How do you verify and troubleshoot on a router? Please note that you need to be in privileged mode in order to do this. you have to you can type show running dash config to view the current running configuration of a router or you can either type show startup config to look at the startup configuration of a router remember you can use show configuration or you can use show run interface in this example this giga interface 0 0 to check configuration running on the specific interface you can also check the interface status you have to be in standard or privileged mode to do this and you can do that by simply typing show interface gig 0 0 this checks the interface off you get the net zero slash zero you can check the status of all interfaces on the router by simply typing show interface description and as you can see on the screen it will list all the interfaces that you have on the router with the status and the protocol and the description of those interfaces you can get a brief list of ipv4 status of all interfaces on a router by simply typing show ip interface brief if you want to get a brief list of ipv6 status of all interfaces you would have to type show ipv6 interface brief you can find out directly attach cisco devices by using cdp which is the cisco discovery protocol you have to be in standard or privileged mode to do this and you can do so by typing the command show cdp neighbor an essential tool to use when troubleshooting on a router is the ability to check the logs you can check the logs by simply typing the command show login in privilege mode remember that events occurring on the router are saved in the logs you can also show the software and hardware details of the device by simply typing show version or show hardware you can check the device status while inside of configuration mode as well you can do so by simply typing do show interface followed by the interface name in this case is gig g 0 0. the do command lets the operator run all privilege mode commands from within the configuration mode of the router this is much quicker and easier than exiting configuration mode running the status command and then returning to configuration mode how do you undo configuration of a cisco device to undo ios configuration you simply negate the configuration command as shown on the screen you have an interface with configuration fast ethernet 0 0 with a description link to core router and an ip address of with a subnet mask of if you would like to undo this configuration you would simply have to go into configuration mode by typing conf t going into the fast ethernet 0 0 and typing no ip address to remove the ip address configuration from the interface. You would then complete this by typing the "end" command which would take you back to privilege mode. Whenyou type the command "show run interface fa 0/0" you would see that the ip addresshas been removed from the configuration of the interface. This was done by simply typing "no ip address" to remove the ip address configuration.

© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.

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