Ports on an IOS device

Cisco uses the term interface to refer to physical ports on an IOS device. Interfaces can be configured with different settings, depending on the type of the interface and whether you are configuring an interface on a router or on a switch. For example, the Cisco 7201 Router has four GE physical ports (image source: […]

Run privileged commands within global config mode

Beginning with the IOS 12.3, the privileged-exec mode commands (such as show running-configuration, show interface status, etc.) can be executed within the global configuration mode and its submodes. This allows you to execute privileged-exec mode commands without needing to exit the current configuration mode. Here is an example that explains the usefulness of this feature:In […]

Configure descriptions

Adding a description to an interface on a Cisco device doesn’t provide any extra functionality, but it is useful for administrative purposes, since it will help you to remember the interface function. A description of an interface is locally significant and can be up to 240 characters long. It can be set using the description command from […]

show command

We’ve already mentioned a couple of show commands in the previous sections, so you should already we somewhat aware of this command. This command is used to display the device’s configuration, statistics, command history, interface status… The show command is invoked from the enable mode and can accept a lot of parameters:Floor1#show ? aaa Show AAA […]

IOS basic commands

In this article we will go through some basic IOS commands.Hostname commandThe hostname command is used to configure the device hostname. Because this command changes a device configuration, it must be entered in the global configuration mode. After typing the command, the prompt will change and display the new hostname.Here is an example that shows […]

Running & startup configuration

CIsco devices store commands in two configuration files:startup configurationrunning configuration Immediately after you type a command in the global configuration mode, it will be stored in the running configuration. A running configuration resides in a device’s RAM, so if a device loses power, all configured commands will be lost.To avoid this scenario, you need to copy […]

Get help in IOS

You can use the question mark to display a list of commands available in the prompt you are in:If the output spans more than one page, press the spacebar to display the following page of commands, or press Enter to go one command at a time. To quit the output, press q.To display only commands […]

IOS command modes

We’ve already learned that IOS has three main command modes: the user exec, privileged exec, and the global configuration modes. Each of these modes serves a different purpose and has its own set of commands. In this lesson we will describe each of this modes in more detail.User EXEC mode commandsInitially, a user logs into […]

Power on a Cisco device

When you first power-on a newly purchashed Cisco device, it will perform a power-on self-test (POST) to discover the hardware components and verify that all components work properly. If the POST is successful, the device will enter the setup mode. This mode presents a step-by-step dialog to help you configure some basic parameters, such as […]

Cisco IOS overview

IOS (Internetwork Operating System) is a multitasking operating system used on most Cisco routers and switches. IOS has a command-line interface with the predetermined number of multiple-word commands. This operating system is used to configure routing, switching, internetworking and other features supported by a Cisco device.NOTE Previous versions of Cisco switches ran CatOS, a discounted […]

Backing up IOS configuration

It is always a good idea to have a backup copy of the configuration of your IOS device. IOS configurations are usually copied to a TFTP server using the copy command. You can backup both the startup configuration and the running configuration of your device. The copy commands accepts two parameters: the first parameter is the […]

IOS boot sequence

The IOS boot sequence is a process performed after an Cisco IOS device is powered on. The IOS device performs a power-on self-test (POST) to test its hardware components and choose an IOS image to load. The boot sequence consists of the following steps:1. The device performs the power-on self-test (POST) process to discover and verify […]

Pipe character in IOS

IOS supports the use of the pipe character (represented with the | character) to filter the output of the show and more commands. The pipe function takes the output of the command and sends it to another function, such as begin or include. This way, you can filter the output to find the section of the output […]