What is Cisco IOS ? Features how to Access a Cisco Router

What is Cisco IOS ? Features how to Access a Cisco Router?

This article is an introduction to the operating system of Cisco devices. What is Cisco IOS ? Features & how to download? All network devices and terminal require an operating system (OS). Cisco OS has three parts:

1. Shell , which is the part that interacts with the applications and the user.
2. Kernel, which is part of the OS that communicates with the PC hardware.
3. Hardware , which is the physical part of the computer.

WHAT IS CISCO IOS?

Cisco IOS is a set of network operating systems used in Cisco devices, which allows users to interact with those devices. All Cisco network devices come with a default IOS and it is possible to change the version or feature set of the IOS. We as users can interact with the shell through the command line interface (CLI) or the graphical user interface (GUI). While the CLI is a text-based environment, a GUI, such as Windows, SO X, Apple IOS or Android, allows the user to interact with the system in an environment that uses graphic icons, menus and windows.

Cisco IOS allows a network engineer to run CLI-based network programs and to enter text-based commands to configure these Cisco IOS.

The switch or router IOS provides options for the following:

• Configure interfaces on devices
• Enable routing and switching functions
• Configuration of different protocol on Cisco devices

The Cisco IOS is stored in flash memory, this means the following:

• It is a non-volatile storage: the information is not lost when the power is cut.
• It can be modified or overwritten as necessary.
• It can be used to store several versions of IOS.
• The IOS is copied from flash memory to volatile RAM.
• The amount of flash memory and RAM determines which IOS can be used.

What are Cisco IOS FUNCTIONS?

The main functions that Cisco routers and switches perform or enable include the following: 

1. Security
2. Routing
3. QoS
4. Addressing
5. Resource Management and Interface

How to Access a Cisco Router?

As I mentioned above you can interact with the OS shell. There are several ways to access the CLI environment and configure the device. The most common methods are as follows:

• Console
• Assistant
• Virtual terminal (Telnet / SSH)

Access Cisco Router through CONSOLE PORT

• The device can be accessed even if there are no network services configured (out of band).
• Form used for initial device configuration .
• You need a special console cable .
• Allows configuration commands to be entered.
• It must be configured with passwords to prevent unauthorized access.
• The device must be located in a secure room so that the console port cannot be easily accessed.

How to Access Cisco Router through AUXILIARY PORT

• Out of band connection.
• Use the telephone line .
• It can be used as a console port.
• Cisco catalytic switch does not have an auxiliary port .

VIRTUAL TERMINAL

There are two ways, through Telnet or by Secure Shell (SSH)

• Telnet
• Method to access the CLI remotely through a network.
• Requires active network services and that there is an active interface configured.

• Secure Shell (SSH)
• Remote login similar to Telnet, but uses more security .
• It has more secure password authentication.
• Use encryption when transporting data.

TERMINAL EMULATION PROGRAMS

To connect to a network device using the aforementioned access methods, there are a variety of programs such as:

• PuTTY
• SecureCRT
• HyperTerminal 
• Tera Term 
• OS X Terminal

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