This tutorial shows how to configure two routers, so they can communicate with each other. It covers the basic of configuring interfaces and checking the connectivity between them.

Let look at the following network diagram.

Router 1 connecting Router 2

The router R1 is connected through fast ethernet 0/0 to router R2′s fast ethernet 0/0. In order to have connectivity between them, the interface fa0/0 have to be configured with an IP address (same subnet) on both end. As they are directly connected to each other, no routing protocol is required.

Configuration

Configuring R1. We’ll be assigning IP address of 192.168.1.1 with 32bit mask.

R1>enable
R1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 192.168.1.1 255.255.255.252
R1(config-if)#no shutdown
R1(config-if)#
*Mar  1 00:02:44.399: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar  1 00:02:45.399: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

Configuring R2. R2 will have same configuration as R1, except for the IP address which will be 192.168.1.2

R2>enable
R2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#interface fastEthernet 0/0
R2(config-if)#ip address 192.168.1.2 255.255.255.252
R2(config-if)#no shutdown
R2(config-if)#
*Mar  1 00:02:44.399: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up
*Mar  1 00:02:45.399: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

Thats it for the configuration part. To check if the connectivity between them is working, use ping command.

Ping address 192.168.1.2 from R1 or 192.168.1.1 from R2 to check the connectivity.

R1#ping 192.168.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/57/72 ms
R1#

Seems like the R1 and R2 is configured properly.

Summary

This tutorial showed you how to connect two routers, and configuring them with proper IP address for basic connectivity.

Most of the commands used in this tutorial have been explained in last articles, so there should be no problem understanding it.

Check Basic Cisco IOS and Configuring Interface tutorials if you are having problems.

We have used Fast Ethernet to connect two routers. Configuration on other links should be fairly similar to Fast Ethernet.

Thats it for this tutorial. Enjoy