisco routers
- DHCP with two or three routers
- DHCP troubleshooting
- DHCP interview questions
Just tell me 👍
📌 INTRODUCTION
DHCP (Dynamic Host Configuration Protocol)
automatically assigns:
- IP Address
- Subnet Mask
- Default Gateway
- DNS Server
to client devices (PCs, laptops, mobiles).
In this lab:
- Router1 (R1) → DHCP Server for LAN1
- Router2 (R2) → DHCP Server for LAN2
- R1 and R2 connected using Serial Cable
- Static IP routing used between routers
🖧 NETWORK TOPOLOGY
PC1 ---- Switch ---- R1 ===== Serial Cable ===== R2 ---- Switch ---- PC2
📊 IP ADDRESSING PLAN
🔹 LAN 1 (Router 1 Side)
| Device | IP |
|---|---|
| Network | 192.168.10.0/24 |
| R1 LAN | 192.168.10.1 |
| PC1 | DHCP |
🔹 LAN 2 (Router 2 Side)
| Device | IP |
|---|---|
| Network | 192.168.20.0/24 |
| R2 LAN | 192.168.20.1 |
| PC2 | DHCP |
🔹 Serial Link
| Link | IP |
|---|---|
| R1 Serial | 10.10.10.1/30 |
| R2 Serial | 10.10.10.2/30 |
🧰 REQUIRED DEVICES
- 2 Routers (Cisco 2811 / 1941)
- 2 Switches
- 2 PCs
- 1 Serial DCE Cable
- 2 Copper Straight-Through Cables
🔧 STEP 1: BASIC CONFIGURATION ON ROUTER 1
DHCP configuration two routers with serial cable
🔹 Enter Privileged Mode
Router> enable
Router# configure terminal
🔹 Set Hostname
Router(config)# hostname R1
🔧 STEP 2: CONFIGURE LAN INTERFACE ON R1
R1(config)# interface fastEthernet0/0
R1(config-if)# ip address 192.168.10.1 255.255.255.0
R1(config-if)# no shutdown
R1(config-if)# exit
🔧 STEP 3: CONFIGURE SERIAL INTERFACE ON R1
R1(config)# interface serial0/0/0
R1(config-if)# ip address 10.10.10.1 255.255.255.252
R1(config-if)# clock rate 64000
R1(config-if)# no shutdown
R1(config-if)# exit
⚠️ Clock rate is required only on DCE side
🔧 STEP 4: CONFIGURE DHCP SERVER ON ROUTER 1
🔹 Exclude Router IP
R1(config)# ip dhcp excluded-address 192.168.10.1 192.168.10.10
🔹 Create DHCP Pool
R1(config)# ip dhcp pool LAN1
R1(dhcp-config)# network 192.168.10.0 255.255.255.0
R1(dhcp-config)# default-router 192.168.10.1
R1(dhcp-config)# dns-server 8.8.8.8
R1(dhcp-config)# domain-name lan1.local
R1(dhcp-config)# exit
🔧 STEP 5: BASIC CONFIGURATION ON ROUTER 2
Router> enable
Router# configure terminal
Router(config)# hostname R2
🔧 STEP 6: CONFIGURE LAN INTERFACE ON R2
R2(config)# interface fastEthernet0/0
R2(config-if)# ip address 192.168.20.1 255.255.255.0
R2(config-if)# no shutdown
R2(config-if)# exit
🔧 STEP 7: CONFIGURE SERIAL INTERFACE ON R2
R2(config)# interface serial0/0/0
R2(config-if)# ip address 10.10.10.2 255.255.255.252
R2(config-if)# no shutdown
R2(config-if)# exit
🔧 STEP 8: CONFIGURE DHCP SERVER ON ROUTER 2
🔹 Exclude Gateway IP
R2(config)# ip dhcp excluded-address 192.168.20.1 192.168.20.10
🔹 Create DHCP Pool
R2(config)# ip dhcp pool LAN2
R2(dhcp-config)# network 192.168.20.0 255.255.255.0
R2(dhcp-config)# default-router 192.168.20.1
R2(dhcp-config)# dns-server 8.8.4.4
R2(dhcp-config)# domain-name lan2.local
R2(dhcp-config)# exit
🔧 STEP 9: CONFIGURE STATIC ROUTING
🔹 On Router 1
R1(config)# ip route 192.168.20.0 255.255.255.0 10.10.10.2
🔹 On Router 2
R2(config)# ip route 192.168.10.0 255.255.255.0 10.10.10.1
🖥️ STEP 10: CONFIGURE PCs FOR DHCP
🔹 PC1
Desktop → IP Configuration → DHCP
🔹 PC2
Desktop → IP Configuration → DHCP
✔ PCs will automatically receive:
- IP Address
- Gateway
- DNS
🔍 STEP 11: VERIFICATION COMMANDS
🔹 Check Interface Status
show ip interface brief
🔹 Check DHCP Bindings
show ip dhcp binding
🔹 Check DHCP Pool
show ip dhcp pool
🔄 STEP 12: TEST CONNECTIVITY
🔹 From PC1
ping 192.168.20.1
ping 192.168.20.X
🔹 From PC2
ping 192.168.10.1
✔ If ping replies → DHCP + Routing SUCCESSFUL
⚠️ COMMON TROUBLESHOOTING
| Problem | Solution |
|---|---|
| No IP to PC | Check DHCP pool |
| Serial down | Check clock rate |
| No ping | Check static routes |
| Wrong IP | Check excluded range |
| DHCP not working | service dhcp |
Enable DHCP service if disabled:
service dhcp
📘 IMPORTANT INTERVIEW QUESTIONS
- Difference between DHCP Server and Relay
- What is excluded-address?
- Why clock rate is used?
- DHCP DORA process
- Static vs Dynamic Routing
🏁 CONCLUSION
In this 2025 DHCP two-router serial cable configuration, you learned:
✔ Router-based DHCP
✔ Serial link configuration
✔ Static routing
✔ DHCP verification
✔ Real-world troubleshooting
This setup is 100% valid for CCNA, labs, exams, and blog tutorials.
If you want:
example
- Configure ip address only on router and enable routing
- On r0
Router(config)#ip dhcp pool aaa
Router(dhcp-config)#network 10.0.0.0 255.0.0.0
Router(dhcp-config)#default-router 10.0.0.1
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 10.0.0.3 10.0.0.7
- Go to system and obtain ip automatically.
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