Are you aspiring to be highly proficient with Cisco IOS? Then, there are some important commands that you have to learn. In this blog post, we will share with you some of the ten essential commands that you need to understand when working through different troubleshooting and configuration tasks. They are as follows:
1. ‘show interface’
This command shows the status of interfaces of your router or access server. Some of the output offered by this command includes an interface status (up-down). It shows the statistics of hardware, address, MTU, ARP type, information about Input and Output queue, and errors. The ‘show interface’ command is crucial when it comes to troubleshooting a switch or a router.
2. ‘?’ Command
You are likely surprised to find this command in the list. You obviously understand that this is just a help command. Nonetheless, it is essential to know that Cisco IOS is quite different from other OS in terms of using ‘help’, also known as the question mark. This operating system is known to be of a command-line type that has thousands of parameters and commands associated with ‘?’.
There are different ways you can use this command. For instance, you can utilize it for the list of every possible command by typing ‘?’ at the system prompt. Additionally, you can also make use of it to know what is the next parameter should be. You may also use this command to see others that begin with a specific letter. For instance, you can type “show c?” and it will generate a list of commands that begin with the letter C.
3. ‘show running-config’
You can use this command to reveal the current configuration of a router, firewall, or switch. The ‘show running-config’ command has no keywords or arguments. It refers to the configuration that is stored in RAM. The following command can show the building configuration, version, hostname, and other information.
4. ‘copy running-config startup-config’
The ‘copy running-config startup-config’ command is designed to save the currently running configuration. The saving is done to the startup configuration file in NVRAM (also known as Non Volatile Random Access Memory). In case there is a power loss, Non Volatile RAM will preserve the configuration, which means if you edit something on the router’s configuration, you will not utilize this particular command and reboot a router, the changes will not be saved.
5. ‘show ip interface’
This command provides numerous functional information about the status and configuration of IP services and protocols. Thus, you can get details related to all the IP-related characteristics of an interface, including any secondary addresses that don’t show up by using ‘show interface’. You can also know the statistics about multicast groups, inbound access, Proxy ARP, and much more. It is essential to mention that this command as well as ‘show ip interface brief’ is more popular than ‘show interface’.
6. ‘no shutdown’
‘shutdown’ allows to disable an interface and all its functions while ‘no shutdown’ restarts all of it. Suffice to mention that the command should be utilized in the interface configuration mode, and can also be used for troubleshooting and new interfaces. There are also no arguments or keywords. On different interfaces, it can also cause the DTR signal to be dropped or the optical bypass switch.
7. Config Terminal, Interface, Router, and Enable Commands
There are different modes of Cisco routers that allow you to display or modify specific data. Your ability to move between these different modes is very important to the success of your router configuration. For instance, when you are logging in, ‘start off’ begins with the user mode, with the prompt looking like ‘>’. From this point, you will type ‘enable’ in order to move to the privilege mode, with the prompt ‘#’. When the system is in the privileged mode, everything can be shown, but it will be impossible to make changes. The next step is to type ‘config terminal’, alternatively, you can simply type ‘config t’. This will take you to the global configuration mode. From this stage, you can alter the global parameters. Now, to change a parameter on a specific interface, check the interface configuration mode that has the ‘interface’ command, for instance, with the prompt showing a router (config-if)#). From the global configuration mode, you may also go to the router configuration with the ‘router {protocol}’ command. You can simply type ‘exit’ to exit any mode.
8. Debug Command
This command has a wide variety of options, and it doesn’t work on its own. It offers comprehensive debugging output on a specific protocol, service, or application. For instance, ‘debug ip routing’ will show each time a route is removed from or added to the router. It is essential to mention that debugging can be quite precarious as its procedure has priority over the others. You should be ready to disable the feature with the ‘undebug all’ command or the ‘no debug’ command.
9.‘show version’
This command shows the configuration register of a router, such as the last time it was booted, the IOS file name, the amount of Flash and RAM in the router, the IOS version, and the router model. These are basically the firmware settings of the router designed for booting up.
10. ‘show ip route’
This command is used to indicate the current state of the routing table. It shows a list of each network that the router has the capacity to attain, its metrics, and how to attain it. You can also use ‘clear ip route’ to clear out the routing table for all routes. Use ‘clear ip route x.x.x’ to clear a single route. ‘x.x.x’ refers to the network you need to clear, for example, you can type ‘clear ip route 192.0.2.1’.
Conclusion
Of course, Cisco IOS has a lot of commands that you can use, but learning these ten is a good start to become a good IT professional. These important commands will definitely help you to succeed in your future profession.
