tcpip協(xié)議原理兩套-第二套第02章osi和

Chapter

2 OSI

Model

&TCP/IPProtocol

SuiteThe

OSI/RMLayers

in

the

OSI/RMTCP/IP

protocol

suiteAddressing

in

TCP/IPTCP/IP

versions2.1 TheOSI/RMAn

ISO

standardOpen

System

Interconnection/

Reference

Model開(kāi)放系統(tǒng)互連/參考模型Released

in

1984Ensured

greater

compatibility

and

interoperability7

layers,

each

of

which

illustrates

aparticularnetwork

functionISO

isthe

organization,

OSI

isthe

modelOSI

is

not

a

protocol,

but

a

conceptual

modelOSIModelApplicationPresentationSessionTransportNetworkData

LinkPhysical7654321WhyLayered？AdvantagesReduces

complexityStandardizes

interfacesFacilitates

modular

engineeringEnsures

interoperable

technologyAccelerates

evolutionSimplifies

teaching

and

learningDisadvantagesStrict

layered

architecture

makes

its

software

notso

efficient.…N+1NN

1…TheFeaturesofLayeringEach

layer

concerns

on

its

own

detailsEach

layer

provides

a

service

to

the

layeraboveEach

layer

communicates

with

its

peer

layerin

another

node

through

the

use

of

acorresponding

protocolPeer-to-Peer

CommunicationPeer

Entity對(duì)等進(jìn)程/對(duì)等實(shí)體Peer

Layer對(duì)等層Interface接口Peer-to-Peer

Protocol對(duì)等層協(xié)議Service服務(wù)Peer

Layer

vs.

PeerEntityCutFTPFTP

ServerOutlookMail

ServerIEWWW

ServerLayer

7Layer

7OutlookIEFTP

ServerMail

ServerCutFTP

WWW

ServerMultiple

entities

in

one

layerPeer

entity：存在通信關(guān)系的對(duì)等層實(shí)體Multiple

protocols

in

one

layerProtocol：對(duì)等實(shí)體間的通信規(guī)則SMTPHTTPFTPDataExchange:EncapsulationSourceDestinationTNDLUnitAotocol

Data議數(shù)據(jù)單S數(shù)據(jù)段Segment分組Packet幀F(xiàn)ramePhPDU：Pr

數(shù)據(jù)Data協(xié)

元Postal

Delivery交通同層間需要約定規(guī)則——協(xié)議2.2 Layers

in

theOSI/RMApplicationPresentationSessionTransportNetworkData

LinkPhysical7654321Network

processes

to

applicationsData

representationInter-host

communicationEnd-to-endconnectionsAddressing

and

best

pathAccess

to

mediaBinary

transmissionPhysical

LayerDa inkLayerPoint-to-Point

DeliveryNetwork

LayerHost-to-Host

DeliveryTransportLayerReliableEnd-to-End

Delivery

of

aMessageSession

LayerPresentation

LayerApplication

Layer2.3 TCP/IP

Protocol

SuiteOSI/RMTCP/IPThe

historical

andtechnical

openstandard

oftheInternetWanted

a

networkthat

could

surviveany

conditions,even

a

nuclear

warData

LinkPhysical7

Application6

Presentation5

Session4

Transport3

Network21ApplicationTransportInternetNetworkAccessSocketTCP/IP協(xié)議FTPHTTPSMTPDNSTCPUDPIPLANsMANsWANsDNSTFTPSNMPICMPIGMPARPRARPMultiplexing

of

TCP/IP

ProtocolsFTPSNMPTFTPTCPICMPIPARPEthernetsoftwareEthernethardwarePortProtocol

IDTypeMACnet2321SMTP2516169617UDP10800H0806H2.4 AddressinginTCP/IPAddressPhysical

address物理地址IP

addressIP地址Portaddress端口地址標(biāo)識(shí)通信節(jié)點(diǎn)節(jié)點(diǎn)所屬LAN或WAN指定LAN或WAN內(nèi)唯一鏈路地址/硬件地址0x0005.5D06.1418標(biāo)識(shí)通信節(jié)點(diǎn)的網(wǎng)絡(luò)連接Internet指定Internet內(nèi)唯一網(wǎng)絡(luò)地址4標(biāo)識(shí)通信進(jìn)程操作系統(tǒng)指定一臺(tái)計(jì)算機(jī)內(nèi)唯一21,23,

25,808080,10000Relation-ship

of

Layers

andAddresses

in

TCP/IPProcessTCP

UDPIP

andotherprotocolsUnderlyingphysicalnetworksApplicationlayerTransportlayerNetworklayerNetworkAccesslayerPhysical

addressIP

addressPortaddressExample

1Example22.5 TCP/IPVersionsVersion

4（current）Insufficient

address

space:

32-bitInefficient

mechanism:

poor

QoS

and

securityVersion

5A

proposal

on

the

OSImodelNever

went the

proposal

stageVersion

6（future）Only

change

network

layer

protocols:

IPv6,

ICMPv6Large

address

space：128

bitImprove

the

weakness

of

version

42.6

Summary對(duì)分層網(wǎng)絡(luò)協(xié)議體系的理解不同節(jié)點(diǎn)：層次組成不同，作用不同橫向理解：虛通信，對(duì)等實(shí)體，協(xié)議，PDU縱向理解：封裝與解封，服務(wù)，接口