DFC 20143
INTRODUCTION TO NETWORK
(T1.2)
1.2.1 Explain purpose of the Cisco IOS
- embedded software architecture in all of the Cisco router
- is OS of the catalyst switches
Cisco provided network services:
- basic routing and switching function
- reliable and secure access to networked resources
- network scalability
OS (all electronic devices need OS)
a) OS shell
enables user to interface with application
b) OS kernel
communicate directly with hardware and manages how the resources are used to meet software requirement
c) Hardware
physical part of computer including underlying electronics
Router user interface
Cisco IOS use CLI (traditional console environment)
- Console
- Dialup connection
- Telnet to the router
Purpose of OS
a) GUI (enables user)
- use mouse (make selections and run programs)
- enter text and text-based commands
b) CLI os Cisco IOS switch/router (enable network technician)
- use keyboard (make selections and run programs)
- use keyboard enter text and text-based commands
All devices come with a default IOS and feature set (possible upgradable)
Access methods
- Console port
- Secure shell (SSH)
- Telnet
Cisco IOS Modes of Operation
IOS Modes
- use a
hierarchical command
structure - Each mode has a distinctive
prompt & used to
accomplish particular tasks
with a specific set of commands that are
available only to that mode
a) User EXEC Mode
monitoring commands
b) Privileged EXEC mode
accesses all router commands
c) Global Configuration mode
allow modify the running system
configuration
Cisco CLI
the primary
user interface used for configuring, monitoring, and maintaining Cisco devices
allows you to directly and simply execute
Cisco IOS commands, whether using a router console or terminal, or using remote access methods
Configuration Command Modes
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
- move user EXEC mode to privileged EXEC mode
- Use return to user EXEC mode
- exit
- end
- ^z
use the
enable command
use the disable command
to move from a specific mode to the previous more general mode (interface mode to global config)
to exit out of global configuration mode regardless of which configuration mode you are in
Works the same as end
- enter privileged EXEC mode
use the enable command
- enter global config mode
use the configure terminal command
- enter interface sub-config mode
use the interface fa0/1
command
- exit out of each mode
use the exit command
Basic IOS Command Structure
:
IOS Command Syntax
Hot Keys and Shortcuts
IOS Help Features
IOS Context-Sensitive Help
- 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.
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”, “ous command”, “Incomplete command”, or “Incorrect command”
1.2.4 How devices communicate accross network media
Overview of Network Components
Devices
Media
Services
End Devices
Intermediary Network Devices
- regenerate and retransmit data signals - maintain information about what pathway 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 / deny the flow of data, based on security settings
Network Media
What is the maximum distance that the media can successfully 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?
Networks are divided into two types, a LAN (Local Area Network) or a WAN (Wide Area Network), which are generic terms referring to two important basic types of networks.
- K = kilo = 1,000 bits
- M = mega = 1,000 kilo = 1,000,000 bits
- G = giga = 1,000 mega = 1,000,000,000 bits
- T = tera = 1,000 giga = 1,000,000,000,000 bits
Network Representations
Network media is the actual path over which an electrical signal travels as it moves from one component to another. As long as there is require no specific bearer and radiate their signals as electromagnetic waves.
Topology Diagrams
Physical Topology
Logical Topology
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