how to configured three routers cisco 1841 telnet configuration

how to configured three routers cisco 1841 telnet configuration 

Network Topology Example

Use 3 × Cisco 1841 routers.

Example connections:

• Router1 ↔ Router2

• Router2 ↔ Router3

IP Address Plan

Router	Interface	IP Address	Subnet Mask
R1	FastEthernet0/0	192.168.1.1	255.255.255.0
R1	Serial0/0/0	10.0.0.1	255.255.255.252
R2	Serial0/0/0	10.0.0.2	255.255.255.252
R2	Serial0/0/1	10.0.0.5	255.255.255.252
R3	Serial0/0/0	10.0.0.6	255.255.255.252
R3	FastEthernet0/0	192.168.3.1	255.255.255.0

---

Step 1: Connect Routers

Use:

• Console cable for initial setup

• Serial DCE/DTE cable between routers

• Ethernet cable for PC connections

---

Step 2: Configure Router 1 (R1)

enable
configure terminal

hostname R1

interface fastethernet0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
exit

interface serial0/0/0
ip address 10.0.0.1 255.255.255.252
clock rate 64000
no shutdown
exit

ip route 192.168.3.0 255.255.255.0 10.0.0.2

Configure Telnet on R1

line vty 0 4
password cisco
login
transport input telnet
exit

enable password class

Save configuration:

copy running-config startup-config

---

Step 3: Configure Router 2 (R2)

enable
configure terminal

hostname R2

interface serial0/0/0
ip address 10.0.0.2 255.255.255.252
no shutdown
exit

interface serial0/0/1
ip address 10.0.0.5 255.255.255.252
clock rate 64000
no shutdown
exit

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

Configure Telnet on R2

line vty 0 4
password cisco
login
transport input telnet
exit

enable password class

Save configuration:

copy running-config startup-config

---

Step 4: Configure Router 3 (R3)

enable
configure terminal

hostname R3

interface fastethernet0/0
ip address 192.168.3.1 255.255.255.0
no shutdown
exit

interface serial0/0/0
ip address 10.0.0.6 255.255.255.252
no shutdown
exit

ip route 192.168.1.0 255.255.255.0 10.0.0.5

Configure Telnet on R3

line vty 0 4
password cisco
login
transport input telnet
exit

enable password class

Save configuration:

copy running-config startup-config

---

Step 5: Verify Connectivity

From R1:

ping 10.0.0.2
ping 10.0.0.6
ping 192.168.3.1

---

Step 6: Test Telnet

From R1 to R2:

telnet 10.0.0.2

Password:

cisco

From R1 to R3:

telnet 10.0.0.6

---

Step 7: Verify Telnet Users

show users

or

show line

---

Optional: Secure Telnet with Username and Password

Instead of only password authentication:

username admin password admin123

line vty 0 4
login local
transport input telnet

Then login with:

• Username: admin

• Password: admin123

---

Useful Verification Commands

show ip interface brief
show running-config
show ip route
show controllers serial 0/0/0

---

Important Notes

• Apply clock rate 64000 only on DCE serial interface.

• Use no shutdown on every active interface.

• Telnet requires reachable IP connectivity between routers.

• For better security, modern networks use SSH instead of Telnet.

SSH Alternative

Cisco IOS supports SSH, which encrypts remote access traffic and is more secure than Telnet.

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