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TOPIC 1.2 CLASSIFY NETWORK PROTOCOLS AND COMMUNICATION - Coggle Diagram
TOPIC 1.2 CLASSIFY NETWORK PROTOCOLS AND COMMUNICATION
1.2.2 Explain the purpose of the Cisco IOS
:pencil2: Cisco calls its operating system the Cisco Internetwork Operating System or Cisco IOS
:pencil2: It is the embedded software architecture in all of the Cisco routers and id 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 scability
OPERATING SYSTEM
All electronic devices require an operating system
:pushpin: Windows || Mac || Linux for PCs and laptops
:pushpin: Apple iOS and Android for smart phones and tablets
:pushpin: Cisco IOS for network devices >> 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 communcates directly with the hardware and manages how hardware resources are used to meet software requirements
HARDWARE
The physical part of a computer including underlying eletronics
ROUTER USER INTERFACE
The Cisco IOS software uses a command-line interface (CLI) as the traditional console environment
This environment is accesible through several methods;
:star: A
console
uses a low speed serial connection directly from a computer or terminal to the console connection on the router
:star: A
dialup
connection using a modem or null modem connected to the router AUX port
:star:
Telnet
to the router
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
:paperclip: All devices come with a default IOS and feature set. It is possible to upgrade the IOS version or feature set
:paperclip: An IOS can be downloaded from
cisco.com
. However, a Cisco Connection Online [ CCO ] account is required
1.2.2 HOW TO ACCESS A CISCO IOS DEVICE FOR CONFIGURATION PURPOSES
Access Methods
The three most common ways to access the IOS are;
Console port
Our of band serial port used primarily for management purposes such as the initial configuration of the router
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
Terminal Emulation Program
Regardless of access method, a terminal emulation program will be required.
Popular terminal emulation programs include;
:round_pushpin: PuTTY
:round_pushpin: Tera
:round_pushpin: Term
:round_pushpin:SecureCRT
:round_pushpin: 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
1] 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 ay commands that might change the configuration of the router
-The user EXEC mode can be identified by the ">" prompt
2] Privileged EXEC 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
A user interface to a router or switch utilizes an ASCII terminal program. The most commonly used version is the Windows HyperTerminal program
3] 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.
As the configuration mode submodes change depending on what is being configured, the wordsinside 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
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
1.2.3 THE COMMAND STRUCTURE OF THE CISCO IOS SOFTWARE
User EXEC mode
Privileged EXEC mode
Global configuration mode
Specific configuration modes
Cisco CLI
The Cisco IOS command-line interface (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 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) # enable secret class
Router (config)# interface vlan 20
Router (Config)# interface fa0/1
Navigate the IOS
Configuration Command Modes
:star: 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 between IOS Modes
:star: 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
:star: 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
:star: 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
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 STUCTURE
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;
:round_pushpin:
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
:round_pushpin:
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 Command Syntax Check
:check: The command line interpreter checks an entered command from left to right
to determine what action is being requested
:check: If the interpreter understands the command, the requested action is
executed and the CLI returns to the appropriate prompt
:check: If the interpreter discovers an error, the IOS generally provides feedback such as
“Ambiguous command”
,
“Incomplete command”
, or
“Incorrect command”
IOS Help Features
IOS Context - Sensitive Help;
Context-sensitive help provides a list of commands and the arguments associated with those commands within the context of the current mode
To access context-sensitive help, enter a question mark ?, at any
prompt
Hot Keys and Shortcuts
:clipboard: Commands and keywords can be shortened to the minimum number of
characters that identify a unique selection
:clipboard: 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;
:pushpin:
Down Arrow
>> Allows the user to scroll through command history
:pushpin:
Up Arrow
>> Allows the user to scroll backward through commands
:pushpin:
Tab
>> Completes the remainder of a partially entered command
:pushpin:
Ctrl-A
>> Moves to the beginning of the line
:pushpin:
Ctrl-E
>> Moves to the end of the line
:pushpin:
Ctrl-R
>> Redisplays a line
:pushpin:
Ctrl-Z
>> Exits the configuration mode and returns to user EXEC
:pushpin:
Ctrl-C
>> Exits the configuration mode or aborts the current command
:pushpin:
Ctrl-Shift-6
>> Allows the user to interrupt an IOS process --ping
1.2.4 HOW DEVICES COMMUNICATE ACROSS NETWORK MEDIA
Overview of Network Components
End Devices
Intermediary Network Devices
Intermediary network devices perform some or all of these functions;
Renegerate and transmit data signals
Mantain information about what pathways exist through network and internetwoek
Notify other devices of errors and communication failures
Direct data along alternate pathways when there is a link failure
Classify and direct messages according to priorities
Permit or deny the flow of data, based on security settings
Network Media
What is the maximum distance that the media can succesfully carry a signal?
Into what type of environment will the media be installed?
What is the amount of data and the speed at which it must be transmitted?
What is the cost of the media and installation?
Network Representations
Network Interface Card
Topology Diagrams
Phyical Topology
Logical Topology
