How to show hidden default Cisco IOS configurations


Where did my “switchport access vlan 1” command go?

Have you ever noticed that Cisco has loaded default configurations onto the switch without showing it on your startup or running config? “switchport access vlan 1” is a good example.

Take a look at a default interface configuration on an IOS switch for instance shown by issuing the “show running-config

!
interface FastEthernet0/10
!

Compare that by running the “show running-config all” command and you’ll notice Cisco hides a bunch of hidden default configurations:

interface FastEthernet0/10
 switchport
 switchport access vlan 1
 switchport trunk encapsulation negotiate
 no switchport nonegotiate
 no switchport protected
 no switchport block multicast
 no switchport block unicast
 no ip arp inspection trust
 ip arp inspection limit rate 15 burst interval 1
 ip arp inspection limit rate 15
 no shutdown
 power inline consumption 15400
 power inline auto max 15400
 mls qos cos 0
 mls qos dscp-mutation Default DSCP Mutation Map
 snmp trap mac-notification change added
 snmp trap mac-notification change removed
 snmp trap link-status
 cdp tlv location
 cdp tlv server-location 
 cdp tlv app
 spanning-tree port-priority 3
 spanning-tree cost 3
 ip igmp snooping tcn flood
!

The output I have is from a Cisco 3560 PoE switch, so there will be varying defaults depending on the device you are issuing the command from.

My command is missing from my running/startup config?

By default Cisco hides a whole bunch of configs and it’s not just limited to the interface configurations. Often times you may enter a configuration and it may not show up on your running or startup config because it’s usually a default setting on your device. So next when you put in “no server pad” don’t panic when you don’t see it when you do not see it on your running config, just do a “show running-config all” to display those hidden defaults!

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About the Author

Alfred Tong
Author and owner of this blog. A Networking enthusiast, full time networking and systems Engineer. Generally curious about all things IT.Certifications: GIAC GSEC, CCNP-S, CCNP, CCSP, CCDP, CCNA, RHCE, JNCIA - FWV