For Ethernet interface configuration you need to make a physical connection to the router Ethernet Interface. After establishing a connection, you can proceed with the basic configuration of Ethernet, Fast Ethernet, or Gigabit Ethernet interfaces.
Connecting To Your Router
After connecting to a router you need to get into the Global Configuration Mode of your router using the following commands:
Enter configuration commands, one per line. End with CNTL/Z.
The next option is to choose the correct interface. There are many different types of interfaces available on Cisco routers such as Ethernet, Fast Ethernet, Gigabit Ethernet or serial interface. All devices in current IOS versions are numbered for example.
- Gigabit Ethernet interfaces– GigabitEthernet 0/0 (G0/0) , GigabitEthernet 0/1 (G0/1)
- A serial WAN interface card (WIC) interfaces– Serial 0/0/0 (S0/0/0) and Serial 0/0/1 (S0/0/1)
For example, we want to configure FastEthernt 0/0 interface. We should enter the interface mode of FastEthernet 0/0 using the following command.
|Router(config)#interface FastEthernet 0/0|
Adding A Description To Ethernet Interface
This feature in not necessary, you may bypass this feature. This feature providing a description about the interface and it does not assist with the configuration. It just helps prevent human error.
|Router(config-if)#description Internal Interface|
Setting IP Address To Interface
Now you did all prerequisites before adding IP address. Now you can add IP address to this interface.
|Router(config-if)#ip address 192.168.1.1 255.255.255.0|
Enabling Your Interface
Before using the router interface you need to enable the router interface. You can enable the router interface by entering the following command.
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
Verifying Router Interface Configuration
There are several commands that can verify interface configuration. The show IP interface brief is the most useful command for verifying interface configuration. The output of this command display all interfaces with their IPv4 address, and their current status. The configured and connected interfaces should display a Status “up” and Protocol “up”. Any other statements would indicate a problem with either the configuration or the cabling. Remember that show command are working in “Privileged mode”
You can also verify the configuration of interface from “show running-config”. and Show startup-config.Another way to verify connectivity from the interface using the ping command. Ping command send five consecutive pings and measure minimal, average, and maximum round-trip times.Exclamation marks verify connectivity.
Following is the output of the show IP interface brief command, which show all three interfaces of the router. FastEthernet 0/0, status is up and protocol is up. its mean that this interface is connected to other network and protocol is up. FastEthernet status is up, it means that interface is configured and enabled with no shutdown command, its protocol is down, its mean that there is something wrong with the cable or some problem from another side. Serial 0/0/0 interface is not configured, not enabled and there is no IP address assigned to this interface.
Router#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.0.1 YES manual up down
FastEthernet0/1 192.168.1.1 YES manual up up
Serial0/0/0 unassigned YES unset administratively down down
Following are other commands that we can use to verify interface configuration.
- show interfaces– This command displays statistics for all interfaces on the device.
- Ping – This command generated five exclamation marks verifying connectivity to the remote side.
- show IP interface brief– Displays the IPv4 statistics for all interfaces on a router.
- Show running-config-.This command display entire configuration of the router. Here we need to see the router section in the configuration file to verify the interface configuration.
- Show startup-config:- When the configuration is saved with the write command, then configuration can be verified by the help of this command.