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Chapter 1.2 Classify Network Protrocols and Communication - Coggle Diagram
Chapter 1.2 Classify Network Protrocols and Communication
1.2.1 Explain the purpose of the Cisco IOS
Cisco calls its operating system the Cisco
Internetwork Operating System
or Cisco
IOS
.
It is the embedded software architecture in all of the Cisco routers and is also the operating system of the Catalyst switches.
The Cisco IOS provides the following network services:
Basic routing and switching functions
Reliable and secure access to networked resources
Network scalability
Cisco IOS: Operating System
All electronic devices require an operating system.
Windows, Mac, and Linux for PCs and laptops
Apple iOS and Android for smart phones and tablets
Cisco IOS for network devices (e.g., switches, routers, wireless AP, firewall, …).
OS Shell
The OS shell is either a command-line interface (CLI) or a graphical user interface (GUI) and enables a user to interface with applications.
OS Kernel
The OS kernel communicates directly with the hardware and manages how hardware resources are used to meet software requirements
Hardware
The physical part of a computer including underlying electronics
Purpose of OS
Using a GUI enables a user to:
Use a mouse to make selections and run programs
Enter text and text-based commands
Using a CLI on a Cisco IOS 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
There are many distinct variations of Cisco IOS:
IOS for switches, routers, and other Cisco networking devices
IOS numbered versions for a given Cisco networking devices
Purpose of OS (Cont.)
All devices come with a default IOS and feature set and it is possible to upgrade the IOS version or feature set.
An IOS can be downloaded from cisco.com. However, a Cisco Connection Online (CCO) account is required.
Router user interface
A
dialup
connection using a modem or null modem connected to the router AUX port.
Telnet
to the router.
A
console
uses a low speed serial connection directly from a computer or terminal to the console connection on the router.
Explain how to access a Cisco IOS device for configuration purposes
Cisco IOS: Access Access Methods
Secure Shell (SSH)
Inband method for remotely and securely establishing a CLI session over a network.
User authentication, passwords, and commands sent over the network are encrypted.
As a best practice, use SSH instead of Telnet whenever possible.
Telnet
Inband interfaces remotely establishing a CLI session through a virtual interface, over a network.
User authentication, passwords, and commands are sent over the network in plaintext.
Console port
Out-of-band serial port used primarily for management purposes such as the initial configuration of the router.
Terminal Emulation Program
Regardless of access method, a terminal emulation program will be required.
Popular terminal emulation programs include PuTTY, Tera Term, SecureCRT, and OS X Terminal
Navigate the IOS: Cisco IOS Modes of Operation
The Cisco IOS modes use a hierarchical command structure
Each mode has a distinctive prompt and is used to accomplish particular tasks with a specific set of commands that are available only to that mode.
IOS Modes
: Privileged EXEC Mode (enable mode)
The privileged EXEC mode accesses all router commands.
This mode can be configured to require a password from the user before accessing it.
Configuration and management commands require that the network administrator be at the privileged EXEC level.
Global configuration mode and all other more specific configuration modes can only be reached from the privileged EXEC mode.
The privileged EXEC mode can be identified by the "#" prompt.
IOS Modes
: Global Configuration Mode
This mode allows users to modify the running system configuration.
To enter configuration mode, enter the command configure terminal from privileged mode.
Configuration mode has various submodes, starting with global configuration mode, which can be identified by the (config)# prompt following the router name.
Global Configuration mode (Cont)
As the configuration mode submodes change depending on what is being configured, the words inside the parentheses change.
For example, when you enter interface configuration submode, the prompt changes to (config-if)# following the router name.
To exit configuration mode, the user can enter end or press Ctrl-Z.
IOS Modes
: User EXEC Mode
The user EXEC mode allows only a limited number of basic
monitoring commands.
This is often referred to as a “view only” mode.
The user EXEC level does not allow any commands that might change the configuration of the router.
The user EXEC mode can be identified by the “>" prompt
1.2.3 Describe the command structure of the Cisco IOS software.
Basic IOS Command Structure
A Cisco IOS device supports many commands.
Each IOS command has a specific format or syntax and can only be executed in the appropriate mode.
The general syntax for a command is the command followed by any appropriate keywords and arguments.
Keyword
: a specific parameter defined in the operating system (in the figure, ip protocols)
Argument
: not predefined; a value or variable defined by the user (in the figure, 192.168.10.5)
After entering each complete command, including any keywords and arguments, press the Enter key to submit the command to the command interpreter.
The Command Structure
IOS Command Syntax
To determine the keywords and arguments required for a command, refer to the command syntax
Refer to the following table when looking at command syntax.
Examples:
description string
- The command is used to add a description to an interface. The string argument is text entered by the administrator such as description Connects to the main headquarter office switch.
ping ip-address
- The command is ping and the user-defined argument is the ip-address of the destination device such as in ping 10.10.10.5
IOS Help Features
IOS Context-Sensitive Help:
Context-sensitive help provides a list of commands and the arguments associated with those commands
To access context-sensitive help, enter a question mark ?, at any prompt.
IOS Help Features (Cont.)
IOS Command Syntax Check:
The command line interpreter checks an entered command from left to right to determine what action is being requested.
If the interpreter understands the command, the requested action is executed and the CLI returns to the appropriate prompt.
If the interpreter discovers an error, the IOS generally provides feedback such as “Ambiguous command”, “Incomplete command”, or “Incorrect command”.
Hot Keys and Shortcuts
Commands and keywords can be shortened to the minimum number of characters that identify a unique selection.
For example, the configure command can be shortened to conf because configure is the only command that begins with conf.
An even shorter version of con will not work because more than one command begins with con.
Keywords can also be shortened.
The IOS CLI support the following hotkeys:
Down Arrow
– Allows the user to scroll through command history
Up Arrow
- Allows the user to scroll backward through commands.
Tab
- Completes the remainder of a partially entered command.
Ctrl-A
- Moves to the beginning of the line.
Ctrl-E
– Moves to the end of the line.
Ctrl-R
– Redisplays a line.
Ctrl-Z
– Exits the configuration mode and returns to user EXEC.
Ctrl-C
– Exits the configuration mode or aborts the current command
Ctrl-Shift-6
– Allows the user to interrupt an IOS process (e.g., ping).
Cisco IOS command-line interface (CLI)
Cisco CLI is the primary user interface used for configuring, monitoring, and maintaining Cisco devices.
This user interface allows you to directly and simply execute Cisco IOS commands, whether using a router console or terminal, or using remote access methods.
Configuration Example:
Router # show running-config
Router (config)# hostname ‘name’
Router (config)# banner motd # ‘banner’ #
Router # copy running-config startup-config
Router (config-if)# ip address 192.168.1.1
Router (config)# interface vlan 20
Router (config) # enable secret class
Router (Config)# interface fa0/1
Primary Command Modes
Navigate the IOS: Configuration Command Modes
The primary configuration mode is called global configuration or simply, global config.
Use the configure terminal command to access.
Changes made affect the operation of the device.
Specific sub configuration modes can be accessed from global configuration mode.
Each of these modes allows the configuration of a particular part or function of the IOS device.
Interface mode
: to configure one of the network interfaces.
Line mode
: to configure the console, AUX, Telnet, or SSH access.
Navigate the IOS: Navigate Between IOS Modes
Navigate Between IOS Modes (Cont.)
The following provides an example of navigating between IOS modes:
Enter privileged EXEC mode using the enable command.
Enter global config mode using the configure terminal command.
Enter interface sub-config mode using the interface fa0/1 command.
Exit out of each mode using the exit command.
The remainder of the configuration illustrates how you can exit a sub-config mode and return to privileged EXEC mode using either the end or ^Z key combination.
Various commands are used to move in and out of command prompts:
To move from user EXEC mode to privileged EXEC mode, use the enable command.
Use return to user EXEC mode, use the disable command.
Various methods can be used to exit / quit configuration modes:
exit - Used to move from a specific mode to the previous more general mode, such as from interface mode to global config.
end - Can be used to exit out of global configuration mode regardless of which configuration mode you are in.
^z - Works the same as end.
1.2.4 Explain how devices communicate across network media
Overview of Network Components
Overview of Network Components (cont.)
End Devices
Intermediary Network Devices
Network Media
Network Representations
Topology Diagrams
:
Topology Diagrams (Cont.)
Network Representations (Cont.)
