Configuring Cisco Routers: Telnet Access and Static IPs for IPv4/IPv6 in a Multi-Device Network

Configuring Cisco Routers: Telnet Access and Static IPs for IPv4/IPv6 in a Multi-Device Network
Step-by-Step Guide for 2 Routers, 2 Switches, and 2 PCs

Network Topology Overview
Devices:

• Routers: R1, R2 (connected via serial interface).

• Switches: SW1, SW2 (connected to R1 and R2, respectively).

• PCs: PC1 (connected to SW1), PC2 (connected to SW2).

Subnets:

• IPv4:

  • PC1: 192.168.1.0/24 | PC2: 192.168.2.0/24

  • Router Link: 10.0.0.0/30

• IPv6:

  • PC1: 2001:db8:1::/64 | PC2: 2001:db8:2::/64

  • Router Link: 2001:db8:ff::/64

Step 1: Configure Router Interfaces with Static IPv4 and IPv6

Router R1

enable  
configure terminal  
! Configure IPv4  
interface gigabitethernet0/0  
 ip address 192.168.1.1 255.255.255.0  
 no shutdown  
!  
interface serial0/0/0  
 ip address 10.0.0.1 255.255.255.252  
 no shutdown  
! Configure IPv6  
ipv6 unicast-routing  
interface gigabitethernet0/0  
 ipv6 address 2001:db8:1::1/64  
!  
interface serial0/0/0  
 ipv6 address 2001:db8:ff::1/64  
exit  

Router R2

configure terminal  
interface gigabitethernet0/0  
 ip address 192.168.2.1 255.255.255.0  
 no shutdown  
!  
interface serial0/0/0  
 ip address 10.0.0.2 255.255.255.252  
 no shutdown  
! IPv6 Configuration  
ipv6 unicast-routing  
interface gigabitethernet0/0  
 ipv6 address 2001:db8:2::1/64  
!  
interface serial0/0/0  
 ipv6 address 2001:db8:ff::2/64  
exit  

Step 2: Configure Static Routing

On R1

ip route 192.168.2.0 255.255.255.0 10.0.0.2  
ipv6 route 2001:db8:2::/64 2001:db8:ff::2  

On R2

ip route 192.168.1.0 255.255.255.0 10.0.0.1  
ipv6 route 2001:db8:1::/64 2001:db8:ff::1  

Step 3: Enable Telnet Access on Routers

Configure VTY Lines and Passwords

! On both R1 and R2  
configure terminal  
line vty 0 4  
 password cisco  
 login  
 transport input telnet  
exit  
!  
enable secret class  
username admin privilege 15 secret cisco123  

Step 4: Configure Switches (SW1 and SW2)

Basic VLAN and Management IP

! On SW1  
configure terminal  
interface vlan 1  
 ip address 192.168.1.2 255.255.255.0  
 ipv6 address 2001:db8:1::2/64  
 no shutdown  
exit  
!  
ip default-gateway 192.168.1.1  
ipv6 default-gateway 2001:db8:1::1  
! Enable Telnet  
line vty 0 15  
 password cisco  
 login  
 transport input telnet  

Repeat similar steps for SW2 with IPs 192.168.2.2 and 2001:db8:2::2.

Step 5: Assign Static IPs to PCs

PC1 Configuration

• IPv4: 192.168.1.10/24 | Gateway: 192.168.1.1

• IPv6: 2001:db8:1::10/64 | Gateway: 2001:db8:1::1

PC2 Configuration

• IPv4: 192.168.2.10/24 | Gateway: 192.168.2.1

• IPv6: 2001:db8:2::10/64 | Gateway: 2001:db8:2::1

Step 6: Verify Connectivity

Test Telnet from PC1 to R1

telnet 192.168.1.1  
! Enter password: cisco  

Check IPv6 Reachability

ping 2001:db8:2::10  # From PC1 to PC2  

View Routing Tables

show ip route  
show ipv6 route  

Troubleshooting Tips

1. Interfaces Down: Use show ip interface brief or show ipv6 interface brief.

2. Telnet Fails: Ensure passwords are correct and VTY lines are configured.

3. No IPv6 Connectivity: Verify ipv6 unicast-routing is enabled on routers.

Security Note

• Replace Telnet with SSH for encrypted communication (use transport input ssh and generate RSA keys).

• Use stronger passwords than "cisco" in production environments.

Conclusion
With static IPs, Telnet access, and dual-stack IPv4/IPv6 configurations, this setup ensures seamless communication across routers, switches, and PCs. Adjust IPs/subnets as needed for your network!

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