Interface is full
This occurs most commonly when you are labbing or testing something and an interface ends up with a lot of configuration, possibly something like the following:
Router(config-if)#do sh run int fa0/0
Current configuration : 320 bytes
description Show the Default command
ip dhcp relay information trusted
ip address 198.18.56.1 255.255.255.0
no ip route-cache cef
no ip route-cache
ip ospf authentication-key MYOHMY
ip ospf network point-to-point
ip ospf hello-interval 20
standby 1 ip 198.18.54.90
You want to clear this configuration and reuse the interface for some other task. Normally you would need to issue a the “no” command for each line.
The ‘default’ command
The default command has many uses, and this is only one of them, but possibly it is the most useful.
Router(config-if)#default interface fa0/0
Interface FastEthernet0/0 set to default configuration
Router(config)#do sh run int fa0/0
Current configuration : 61 bytes
no ip address
That’s it. Simple and elegant.
Other posts in the series
- Cisco IOS CLI Regex: sh ip bgp in
- IOS CLI Tip: More accurate pipe commands
- Cisco Nexus NXOS and Fixing broken “switchto” syntax with alias
- show ip eigrp topology all
- Cisco IOS CLI Shortcuts
- The poor man's IOS Traffic Generator
- IOS: "terminal monitor" on, off - logging to your terminal
- IOS: Console, Terminal, Monitor, VTY - what is what ?
- IOS: Clearing an interface configuration (This post)
- IOS: Setting Terminal Window Length
- IOS CLI: show run linenum
- IOS: Setting the TCP timeout on IOS
- IOS: enable and .... disable ?
- IOS: Reverse SSH console access - Part 2
- IOS:Open Source Lab DNS and IP addressing
- IOS: Reverse SSH console access
- ip tcp timestamp
- Cisco ASA and IOS command tip - test aaa-server