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TOPIC 1.2 : CLASSIFY NETWORK PROTOCOLS AND COMMUNICATION - Coggle Diagram
TOPIC 1.2 : CLASSIFY NETWORK PROTOCOLS AND COMMUNICATION
1.2.1 Explain the purpose of the Cisco IOS.
1.2.2 Explain how to access a Cisco IOS device for configuration purposes.
1.2.3 Describe the command structure of the Cisco IOS software.
The Purpose of the CISCO IOS
Cisco calls its OS the Cisco Internetwork Operating System / Cisco IOS
is an embedded software architecture in all of the Cisco routers & the OS of the Catalyst switches
Cisco IOS provides network services such as :
Basic routing and switching function
Reliable and secure access to networked resources
Network scalability
Operating System
Cisco IOS is for network devices such as switches, routers, WAP, firewall
(refer to picture in slide 5)
OS Shell ( most outer shell)
it is either a command-line interface(CLI) or a graphical user interface(GUI) and enables a user to interface with applications
OS Kernel (second layer shell)
communicates directly with the hardware and manages how hardware resources are used to meet software requirements
Hardware (the most inner shell)
the physical part of a computer including underlying electronics
Router User Interface
Cisco IOS software uses a CLI as the traditional console environment
The environment is accessible through several methods :
A
console
uses a low speed serial connection directly from a computer or terminal to the console connection on the router
A
dialup
connection using a modem or null modem connected to the router AUX port
Telnet
to the router
Purpose of OS
Using a GUI enables a user to :
use a mouse to make selections and run programs
enter a 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
-3. Variations of Cisco IOS :
IOS for switches routers and other Cisco networking device
IOS numbered versions for a given networking device
all devices comes with a default IOS and feature set
it is possible to upgrade the IOS version or feature set
an IOS can be downloaded from cisco.com but its require a Cisco Connection Online (CCO) account
Access Methods
1. Console port
out-of-band serial port used primarily for management purposes such as the initial configuration of the router
2. Secure Shell (SSH)
in band method for remotely and securely establishing a CLI session over a network
user authentication, passwords and commands sent over the network are encrypted
Telnet
in band interfaces remotely establishing a CLI session through a virtual interface over a network
user authentication, passwords and commands are sent over the network in plain text
Terminal Emulation Program
a requirement
Example of popular terminal emulation programs :
PuTTY, Tera Term, SecureCRT, OS X Terminal (refer to slide 10 to see image of this program)
Cisco IOS Modes of Operation
Cisco IOS modes use a hierarchical command structure
each mode has a distinctive prompt an is used to accomplish particular tasks with a specific set of commands that are available only to that mode
IOS modes :
User EXEC Mode
Privileged EXEC Mode (enable mode)
Global Configuration Mode
User EXEC Mode
allows only a limited no. of basic monitoring commands
referred as "view only" mode
does not allow any commands that might change the configuration of the router
can be identified by the ">"prompt
Privileged EXEC Mode
can accesses all router commands
mode can be configured to require a password from the user before accessing it
configuration and management commands can be done by the network administrator only if they at this mode level
global configuration mode and all other more specific configuration modes can only be reached from this mode
can be identified by the "#" prompt
Global Configuration Mode
allows user to modify the running system configuration
to enter configuration mode, enter command "configure terminal" from privileged mode
in configuration mode has various submodes starting with global configuration mode which can be identified by the (config)# following the router name
the words inside the parentheses will change depends on submodes
e.g : when we enter interface configuration submode, the prompt change to (config-if)# following the router name
to exit configuration mode, user can enter
end
or press Ctrl-Z
Cisco CLI
the primary user interface used for configuring, monitoring and maintaining Cisco devices
allows user to directly and simply execute Cisco IOS commands, whether using a router console or terminal or remote access methods
Configuration Command Modes
the primary configuration mode is called
global configuration
or
global config
use configure terminal command to access
-2. changes made effect the operation of the device
specific sub configuration mode can be accessed from global config mode
-each of those sub configuration modes allows 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
to move from user EXEC mode to privileged EXEC mode, use
enable
command
to return to user EXEC mode, use
disable
command
exit
- to move from specific mode to the previous more general mode
end
- can be used to exit out of global config mode regardless which configuration mode user in
^z
- same as
end
IOS Help Features
1. IOS Context-Sensitive Help
helps to provide a list of commands and the arguments associated with those commands within the context of the current mode
to access, enter a question mark(?) at any prompt
2. IOS Command Syntax Check
checks an entered command line from left to right to deterine what action is being requested
if the interpreter understand 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
IOS Command Syntax
function to determine the keywords and arguments required for command
refer to table at slide notes 28
Hot Keys and Shortcuts
a shortened characters that identify a unique selection
e.g :
configure
command become
conf
bcs configure is the only command that begins with
conf
refer to slide notes 32 for a list of hotkeys that IOS CLI supports
Basic IOS Command Structure
each IOS command has a specific format or syntax and can be only executed in the appropriate mode
the general syntax for a command is
the command followed by any appropriate keywords and arguments
-
keywords
: a specific parameter defined in the OS
argument
: not predefined, a value or variable defined by the user
after completing entering command, press the
Enter
key to submit the command to the command interpreter
refer slide notes 27 for example
1.2.4 Explain how devices communicate across network media
Devices
Some example of devices that is an end devices in network are :
Desktop computer
IP Phone
Laptop
Printer
Wireless tablet
TelePresence Endpoint
Some example of devices that are work as intermediary network devices :
Wireless router
LAN Switch
Router
Multilayer Switch
Firewall A[[liance
Functions of all or some of these devices :
Regenerate and retransmit data signals
Maintain information about what pathways exist through the network and internetwork
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
Media
Example of media or network media are :
copper
fiber optic
wireless