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

: zo

IOS Command Syntax

zo2

Hot Keys and Shortcuts

zo3

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

device

internetwork

service

End Devices

end device

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

intermediary device

Network Media

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

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

physical topology

logical topology

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