Reset Cisco IOS Configuration Specific Defaults

You may want to change the configuration for a specific interface, or other type of configuration resets the default Cisco IOS configuration used in the production. A great example would be you have configuration for interface FastEthernet0/0 and its about 10 rows on it and you want to clear the configuration on the interface, normally you would deny use of any command under the interface configuration before configuring all of the rows.

Quick and easy way to clear the configuration on an interface is to use the default command in global configuration, followed by the interface name and number. Configure this command to reset the interface is configured as the default "any IP address" and "off" and from there, you can apply the new configuration interface and save for a while not denying so many interfaces to configure the thread.

Lab Prerequisites:

• If you are using GNS3 than load the Stub Area Networking GNS3 topology and start R1.
• Establish a Console session with Router 1.

Lab Objectives:

Configuring interfaces FastEthernet0/0 and 10.1.1.254/24 IP address hard-coded into the full 100Mbps speed and duplex.

Reset interface on the FastEthernet0/0 using the default global configuration command configured earlier.

Lab Instruction:

Step 1. First target countries to simulate the configuration of an interface, you will need to 10.1.1.254/24 the IP address assigned to the interface FastEthernet0/0 and ass hard code speed and duplex to 100Mbps full duplex.

Router con0 is now available

Press RETURN to get started.

Router>enable

Router#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#int fa0/0

Router(config-if)#ip add 10.1.1.254 255.255.255.0

Router(config-if)#duplex full

Router(config-if)#speed 100

Router(config-if)#no shut

%LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed

state to up

Router(config-if)#

Router(config-if)#do show run int fa0/0

Building configuration...

Current configuration : 94 bytes

!

interface FastEthernet0/0

 ip address 10.1.1.254 255.255.255.0

 duplex full

 speed 100

end

Router(config-if)#

Step 2. Now Fa0/0 resets to the default configuration of the interface default command is executed from a number followed by the interface name and verify that the configured global configuration.

Router(config-if)#exit

Router(config)#default interface fa0/0

Building configuration...

Interface FastEthernet0/0 set to default configuration

Router(config)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down

%LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

Rrouter(config)#do show run interface FastEthernet 0/0

Building configuration...

Current configuration : 73 bytes

!

interface FastEthernet0/0

 no ip address

 duplex auto

 speed auto

end

Router(config)#