Ch2 Configure A Network Operating System - John Flashcards
network operating system.
A network operating system enables device hardware to function and provides an interface for users to interact.
Cisco Internetwork Operating System (IOS)
is a generic term for the collection of network operating systems used by Cisco networking devices. Cisco IOS is used for most Cisco devices, regardless of the type or size.
Operating System
All end devices and network devices require an operating system (OS).
kernel.
the portion of the OS that interacts directly with computer hardware is known as the kernel.
Communicates between the hardware and software of a computer and manages how hardware resources are used to meet software requirements.
shell
The portion that interfaces with applications and the user is known as the shell.
The user can interact with the shell using a command-line interface (CLI) or a graphical user interface (GUI).
The User interface that allows users to request specific tasks from the computer. These requests can be made either through the CLI or GUI
command-line interface (CLI)
the user interacts directly with the system in a text-based environment by entering commands on the keyboard at a command prompt. The system executes the command, often providing textual output. The CLI requires very little overhead to operate. However, it does require that the user have knowledge of the underlying structure that controls the system.
A GUI interface
such as Windows, OS X, Apple iOS, or Android allows the user to interact with the system using an environment of graphical icons, menus, and windows
However, GUIs may not always be able to provide all of the features available at the CLI. GUIs can also fail, crash, or simply not operate as specified. For these reasons, network devices are typically accessed through a CLI. The CLI is less resource intensive and very stable when compared to a GUI.
Hardware
The physical part of a computer including underlying electronics.
Purpose of OS
A CLI-based network operating system like the Cisco IOS on a switch or router enables a network technician to:
• Use a keyboard to run CLI-based network programs
• Use a keyboard to enter text and text-based commands
• View output on a monitor
Cisco networking devices run particular versions of the Cisco IOS. The IOS version is dependent on the type of device being used and the required features. While all devices come with a default IOS and feature set, it is possible to upgrade the IOS version or feature set to obtain additional capabilities.
Access Methods
A Cisco IOS switch can be implemented with no configuration and still switch data between connected devices. By connecting two PCs to a switch, those PCs will instantly have connectivity with one another.
Even though a Cisco switch will function immediately, configuring initial settings are a recommended best practice. There are several ways to access the CLI environment and configure the device.
The most common methods are:
Console
Secure Shell(SSH)
Telnet
Console
This is a physical management port that provides out-of-band access to a Cisco device. Out-of-band access refers to access via a dedicated management channel that is used for device maintenance purposes only.
The advantage of using a console port is that the device is accessible even if no networking services have been configured, such as when performing an initial configuration of the networking device. When performing an initial configuration, a computer running terminal emulation software is connected to the console port of the device using a special cable. Configuration commands for setting up the switch or router can be entered on the connected computer.
Secure Shell (SSH)
SSH is a method for remotely establishing a secure CLI connection through a virtual interface, over a network. Unlike a console connection, SSH connections require active networking services on the device including an active interface configured with an address.
is the recommended method for remote management because it provides a secure connection SSH provides encrypted passwords authentication and transport of session data. This keeps the user ID, password, and the details of the management session private. Most versions of Cisco IOS include an SSH server and an SSH client that can be used to establish SSH sessions with other devices.
Telnet
Telnet is an insecure method of remotely establishing a CLI session through a virtual interface, over a network. Unlike SSH, Telnet does not provide a securely encrypted connection. User authentication, passwords, and commands are sent over the network in plaintext.
Best practice dictates to uses SSH instead of telnet for remote management CLI connections. Cisco IOS includes a Telnet server and a Telnet client that can be used to establish Telnet sessions with other devices.
auxiliary port
Some devices, such as routers, may also support a legacy auxiliary port that was used to establish a CLI session remotely using a modem. Similar to a console connection, the AUX port is out-of-band and does not require networking services to be configured or available.
Cisco IOS Modes of Operation
To initially configure a Cisco device, a console connection must be established. Once consoled in, the network technician will have to navigate through various command modes of the IOS CLI. The Cisco IOS modes use a hierarchical structure and are quite similar for both switches and routers.
To simulate the initial configuration of a Cisco switch, you first need the proper cable.
console cable. Then on the desktop PC, choose the RS 232 serial port, click on it, then drag over to the 2960 switch, click on the switch, and then choose the console port. I now have a connection from the desktop PC to the 2960 series switch using a rollover, or console cable.
terminal emulation program
Once you have the serial cable running from your desktop PC to the switch console port, you’l l need a terminal emulation program for the initial configuration of the Cisco switch. To do this, you click on the PC, click on the desktop tab. And these are your desktop applications. The terminal emulation program says “terminal.” If you click on it, you’ll see the terminal configurations that you would need if you were using a real terminal emulation program, like Putty or Tera Term.
You can see the bits per second, data bits, parity, stop bits, and flow control have already been configured for you. All you need to do is click “okay.” Now I have a terminal connection to the switch.
User EXEC Mode
This mode has limited capabilities but is useful for basic operations. It allows only a limited number of basic monitoring commands but does not allow the execution of any commands that might change the configuration of the device. The user EXEC mode is identified by the CLI prompt that ends with the > symbol.
Privileged EXEC Mode
o execute configuration commands, a network administrator must access privileged EXEC mode. Higher configuration modes, like global configuration mode, can only be reached from privileged EXEC mode. The privileged EXEC mode can be identified by the prompt ending with the # symbol. Enable press enter
Global Configuration Mode
To configure the device, the user must enter Global Configuration Mode, which is commonly called global config mode.
From global config mode, CLI configuration changes are made that affect the operation of the device as a whole. Global configuration mode is identified by a prompt that ends with (config)# after the device name, such as Switch(config)#. Enable (if not in privileged exec mode) then configure terminal
Global configuration mode is accessed before other specific configuration modes. From global config mode, the user can enter different sub-configuration modes. Each of these modes allows the configuration of a particular part or function of the IOS device. Two common sub-configuration modes include: configure terminal
Two common sub-configuration modes include:
Line Configuration Mode
Interface Configuration Mode
Line Configuration Mode
Used to configure console, SSH, Telnet, or AUX access.
the default prompt for line configuration mode is Switch(config-line)#
Interface Configuration Mode
Used to configure a switch port or router network interface.
the default prompt for interface configuration mode is Switch(config-if)#.
