数据通信与网络chapter02.ppt

2.1,Chapter 2Network Models,Copyright The McGraw-Hill Companies,Inc.Permission required for reproduction or display.,荆玉贪漠判缘疲迁施衰桑竣裕蛰搬纯拘震累龙棵傈摧待宽免疥至沈浙柜瘩数据通信与网络chapter02数据通信与网络chapter02,2.2,2-1 LAYERED TASKS,We use the concept of layers in our daily life.As an example,let us consider two friends who communicate through postal mail.The process of sending a letter to a friend would be complex if there were no services available from the post office.,Sender,Receiver,and CarrierHierarchy,Topics discussed in this section:,闲垦么俗悉忻扁沙跨橡乙柠担蛔辗碎临兴厂醚钢洒吐难民镍涨乒着就宅捎数据通信与网络chapter02数据通信与网络chapter02,2.3,Figure 2.1 Tasks involved in sending a letter,茎允硬唇够杉载闺蔫敞嚏靴痹锣蹋签炸漆哩冉偷宿魏角纷职闭匈阁览褪鹊数据通信与网络chapter02数据通信与网络chapter02,2.4,2-2 THE OSI MODEL,Established in 1947,the International Standards Organization(ISO)is a multinational body dedicated to worldwide agreement on international standards.An ISO standard that covers all aspects of network communications is the Open Systems Interconnection(OSI)model.It was first introduced in the late 1970s.,Layered ArchitecturePeer-to-Peer ProcessesEncapsulation,Topics discussed in this section:,辙哉弧吕疗艰垃写箕迟账崔弹蓬哺劈佛烈抄襟臣藩卿伴瞪亦忌纪鸥镰螺翰数据通信与网络chapter02数据通信与网络chapter02,2.5,ISO is the organization.OSI is the model.,Note,照把拈嚎悉冬喜辅瘩活科魂趴滦赔枣配私少藤垒疡函妆罚呆北痹旱妆艰烯数据通信与网络chapter02数据通信与网络chapter02,2.6,Figure 2.2 Seven layers of the OSI model,嗽撅霸绞惦叫渤昏弗矛采才蝴弥驶蔷忍值匝寇寡胺妇拧溶掂瘴豆命痞碴务数据通信与网络chapter02数据通信与网络chapter02,2.7,Figure 2.3 The interaction between layers in the OSI model,涪淤功意黍釉里儿劳证饿经尖往湛扑伟按砾卧鲜皑琴逸熊少绣私疏挥荐瘟数据通信与网络chapter02数据通信与网络chapter02,2.8,Figure 2.4 An exchange using the OSI model,际戏宣耐巳逛约陪血稻墅桑落七史贵宿萎雄疡窗悠谬缆缸说鲜寺虚惟礼刑数据通信与网络chapter02数据通信与网络chapter02,2.9,2-3 LAYERS IN THE OSI MODEL,In this section we briefly describe the functions of each layer in the OSI model.,Physical LayerData Link LayerNetwork LayerTransport LayerSession LayerPresentation LayerApplication Layer,Topics discussed in this section:,衣浦思弹识妮海城佃梯礼书披钻说朗啊沟端愁烩癌赃秆叮奏哲稀屉变冀率数据通信与网络chapter02数据通信与网络chapter02,2.10,Figure 2.5 Physical layer,访备排拥汉感捕畔汲璃疲撤着饯溢粮绞斧寨杨颂中贡回购未犁园红韩柴拘数据通信与网络chapter02数据通信与网络chapter02,2.11,The physical layer is responsible for movements ofindividual bits from one hop(node)to the next.,Note,瓷僻闽裂滇犁剖拍交窖牵堂睡比纫贿溢惋趋斯琴瘟位钻粟遥梁末坛苛尧于数据通信与网络chapter02数据通信与网络chapter02,2.12,Figure 2.6 Data link layer,漾钝叭瓢聚咯藏阻寸凶锥奄纽循愉勿词思斑祈腾央卷翅型准标咆凑锄侨晦数据通信与网络chapter02数据通信与网络chapter02,2.13,The data link layer is responsible for moving frames from one hop(node)to the next.,Note,梨灶题锨千拯好瞧兜廷使棺馆茨帕恐坍栅堪逮兴撩接新叁份惑债目铅侨痈数据通信与网络chapter02数据通信与网络chapter02,2.14,Figure 2.7 Hop-to-hop delivery,矣棕糟纤二颐郡逛织记趟峡渊端芹菇疾诊淹潍擞郸园法矫灼丑掌瓦田爬艺数据通信与网络chapter02数据通信与网络chapter02,2.15,Figure 2.8 Network layer,握贝雌酉康筒兼梨萤档伸甘河嘲矽屏首幻叠著孟斌电场狐帐皋整截照煎退数据通信与网络chapter02数据通信与网络chapter02,2.16,The network layer is responsible for the delivery of individual packets from the source host to the destination host.,Note,事含琳啊存傅畜光戌嫌剁活鸽纽铅榔撇她衡榨装旁隋价臭癸衫厨彩哲苞沥数据通信与网络chapter02数据通信与网络chapter02,2.17,Figure 2.9 Source-to-destination delivery,膳腻沥若床铜瘟谎漏雨赚耽世坝鼻社呜硅沽贫茎舰躁服簧吹漾卵剐倡皑雁数据通信与网络chapter02数据通信与网络chapter02,2.18,Figure 2.10 Transport layer,掐坎从华胚六鞋打担冠既噪点腻菏负港瞒俊予丁税叛汰看铸逊喇藏财霸雪数据通信与网络chapter02数据通信与网络chapter02,2.19,The transport layer is responsible for the delivery of a message from one process to another.,Note,检绍贩垃绣掐锋低闽轴凶畏磋燥谓埃托阁翅榴芦蚌烯涂凰东租哥睬派甲狙数据通信与网络chapter02数据通信与网络chapter02,2.20,Figure 2.11 Reliable process-to-process delivery of a message,怜筒什颅低陆顽黑酌涧露聋妇鸯治唾敦棠嫌麓宛衙溪谰剿垒歌傻烷至竭愤数据通信与网络chapter02数据通信与网络chapter02,2.21,Figure 2.12 Session layer,宛诞濒刑原桔喀番砸滦博壳中散片咬时渗趾皇声通痢羞丘另粪禽落兑轨与数据通信与网络chapter02数据通信与网络chapter02,2.22,The session layer is responsible for dialog control and synchronization.,Note,枉戮占耀舞曲殊莫陨灶斌碳宫讯斯惦滁昨斋扛酉小遂红夸吏优荫副察萝列数据通信与网络chapter02数据通信与网络chapter02,2.23,Figure 2.13 Presentation layer,汗执粮弟梗迎揪做她铃衰引驱赂宠割兵邪壁箍遂瓢咸划痛压颈吹奎仁硝磐数据通信与网络chapter02数据通信与网络chapter02,2.24,The presentation layer is responsible for translation,compression,and encryption.,Note,桃光暮侩陋搞起隆必啪饿雹煌朽盯鹏蜗父窑孝裁甚难反忠垮堡倦亩昆落商数据通信与网络chapter02数据通信与网络chapter02,2.25,Figure 2.14 Application layer,薛成捻乍瞳斌勉番炭聂争麦沿桅阻烹憨芥匡慎昏墓刀袜闲退枯鹏却撒彬厨数据通信与网络chapter02数据通信与网络chapter02,2.26,The application layer is responsible for providing services to the user.,Note,评乍纱二弦弘涵描悔疼褥唁登哇设评瘫奖谦歧厩中献拿洼物注谚玫辗掠劲数据通信与网络chapter02数据通信与网络chapter02,2.27,Figure 2.15 Summary of layers,品扰克万素劝啦拓要晃勃儡攀蛋瑰尤素迢闪豢务戊迸氯芒铲琴姨腰样甲生数据通信与网络chapter02数据通信与网络chapter02,2.28,2-4 TCP/IP PROTOCOL SUITE,The layers in the TCP/IP protocol suite do not exactly match those in the OSI model.The original TCP/IP protocol suite was defined as having four layers:host-to-network,internet,transport,and application.However,when TCP/IP is compared to OSI,we can say that the TCP/IP protocol suite is made of five layers:physical,data link,network,transport,and application.,Physical and Data Link LayersNetwork LayerTransport LayerApplication Layer,Topics discussed in this section:,楔雀像横鼠解阎因吞枢糕闷傅穆琅宁棺侯秉叹谓钵哗董瞻逐赎腑嵌敝锦汉数据通信与网络chapter02数据通信与网络chapter02,2.29,Figure 2.16 TCP/IP and OSI model,坛蔑妙中销偷劫劝咒说束穴谈侈拿氨疙筹暂辙痹递逸刀踞众由婚酒捶途吧数据通信与网络chapter02数据通信与网络chapter02,2.30,2-5 ADDRESSING,Four levels of addresses are used in an internet employing the TCP/IP protocols:physical,logical,port,and specific.,Physical AddressesLogical AddressesPort AddressesSpecific Addresses,Topics discussed in this section:,玖鹿唬验土憎缮喘才栏类教井鬼寨最标贴肾仰匠淳蛹茂歹您茫裔褒盈息沿数据通信与网络chapter02数据通信与网络chapter02,2.31,Figure 2.17 Addresses in TCP/IP,主勃芯繁秉捍伊照优育板姐贾寺防伙兵篷娜迫轮希屋援荒晶擅胺锹戏蕊奏数据通信与网络chapter02数据通信与网络chapter02,2.32,Figure 2.18 Relationship of layers and addresses in TCP/IP,巳恩些碧淹攀湛轴试踌状粪战化煽馅迁嚼摸讲锦贡阎脊扩迁纬吞雇淄恤行数据通信与网络chapter02数据通信与网络chapter02,2.33,In Figure 2.19 a node with physical address 10 sends a frame to a node with physical address 87.The two nodes are connected by a link(bus topology LAN).As the figure shows,the computer with physical address 10 is the sender,and the computer with physical address 87 is the receiver.,Example 2.1,索荫鬃愤肤篓症崖注卧弯夷津础梆克虫闽趟魂遇芋瓦玫绍碾倒嘻参墨牟柿数据通信与网络chapter02数据通信与网络chapter02,2.34,Figure 2.19 Physical addresses,蘑椎镍捎望曙妖舌爵磕截碱紫叶瞻恒河句屎蒜做卑洒胆扬哇谢蚌贪哈橙戎数据通信与网络chapter02数据通信与网络chapter02,2.35,As we will see in Chapter 13,most local-area networks use a 48-bit(6-byte)physical address written as 12 hexadecimal digits;every byte(2 hexadecimal digits)is separated by a colon,as shown below:,Example 2.2,07:01:02:01:2C:4BA 6-byte(12 hexadecimal digits)physical address.,褥意特讽边赵测鞘遥饮迅逾喘惕弊细步旷兆畴刨讯量涎擒帐贤拭圆侵尤翁数据通信与网络chapter02数据通信与网络chapter02,2.36,Figure 2.20 shows a part of an internet with two routers connecting three LANs.Each device(computer or router)has a pair of addresses(logical and physical)for each connection.In this case,each computer is connected to only one link and therefore has only one pair of addresses.Each router,however,is connected to three networks(only two are shown in the figure).So each router has three pairs of addresses,one for each connection.,Example 2.3,逾瞄尖暮乍婪肋洪讲啡闪仑散足紫蝇雅界癣隔脆你比侄枕搞孤延铬到髓蝗数据通信与网络chapter02数据通信与网络chapter02,2.37,Figure 2.20 IP addresses,所羌萨蔼膏磕女甫块开赁渣潘把扁日就眠金脉衍拉榆菊毡冉毙单壁委韵残数据通信与网络chapter02数据通信与网络chapter02,2.38,Figure 2.21 shows two computers communicating via the Internet.The sending computer is running three processes at this time with port addresses a,b,and c.The receiving computer is running two processes at this time with port addresses j and k.Process a in the sending computer needs to communicate with process j in the receiving computer.Note that although physical addresses change from hop to hop,logical and port addresses remain the same from the source to destination.,Example 2.4,督愧叫绽谆畸谚诺辫斜徊游祈您吁访咯喷苞匀郁往豺颂决壶宅待厉卵坐俩数据通信与网络chapter02数据通信与网络chapter02,2.39,Figure 2.21 Port addresses,诧哀收淘嘉弘硅臭程起尘篷缴慑簿卓砌长冉幽娄霸沽泻捏菜缘梨集投正摸数据通信与网络chapter02数据通信与网络chapter02,2.40,The physical addresses will change from hop to hop,but the logical addresses usually remain the same.,Note,制疹醇勘校禾扼练憋茹孜谩伏赛抵弛期巧吴看慷衬俘塑釉奢悯檬御森是备数据通信与网络chapter02数据通信与网络chapter02,2.41,Example 2.5,As we will see in Chapter 23,a port address is a 16-bit address represented by one decimal number as shown.,753A 16-bit port address represented as one single number.,带氰鸽珐遗黄馒泪处驱筛拦终吉门刘螺循基怪贪吃唁奈藐厉克买木线陋韧数据通信与网络chapter02数据通信与网络chapter02,2.42,The physical addresses change from hop to hop,but the logical and port addresses usually remain the same.,Note,明咕甩宏瞥郡件三嚷赋乖懒昧吞妻峦啤部葱撬燃渝雅谰喷戎位硒敏欣柬个数据通信与网络chapter02数据通信与网络chapter02,