Tài liệu giảng dạy CCNA - module 01 chapter 02 -The TCP IP and OSI Networking Models

The TCP/IP Application Layer TCP/IP application layer protocols provide services to the application software running on a computer.. The application layer does not define the applica

Module 01 InterNetwork Overview

Chapter 02 The TCP/IP and OSI Networking Models

Table of Content

1 The TCP/IP protocol architecture

2 The OSI model.

1 THE TCP/IP PROTOCOL

ARCHITECTURE

The TCP/IP Application Layer

 TCP/IP application layer protocols provide

services to the application software running

on a computer The application layer does

not define the application itself, but rather it defines services that applications need—like the ability to transfer a file in the case of

HTTP In short, the application layer

provides an interface between software

running on a computer and the network

itself.

The TCP/IP Application Layer (cont.)

 First, the request for the file and the actual transfer of

the file are performed according to the Hypertext

Transfer Protocol (HTTP).

 The other protocol used is the Hypertext Markup

Language (HTML) HTML defines how Bob’s web browser should interpret the text inside the file he just received.

TCP/IP Network

Give me your home page

This is file home.htm

Web

client

The TCP/IP Application Layer (cont.)

 To get the web page from Larry, Bob sends something called an HTTP header to Larry This header includes

the command to “get” a file.

 The response from Larry includes an HTTP header as

well, with something as simple as “OK” returned in

The TCP/IP Transport Layer

HTTP Get

HTTP Get TCP

HTTP Ok Web page TCP

TCP Acknowledgment

TCP Acknowledgement

Please Reliably

Send This, Mr TCP!

Web server

Web client

Summary: Same-Layer and Adjacent-Layer

The TCP/IP Internetwork Layer

 IP defines logical addresses, called IP addresses, that allow each

TCP/IP speaking device (called IP hosts) to communicate

 It also defines routing—the process of how a router should

forward, or route, packets of data.

HTTP Get HTTP Get TCP

HTTP Get TCP

IP

Destination 1.1.1.1 Source 2.2.2.2

Bob 2.2.2.2

Larry 1.1.1.1

The TCP/IP Network Interface Layer

 The network interface layer defines the

protocols and hardware required to deliver

data across some physical network The term

network interface refers to the fact that this

layer defines how to connect the host

computer to the network; it is the interface

between the computer and the network.

 The network interface layer includes a large

number of protocols: LAN standards such as Ethernet, WAN standards such as PPP, Frame Relay.

Encapsulation example: E-mail

2 THE OSI MODEL

OSI reference model development

 Researched and developed by the ISO - I nternational

O rganization for S tandardizations.

 1977: establish a subcommittee to develop a

communications architecture.

 1984: publish ISO-7498, the O pen S ystem

I nterconnection (OSI) reference model.

OSI reference model

 The OSI reference model : A framework that is used

to understand how information travels

throughout a network

 It provided vendors with a set of standards

that ensured greater compatibility and

interoperability between the various types of

network technologies that were produced by

the many companies around the world

Proprietary vs Open vs Open

Comparing TCP/IP with OSI

Comparing TCP/IP with OSI (cont.)

Similarities:

Both have layers

Both have application layers, though

they include very different services

Both have comparable transport and

Comparing TCP/IP with OSI (cont.)

Differences:

TCP/IP combines the presentation and

session layer issues into its application

layer.

TCP/IP combines the OSI data link and

physical layers into the network access

layer.

TCP/IP appears simpler because it has

fewer layers.

Layers of OSI reference model

OSI layers: layer 1

OSI layers: layer 2

OSI layers: layer 3

OSI layers: layer 4

OSI layers: layer 5

OSI layers: layer 6

OSI layers: layer 7

OSI layers: Summary

OSI reference model (cont.)

 Dividing the network into seven layers provides

the following advantages:

 It breaks network communication into smaller,

more manageable parts

 It standardizes network components to allow

multiple vendor development and support

 It allows different types of network hardware and software to communicate with each other

 It prevents changes in one layer from affecting

other layers

 It divides network communication into smaller

parts to make learning it easier to understand

Benefits of layered protocol

OSI Encapsulation Process

Encapsulation example: E-mail

 You learned about how TCP/IP protocols at the various

layers work with each other and how TCP/IP encapsulates

data

 Each layer provides a service to the layer above it in the

protocol specification.

 Each layer communicates with the same layer’s software

or hardware on other computers.

 To accomplish these tasks, the data is encapsulated

progressively with new headers when sending the data and

is de-encapsulated when receiving the data.