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1、0101Lecture 29Protocols&Architecture01.Network ProtocolProtocol Agreements are rules,agreements,and commitments that all parties to collaborate in order to achieve a certain purpose in social life and need to abide by.For example,the communication process in telephone communication follows certain r
2、ules to ensure that the two parties communicate clearly express their ideas.NetworkTelephoneNetwork Protocol It is a rule,standard or agreement established by data exchange(communication)in the network to ensure that all parties to the exchange express their ideas clearly.Multiple network protocols
3、are required,and each network protocol functions differently.It defines the format and sequence of sending and receiving messages between network entities and the actions to be taken when transmitting and receiving messages.Three elements of network protocol01.Network Protocol Three elements of netw
4、ork protocolGrammarSemanticTiming：Structure(format)of data and control information.:The meaning of control information,actions and responses to be made.：Specifies the order in which operations are performed.FlagAddressCtrlDataFCSFlagHDLC0111111088可变可变16 01111110How WhatOrder01.Network Protocol Three
5、 elements of network protocolTiming：AB01.Network ProtocolTCP 3-Way Handshake to establish the connectionTCP 4-Way Handshake to release the connectionData transmission02.Network ArchitectureThe computer network is designed as a hierarchical structurecomplex information transmission is divided into se
6、veral relatively simple sub-functions,which are implemented at different levels.Each layer contains several protocols for implementing the functions of this layer.The protocol defines the communication rules between peer layers.The computer network architecture is a collection of network hierarchica
7、l models and various layer protocols.Layer 2Layer 1Layer nSystem A Express packagesWhy layering？PackagingtransportExpress FormsenderReceiverDelivery manOrder deliverytransportReceive express02.Network ArchitectureIndependentEach layer can be implemented with the most appropriate technology;Improveme
8、nts in one layer of technology will not affect other layers；The upper layer only needs to care about what services the lower layer can provide,and does not need to care about its implementation method.AdaptableAs long as the services and interfaces provided remain unchanged,the implementation of eac
9、h layer can be changed arbitrarily.The structure is clear,which makes the design,implementation,debugging and maintenance of the system simple and easy.Why layering？02.Network Architecture03.Peer Layer、Peer entity、Interface、ProtocolEntity:A hardware/software process that can send or receive informat
10、ion.Peer Layer:The same name hierarchy of two different systems.Peer entity:Two entities at the peer layer.InterfaceInterfacePeer LayerPeer LayerPeer entityPeer entityNetwork Protocol:Data communication rules between peer layers.Each layer has several network protocols.Protocol Stack:Protocol Collec
11、tion.010203Service：The lower layer provides functions for the adjacent upper layer.Interface：Service Entrance of lower layer supported to upper layer.Layer 2Layer 1Layer nSystem ASystem BLayer 2Layer 1Layer n03.Peer Layer、Peer entity、Interface、ProtocolPackagingtransportExpress FormsenderReceiverDeli
12、very manOrder deliverytransportReceive express Express packages04.04.数据传输Data encapsulationIt is the data in front of this layer plus the control information used to control the transmission process(such as address,data length,check code,etc.).These control information are collectively called the me
13、ssage header.Data decapsulationIt is to remove the message header from the received message.Layer 5Layer 4Layer 3Layer 2Layer 1SourceDestinationDDDDDDDDD:dataLayer 5Layer 4Layer 3Layer 2Layer 1H3H3H4H4H4H2H3H3H4H4H4H205.Reference modelOSI Layer 7TCP/IP Layer 4Provide users with network application s
14、ervices.Responsible for data encoding.Establish,maintain,and terminate sessions among users.Communication between processes of different computers.Implement routing for transmitted packets.Frames are reliably transmitted between nodes.Responsible for receiving and sending bitstreams between nodes.05
15、.TCP/IP Reference modelWhat layers does the TCP/IP architecture contain?What is the function of each layer?TCP/IP Protocol StackData transmission process between layers under TCP/IP Reference modelInformation exchange and remote operation services required by user processesGrouped network communicat
16、ion between processesGrouped routing on multiple networksFrame-free transmission and selection of physical signals on a link应用层（Application）传输层（Transport）网际层（Internet）网络接口层（Network Interface）应用层（Application）传输层（Transport）网际层（Internet）网络接口层（Network Interface）TCPTCP头头应用层数据应用层数据应用层数据应用层数据IPIP头头TCPTCP头头应用层数据应用层数据帧头帧头帧尾帧尾TCPTCP头头应用层数据应用层数据IPIP头头Thank you!