Here is a simple step-by-step DHCP configuration for three Cisco 1841 Integrated Services Router routers using dynamic IP addressing and static routing.
Network Topology
PC1 ---- R1 ---- R2 ---- R3 ---- PC2
IP Address Plan
| Device | Interface | IP Address |
|---|---|---|
| R1 | Fa0/0 | 192.168.1.1/24 |
| R1 | S0/0/0 | 10.0.12.1/30 |
| R2 | S0/0/0 | 10.0.12.2/30 |
| R2 | S0/0/1 | 10.0.23.1/30 |
| R3 | S0/0/1 | 10.0.23.2/30 |
| R3 | Fa0/0 | 192.168.3.1/24 |
PC1 gets IP from R1 DHCP
PC2 gets IP from R3 DHCP
Step 1: Connect Devices
Use:
Console cable for configuration
Serial DCE/DTE cable between routers
Straight-through cable from PC to router
Step 2: Configure Router R1
enable
configure terminal
hostname R1
interface fastethernet0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
interface serial0/0/0
ip address 10.0.12.1 255.255.255.252
clock rate 64000
no shutdown
Configure DHCP on R1
ip dhcp excluded-address 192.168.1.1 192.168.1.10
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
Static Route
ip route 192.168.3.0 255.255.255.0 10.0.12.2
Save
end
write memory
Step 3: Configure Router R2
enable
configure terminal
hostname R2
interface serial0/0/0
ip address 10.0.12.2 255.255.255.252
no shutdown
interface serial0/0/1
ip address 10.0.23.1 255.255.255.252
clock rate 64000
no shutdown
Static Routes
ip route 192.168.1.0 255.255.255.0 10.0.12.1
ip route 192.168.3.0 255.255.255.0 10.0.23.2
Save
end
write memory
Step 4: Configure Router R3
enable
configure terminal
hostname R3
interface fastethernet0/0
ip address 192.168.3.1 255.255.255.0
no shutdown
interface serial0/0/1
ip address 10.0.23.2 255.255.255.252
no shutdown
Configure DHCP on R3
ip dhcp excluded-address 192.168.3.1 192.168.3.10
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
Static Route
ip route 192.168.1.0 255.255.255.0 10.0.23.1
Save
end
write memory
Step 5: Configure PCs
PC1
Desktop → IP Configuration
Select:
DHCP
PC1 receives:
IP: 192.168.1.x
Gateway: 192.168.1.1
PC2
Desktop → IP Configuration
Select:
DHCP
PC2 receives:
IP: 192.168.3.x
Gateway: 192.168.3.1
Step 6: Verify Configuration
Check Interfaces
show ip interface brief
Check DHCP Bindings
show ip dhcp binding
Check Routing Table
show ip route
Test Connectivity
From PC1:
ping 192.168.3.1
From PC2:
ping 192.168.1.1
Expected Result
PCs automatically receive IP addresses
All three routers communicate successfully
Ping works between networks
DHCP works on both LANs
Optional Next Step
You can also configure:
RIP routing
OSPF routing
EIGRP
Telnet
ACL security
NAT
VLANs
on these three Cisco 1841 Integrated Services Router routers.