how to configured three router dynamic ip address with serial port with command prompt 2026
How to Configure Three Routers with Dynamic IP Address Using Serial Port (2026 Guide)
Website: https://sreekrishnatechbloganantapur2026.blogspot.com/
Email: pgollabala@gmail.com
Introduction
Configuring multiple routers with dynamic IP addressing is an essential skill in networking, especially for students, IT professionals, and beginners preparing for networking jobs. In this guide, you will learn how to configure three routers using serial ports with dynamic IP addresses (DHCP) using command-line interface (CLI).
This tutorial is simple, practical, and designed for Cisco Packet Tracer / real routers, helping you understand real-world networking concepts.
Network Topology
We will configure 3 routers connected via serial cables:
Router1 ---- Router2 ---- Router3
Router1 connected to Router2 via Serial
Router2 connected to Router3 via Serial
Each router will use dynamic IP (DHCP) for LAN
Routing will be configured for communication
Requirements
3 Routers (Cisco 1941 or similar)
Serial DCE/DTE cables
PC or Laptop
Cisco Packet Tracer (for simulation)
Step 1: Basic Configuration on All Routers
Enter privileged mode:
enable
configure terminal
Set hostname:
Router1
hostname R1
Router2
hostname R2
Router3
hostname R3
Step 2: Configure Serial Interfaces
Router1 (R1)
interface serial 0/0/0
ip address 10.0.0.1 255.255.255.252
clock rate 64000
no shutdown
Router2 (R2)
interface serial 0/0/0
ip address 10.0.0.2 255.255.255.252
no shutdown
interface serial 0/0/1
ip address 10.0.0.5 255.255.255.252
clock rate 64000
no shutdown
Router3 (R3)
interface serial 0/0/0
ip address 10.0.0.6 255.255.255.252
no shutdown
Step 3: Configure LAN Interfaces
Router1 LAN
interface gigabitEthernet 0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
Router2 LAN
interface gigabitEthernet 0/0
ip address 192.168.2.1 255.255.255.0
no shutdown
Router3 LAN
interface gigabitEthernet 0/0
ip address 192.168.3.1 255.255.255.0
no shutdown
Step 4: Configure DHCP (Dynamic IP Address)
Router1 DHCP
ip dhcp pool LAN1
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 8.8.8.8
Router2 DHCP
ip dhcp pool LAN2
network 192.168.2.0 255.255.255.0
default-router 192.168.2.1
dns-server 8.8.8.8
Router3 DHCP
ip dhcp pool LAN3
network 192.168.3.0 255.255.255.0
default-router 192.168.3.1
dns-server 8.8.8.8
Step 5: Configure Routing (Static Routing)
Router1
ip route 192.168.2.0 255.255.255.0 10.0.0.2
ip route 192.168.3.0 255.255.255.0 10.0.0.2
Router2
ip route 192.168.1.0 255.255.255.0 10.0.0.1
ip route 192.168.3.0 255.255.255.0 10.0.0.6
Router3
ip route 192.168.1.0 255.255.255.0 10.0.0.5
ip route 192.168.2.0 255.255.255.0 10.0.0.5
Step 6: Save Configuration
Run this command on all routers:
write memory
OR
copy running-config startup-config
Step 7: Testing Connectivity
From PC connected to Router1:
ping 192.168.2.1
ping 192.168.3.1
If configuration is correct, all routers will communicate successfully.
Common Errors & Fixes
1. Interface Down
Use:
no shutdown
2. Wrong Cable (Serial)
Ensure DCE side has:
clock rate 64000
3. DHCP Not Working
Check:
show ip dhcp binding
Advantages of Dynamic IP Configuration
Automatic IP assignment
Easy network management
Reduces manual errors
Ideal for large networks
router CLI commands step by step
Cisco Packet Tracer router setup
Conclusion
In this tutorial, you learned how to configure three routers with dynamic IP addressing using serial connections and CLI commands. This setup is very useful for networking labs, interviews, and real-world troubleshooting.
Practice this configuration multiple times to master networking concepts and improve your skills.
About Sree Krishna Tech Blog
For more tutorials on:
Networking
Computer Hardware
Troubleshooting
Online Earning
Visit: https://sreekrishnatechbloganantapur2026.blogspot.com/
Contact: pgollabala@gmail.com
Stay connected for more IT tutorials in 2026!
to read below as follow steps
Dynamic ip address configuration three routers with serial cable
router0
========
router>en
router#config t
router(config)#hostname r0
r0(config)#interface f0/0
r0(config-if)#ip add 10.0.0.1 255.0.0.0
r0(config-if)#no shutdown
r0(config-if)#exit
r0(config)#interface s1/0
ro(config-if)#ip add 20.0.0.1 255.0.0.0
r0(config-if)#clock rate 64000
r0(config-if)#no shutdown
r0(config-if)#exit
r0(config)#
routing part
=============
DYNAMIC IP ROUTING
RIP
Configure all ip address
R0
Router(config)#router rip
Router(config-router)#network 10.0.0.0
Router(config-router)#network 20.0.0.0
EIGRP
R0
Router(config)#router eigrp 10
Router(config-router)#net 10.0.0.0
Router(config-router)#net 20.0.0.0
OSPF
R0
Router(config)#router ospf 10
Router(config-router)#net 10.0.0.0 0.255.255.255 area 0
Router(config-router)#net 20.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. 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 10.0.0.1
3. Go to system and obtain ip automatically.
router1
================
router>en
router#config t
router(config)#hostname r1
r1(config)#interface f0/0
r1(config-if)#ip add 20.0.0.1 255.0.0.0
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#interface s1/0
r1(config-if)#ip add 20.0.0.2 255.0.0.0
r1(config)#interface s1/1
r1(config-if)#ip add 40.0.0.2 255.0.0.0
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#
routing part
=============
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#
routing part
=============
DYNAMIC IP ROUTING
RIP
Configure all ip address
R1
Router(config-if)#router rip
Router(config-router)#network 20.0.0.0
Router(config-router)#network 30.0.0.0
Router(config-router)#network 40.0.0.0
EIGRP
R1
Router(config-if)#router eigrp 10
Router(config-router)#network 20.0.0.0
Router(config-router)#network 30.0.0.0
Router(config-router)#network 40.0.0.0
OSPF
R1
Router(config)#router ospf 10
Router(config-router)#net 20.0.0.0 0.255.255.255 area 0
Router(config-router)#net 30.0.0.0 0.255.255.255 area 0
Router(config-router)#net 40.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. On r1
Router(config)#ip dhcp pool aaa
Router(dhcp-config)#network 30.0.0.0 255.0.0.0
Router(dhcp-config)#default-router 30.0.0.1
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 30.0.0.1
3. Go to system and obtain ip automatically.
router2
================
router>en
router#config t
router(config)#hostname r2
r2(config)#interface f0/0
r2(config-if)#ip add 20.0.0.1 255.0.0.0
r2(config-if)#no shutdown
r2(config-if)#exit
r2(config)#interface s1/0
r2(config-if)#ip add 40.0.0.2 255.0.0.0
r2(config-if)#no shutdown
r2(config-if)#exit
r2(config)#
routing part
=============
Dynamic Routing
RIP
R2
Router(config-if)#router rip
Router(config-router)#net 40.0.0.0
Router(config-router)#net 50.0.0.0
EIGRP
R2
Router(config-if)#router eigrp 10
Router(config-router)#net 40.0.0.0
Router(config-router)#net 50.0.0.0
OSPF
R2
Router(config)#router ospf 10
Router(config-router)#net 40.0.0.0 0.255.255.255 area 0
Router(config-router)#net 50.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. On r1
Router(config)#ip dhcp pool aaa
Router(dhcp-config)#network 50.0.0.0 255.0.0.0
Router(dhcp-config)#default-router 50.0.0.1
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 30.0.0.1
3. Go to system and obtain ip automatically.
Default routing
R1
Router(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.2
R2
Router(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.1
Router(config)#ip route 0.0.0.0 0.0.0.0 40.0.0.2
R3
Router(config)#ip route 0.0.0.0 0.0.0.0 40.0.0.1
switch configuration
cisco 2950 switch configuration
sw 0
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name admin
Switch(vlan)#vlan 20 name mark
Switch#sh vlan
Switch#conf t
Switch(config)#int f0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/2
Switch#exit
sw 1
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name hr
Switch(vlan)#vlan 20 name agents
Switch#sh vlan
Switch#conf t
Switch(config)#int f0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/2
Switch#exit
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How to Configure Three Routers with Dynamic IP Address Using Serial Port (2026 Guide)
Website: https://sreekrishnatechbloganantapur2026.blogspot.com/
Email: pgollabala@gmail.com
Introduction
Configuring multiple routers with dynamic IP addressing is an essential skill in networking, especially for students, IT professionals, and beginners preparing for networking jobs. In this guide, you will learn how to configure three routers using serial ports with dynamic IP addresses (DHCP) using command-line interface (CLI).
This tutorial is simple, practical, and designed for Cisco Packet Tracer / real routers, helping you understand real-world networking concepts.
Network Topology
We will configure 3 routers connected via serial cables:
Router1 ---- Router2 ---- Router3
Router1 connected to Router2 via Serial
Router2 connected to Router3 via Serial
Each router will use dynamic IP (DHCP) for LAN
Routing will be configured for communication
Requirements
3 Routers (Cisco 1941 or similar)
Serial DCE/DTE cables
PC or Laptop
Cisco Packet Tracer (for simulation)
Step 1: Basic Configuration on All Routers
Enter privileged mode:
enable
configure terminal
Set hostname:
Router1
hostname R1
Router2
hostname R2
Router3
hostname R3
Step 2: Configure Serial Interfaces
Router1 (R1)
interface serial 0/0/0
ip address 10.0.0.1 255.255.255.252
clock rate 64000
no shutdown
Router2 (R2)
interface serial 0/0/0
ip address 10.0.0.2 255.255.255.252
no shutdown
interface serial 0/0/1
ip address 10.0.0.5 255.255.255.252
clock rate 64000
no shutdown
Router3 (R3)
interface serial 0/0/0
ip address 10.0.0.6 255.255.255.252
no shutdown
Step 3: Configure LAN Interfaces
Router1 LAN
interface gigabitEthernet 0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
Router2 LAN
interface gigabitEthernet 0/0
ip address 192.168.2.1 255.255.255.0
no shutdown
Router3 LAN
interface gigabitEthernet 0/0
ip address 192.168.3.1 255.255.255.0
no shutdown
Step 4: Configure DHCP (Dynamic IP Address)
Router1 DHCP
ip dhcp pool LAN1
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 8.8.8.8
Router2 DHCP
ip dhcp pool LAN2
network 192.168.2.0 255.255.255.0
default-router 192.168.2.1
dns-server 8.8.8.8
Router3 DHCP
ip dhcp pool LAN3
network 192.168.3.0 255.255.255.0
default-router 192.168.3.1
dns-server 8.8.8.8
Step 5: Configure Routing (Static Routing)
Router1
ip route 192.168.2.0 255.255.255.0 10.0.0.2
ip route 192.168.3.0 255.255.255.0 10.0.0.2
Router2
ip route 192.168.1.0 255.255.255.0 10.0.0.1
ip route 192.168.3.0 255.255.255.0 10.0.0.6
Router3
ip route 192.168.1.0 255.255.255.0 10.0.0.5
ip route 192.168.2.0 255.255.255.0 10.0.0.5
Step 6: Save Configuration
Run this command on all routers:
write memory
OR
copy running-config startup-config
Step 7: Testing Connectivity
From PC connected to Router1:
ping 192.168.2.1
ping 192.168.3.1
If configuration is correct, all routers will communicate successfully.
Common Errors & Fixes
1. Interface Down
Use:
no shutdown
2. Wrong Cable (Serial)
Ensure DCE side has:
clock rate 64000
3. DHCP Not Working
Check:
show ip dhcp binding
Advantages of Dynamic IP Configuration
Automatic IP assignment
Easy network management
Reduces manual errors
Ideal for large networks
router CLI commands step by step
Cisco Packet Tracer router setup
Conclusion
In this tutorial, you learned how to configure three routers with dynamic IP addressing using serial connections and CLI commands. This setup is very useful for networking labs, interviews, and real-world troubleshooting.
Practice this configuration multiple times to master networking concepts and improve your skills.
About Sree Krishna Tech Blog
For more tutorials on:
Networking
Computer Hardware
Troubleshooting
Online Earning
Visit: https://sreekrishnatechbloganantapur2026.blogspot.com/
Contact: pgollabala@gmail.com
Stay connected for more IT tutorials in 2026!
to read below as follow steps
Dynamic ip address configuration three routers with serial cable
router0
========
router>en
router#config t
router(config)#hostname r0
r0(config)#interface f0/0
r0(config-if)#ip add 10.0.0.1 255.0.0.0
r0(config-if)#no shutdown
r0(config-if)#exit
r0(config)#interface s1/0
ro(config-if)#ip add 20.0.0.1 255.0.0.0
r0(config-if)#clock rate 64000
r0(config-if)#no shutdown
r0(config-if)#exit
r0(config)#
routing part
=============
DYNAMIC IP ROUTING
RIP
Configure all ip address
R0
Router(config)#router rip
Router(config-router)#network 10.0.0.0
Router(config-router)#network 20.0.0.0
EIGRP
R0
Router(config)#router eigrp 10
Router(config-router)#net 10.0.0.0
Router(config-router)#net 20.0.0.0
OSPF
R0
Router(config)#router ospf 10
Router(config-router)#net 10.0.0.0 0.255.255.255 area 0
Router(config-router)#net 20.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. 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 10.0.0.1
3. Go to system and obtain ip automatically.
router1
================
router>en
router#config t
router(config)#hostname r1
r1(config)#interface f0/0
r1(config-if)#ip add 20.0.0.1 255.0.0.0
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#interface s1/0
r1(config-if)#ip add 20.0.0.2 255.0.0.0
r1(config)#interface s1/1
r1(config-if)#ip add 40.0.0.2 255.0.0.0
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#
routing part
=============
r1(config-if)#no shutdown
r1(config-if)#exit
r1(config)#
routing part
=============
DYNAMIC IP ROUTING
RIP
Configure all ip address
R1
Router(config-if)#router rip
Router(config-router)#network 20.0.0.0
Router(config-router)#network 30.0.0.0
Router(config-router)#network 40.0.0.0
EIGRP
R1
Router(config-if)#router eigrp 10
Router(config-router)#network 20.0.0.0
Router(config-router)#network 30.0.0.0
Router(config-router)#network 40.0.0.0
OSPF
R1
Router(config)#router ospf 10
Router(config-router)#net 20.0.0.0 0.255.255.255 area 0
Router(config-router)#net 30.0.0.0 0.255.255.255 area 0
Router(config-router)#net 40.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. On r1
Router(config)#ip dhcp pool aaa
Router(dhcp-config)#network 30.0.0.0 255.0.0.0
Router(dhcp-config)#default-router 30.0.0.1
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 30.0.0.1
3. Go to system and obtain ip automatically.
router2
================
router>en
router#config t
router(config)#hostname r2
r2(config)#interface f0/0
r2(config-if)#ip add 20.0.0.1 255.0.0.0
r2(config-if)#no shutdown
r2(config-if)#exit
r2(config)#interface s1/0
r2(config-if)#ip add 40.0.0.2 255.0.0.0
r2(config-if)#no shutdown
r2(config-if)#exit
r2(config)#
routing part
=============
Dynamic Routing
RIP
R2
Router(config-if)#router rip
Router(config-router)#net 40.0.0.0
Router(config-router)#net 50.0.0.0
EIGRP
R2
Router(config-if)#router eigrp 10
Router(config-router)#net 40.0.0.0
Router(config-router)#net 50.0.0.0
OSPF
R2
Router(config)#router ospf 10
Router(config-router)#net 40.0.0.0 0.255.255.255 area 0
Router(config-router)#net 50.0.0.0 0.255.255.255 area 0
DHCP
1. Configure ip address only on router and enable routing
2. On r1
Router(config)#ip dhcp pool aaa
Router(dhcp-config)#network 50.0.0.0 255.0.0.0
Router(dhcp-config)#default-router 50.0.0.1
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 30.0.0.1
3. Go to system and obtain ip automatically.
Default routing
R1
Router(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.2
R2
Router(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.1
Router(config)#ip route 0.0.0.0 0.0.0.0 40.0.0.2
R3
Router(config)#ip route 0.0.0.0 0.0.0.0 40.0.0.1
switch configuration
cisco 2950 switch configuration
sw 0
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name admin
Switch(vlan)#vlan 20 name mark
Switch#sh vlan
Switch#conf t
Switch(config)#int f0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/2
Switch#exit
sw 1
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name hr
Switch(vlan)#vlan 20 name agents
Switch#sh vlan
Switch#conf t
Switch(config)#int f0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#int f0/2
Switch#exit
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