Assigning IP Addresses to Interfaces

Objective:

To configure and assign IP addresses to router and PC interfaces in GNS3 using Cisco CLI.

Scenario Overview

• Network Name: Assigning IP addresses to interfaces

• Devices Required:

  • 2 Cisco Routers (e.g., Cisco 7200)

  • 2 PCs (Using Virtual PCs in GNS3 or VPCS)

  • 2 Switches (Optional)

• IP Addressing Scheme:

  • Network A: 192.168.1.0/24 (Between R1 and PC1)

  • Network B: 192.168.2.0/24 (Between R2 and PC2)

  • Network C: 10.0.0.0/30 (Link between R1 and R2)

Step 1: Setting Up the Topology

1. Open GNS3 and create a new project.

2. Drag and drop the following devices:

   • Two Routers (R1 and R2)

   • Two Virtual PCs (PC1 and PC2)

   • Two Switches (Optional)

3. Connect the devices as follows:

   • R1 (fa0/0) ↔ Switch1 ↔ PC1

   • R2 (fa0/0) ↔ Switch2 ↔ PC2

   • R1 (G2/0) ↔ R2 (G2/0) (Point-to-Point Link)

Topology

Step 2: Assigning IP Addresses to Router Interfaces

Router 1 (R1) Configuration

• Open the CLI for R1 and enter privileged EXEC mode:

R1#configure terminal
R1(config)#

• Assign IP address to fastEthernet 0/0 (Connected to PC1):

R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 192.168.1.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit

• Assign IP address to GigabitEthernet 2/0 (Connected to R2):

R1(config)#interface gigabitEthernet 2/0
R1(config-if)#ip add 10.0.0.1 255.255.255.252
R1(config-if)#no shutdown
R1(config-if)#exit

• Save the configuration:

R1#write memory
Warning: Attempting to overwrite an NVRAM configuration previously written
by a different version of the system image.
Overwrite the previous NVRAM configuration?[confirm]
Building configuration...
[OK]
R1#

Router 2 (R2) Configuration

• Open the CLI for R2 and enter privileged EXEC mode:

R2#configure terminal
R2(config)#

• Assign IP address to fastEthernet 0/0 (Connected to PC2):

R2(config)#interface fastEthernet 0/0
R2(config-if)#ip address 192.168.2.1 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#exit
R2(config)#

• Assign IP address to GigabitEthernet 2/0 (Connected to R1):

  bashCopyEdit

R2(config)#interface gigabitEthernet 2/0
R2(config-if)#ip address 10.0.0.2 255.255.255.252
R2(config-if)#no shutdown
R2(config-if)#exit
R2(config)#

• Save the configuration:

R2#write memory
Warning: Attempting to overwrite an NVRAM configuration previously written
by a different version of the system image.
Overwrite the previous NVRAM configuration?[confirm]
Building configuration...
[OK]
R2#

Step 3: Assigning IP Addresses to PCs

PC1 (192.168.1.2)

• Open PC1 (VPCS) CLI and set its IP address:

PC1> ip 192.168.1.100/24 192.168.1.1
Checking for duplicate address...
PC1 : 192.168.1.100 255.255.255.0 gateway 192.168.1.1

PC1> show ip

NAME        : PC1[1]
IP/MASK     : 192.168.1.100/24
GATEWAY     : 192.168.1.1
DNS         :
MAC         : 00:50:79:66:68:00
LPORT       : 20018
RHOST:PORT  : 127.0.0.1:20019
MTU         : 1500

PC1> save
Saving startup configuration to startup.vpc
.  done

PC1>

PC2 (192.168.2.2)

• Open PC2 (VPCS) CLI and set its IP address:

PC2> ip 192.168.2.100/24 192.168.2.1
Checking for duplicate address...
PC2 : 192.168.2.100 255.255.255.0 gateway 192.168.2.1

PC2> show ip

NAME        : PC2[1]
IP/MASK     : 192.168.2.100/24
GATEWAY     : 192.168.2.1
DNS         :
MAC         : 00:50:79:66:68:01
LPORT       : 20020
RHOST:PORT  : 127.0.0.1:20021
MTU         : 1500

PC2> save
Saving startup configuration to startup.vpc
.  done

PC2>

Step 4: Testing Connectivity

1. Test PC to Router Connectivity

• From PC1, ping R1:

PC1> ping 192.168.1.1

84 bytes from 192.168.1.1 icmp_seq=1 ttl=255 time=90.594 ms
84 bytes from 192.168.1.1 icmp_seq=2 ttl=255 time=11.411 ms
84 bytes from 192.168.1.1 icmp_seq=3 ttl=255 time=5.201 ms
84 bytes from 192.168.1.1 icmp_seq=4 ttl=255 time=2.508 ms
^C
PC1>

• From PC2, ping R2:

PC2> ping 192.168.2.1

84 bytes from 192.168.2.1 icmp_seq=1 ttl=255 time=40.780 ms
84 bytes from 192.168.2.1 icmp_seq=2 ttl=255 time=4.590 ms
84 bytes from 192.168.2.1 icmp_seq=3 ttl=255 time=4.257 ms
84 bytes from 192.168.2.1 icmp_seq=4 ttl=255 time=4.844 ms
^C
PC2>

2. Test Router-to-Router Connectivity

• From R1, ping R2:

R1#ping 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/15/20 ms
R1#

• From R2, ping R1:

R2#ping 10.0.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/16/20 ms
R2#

Step 5: Enable Routing (Optional)

If you want PC1 to communicate with PC2, you need to configure static routing or a dynamic routing protocol (RIP, OSPF, or EIGRP).

Static Route Configuration (On R1)

R1(config)#ip route 192.168.2.0 255.255.255.0 10.0.0.2

Static Route Configuration (On R2)

R2(config)#ip route 192.168.1.0 255.255.255.0 10.0.0.1

Now PC1 can ping PC2 and vice versa.

PC1> ping 192.168.2.100

84 bytes from 192.168.2.100 icmp_seq=1 ttl=62 time=49.785 ms
84 bytes from 192.168.2.100 icmp_seq=2 ttl=62 time=41.745 ms
84 bytes from 192.168.2.100 icmp_seq=3 ttl=62 time=23.887 ms
84 bytes from 192.168.2.100 icmp_seq=4 ttl=62 time=32.575 ms
^C
PC1>

Keywords

GNS3, CCNA, IP Addressing, Cisco Router, Interface Configuration, Subnetting, Routing, Static Route, Dynamic Routing, Ping Test, VPCS (Virtual PC Simulator), Switching, Network Topology, Point-to-Point Link, Gateway Configuration, Packet Forwarding, Connectivity Testing, OSPF Configuration, EIGRP Configuration, Troubleshooting Networks, سیسکو , آموزش سیسکو