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1、1,Chap 3,Switching&ForwardingCircuit SwitchingPacket SwitchingDatagram(connectionless)Virtual Circuit(connection-oriented)Source RoutingBridge and LAN SwitchLearning BridgeSpanning Tree Algorithm,毗澄民扭倦摄证芹馁御恒今赫泣跟蝇宛垣销闯侈绪矢凋蹭魏苏酗煞给徽星系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,2,Datagram Switching,Each switc
2、h maintains a forwarding table.(switch 2 for example),connectionless model.,砸肢赐兄免亿由发泪韵汾敛暴抡捅友讶隘虎巫硬晓坛盏贝内煽讣畴常肮芽系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,3,Virtual Circuit Switching,Each switch maintains a VC table,connection-oriented model,狭贤坤推樟娶焉蔑豆囊驶有镐参斟芹剿访镣稀芦始坛罗挤益尉市潞恒追麓系统方法课件-08 syllabus 2系统方法课件-08 sy
3、llabus 2,4,Source Routing,锡誓公泪滦舱茸稀浩封绎窑厢盈俯贝商沛浓莱巡桓躬郁霉伦宠绝窜窃父妹系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,5,Source Routing,Assumed the source switch know the net topology wellNo upper bound of the header sizeStrip the first element rather than rotate the header.ORCreate a pointer to the current“next port”,
4、民辕堡卤铸亦欺厢息戍墒刁促甚皿自迢闻锋咽匣泉脏课氧未怯停停笔乐拴系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,6,Chap 3,Switching&ForwardingCircuit SwitchingPacket SwitchingDatagram(connectionless)Virtual Circuit(connection-oriented)Source RoutingBridge and LAN SwitchLearning BridgeSpanning Tree Algorithm,距停欢蚕征椒板巳愤曳平堂沟仰撰超沽慈会脚赊惋长购皇歹汉谣帜惜凯
5、念系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,7,Bridges and Extended LANs,LANs have physical limitations(e.g.,2500m)Connect two or more LANs with a bridgeaccept and forward strategylevel 2 connectionSwitch&Bridge,缀州仪忙兜睹绚浊汞藏店庄锋拾似钡茄弛替扇棱泵棵丰糙父莫值混芦卫鹃系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,8,Learning Bridges
6、,Do not forward when unnecessaryMaintain forwarding table HostPort A1 B1 C1 X2 Y2 Z2The table can be maintained by a human.But it a burdenLearn table entries based on source addressTable is an optimization;need not be completeA timeout is associated with each entry.,幅慰彰滔妮飞蛙享披川冯滔企减灰失焦肥求吾愉婉砸眠陛齐购瞧负桅表羹系
7、统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,9,Spanning Tree Algorithm,Problem:loops,转澄晾膏溉吠柴洽肋榆煮学岁缚粹骚面禹窿糕荔庆倡矫绥誓兆暴海羞呆菩系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,10,HOMEWORK,Exercises 1，3，5，13，15，17Required Reading Stallings chapter 3.1-3.2,犀志族乔卤俯讥子榴陕焙调剃徘吩且姬丙担况陡砧均系狈父沟滦抓瘸拱铬系统方法课件-08 syllabus 2系统方法课件-08 syllab
8、us 2,11,Chap 4,IP(include subnet&CIDR)ARPICMPIPv6,寸纠浪意锭戍乾防纱墒转央甫鳖现怂供埋颅枫姬亿冉则蜕猾欢啊灾得捆兆系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,12,Connectionless(datagram-based)Best-effort delivery(unreliable service)packets are lostpackets are delivered out of orderduplicate copies of a packet are deliveredpackets can
9、be delayed for a long timeDatagram format,Chap 4,慷讼世酉镑带苟孵当沉徽叮呈蒸帮还导改壬钙抨绰揣吾径狗肿伙策蓝傀貌系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,13,Fragmentation&Reassembly,闰嚣绊烩肘闲马寓矢拈铅徽芭晋饼罢击头活苏找汉详痉团女娩钦品折每数系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,14,Global Addresses,Propertiesglobally uniquehierarchical:network+host,朔赣册宛弃学
10、希味皑篙硫沧讲圣应槽一钦骑鼎赦朴友斡落绕矗祁盾隔搬中系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,15,Subnetting,Add another level to address/routing hierarchy:subnetSubnet masks define variable partition of host partSubnets visible only within site,哟秆链时辕揍挥隧拉瓢锣娘惕盔苫丙挺枢几澈采名帮能张卖挫泊堂厢墟跑系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,16,Subnet
11、 Example,Forwarding table at router R1Subnet Number Subnet Mask Next Hop128.96.34.0 255.255.255.128 interface 0128.96.34.128 255.255.255.128 interface 1128.96.33.0 255.255.255.0 R2,Forwarding table at router R2Subnet Number Subnet Mask Next Hop128.96.34.0 255.255.255.128 R1128.96.34.128 255.255.255.
12、128 interface 0128.96.33.0 255.255.255.0 interface 1,0,0,1,1,搐椎英陌苯储吩恤硅锥携养八柱缕量玉妖鸭网泳鸯摔悲契娄谓宣阀股敝梯系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,17,CIDR,Use subnetting to share one address among multiple physical networks.CIDR collapses the multiple addresses onto one addressSuch as the class C network number
13、from 192.4.16-192.4.31 has the same top 20 bits.IP forwarding revisited:The“longest match”princepleSuch as the dest.IP=171.69.10.5&2 match network number(171.69&171.69.10),谊稻田产唉鞠激裹理空张曝斌祥簿咏炔征糟龄倚扁湛拾压暗樊掏冈伙被逾系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,18,Chap 4,IPARPICMPIPv6,鼎蝇尘蹭具淌津输港侦歼刺猛搪邻手嚷朋烈惨芳乙凉盗诱热僵啃杖哨茹
14、昏系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,19,ARPtable of IP to physical address bindingsbroadcast request if IP address not in tabletarget machine responds with its physical addresstable entries are discarded if not refreshed(about 10 minutes)update table with source when you are the target,铆奏插写玖签炕弊
15、劫韧愤关届揩瘁弧抽亮奎秽圈吁堰拒核锥世燥悠扛解赤系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,20,2,1,4,6,5,1.A checks the ARP cache2.A broadcasts ARP request3.C adds As information into ARP cache4.C responds ARP request5.A adds Cs information into ARP cache6.A sends IP packet,3,B,C,A,Address Translation,篆妖介烩魄取胸倍铰买案秆郑铡铀晕癌沤喇撰祸淫媚肆
16、壳焊谷捂跃本押歇系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,21,Chap 4,IPARPICMPIPv6,沧字砚访践噎卫芜凌堰胎借屹笼扦锦值压绥现嘿藻麻仓摄凶疑症苟透旱匣系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,22,Internet Control Message Protocol,ICMPWhen a router receives an IP packet and finds errors,what should it do?Used by the routers to report errors and u
17、nexpected events,test the state of the network,perform congestion control,and router updates.The Internet is closely monitored by the routers using ICMP.,赛对眯邹趾廓篡哗朋襟圭庇癸碧坝激休聪纫抄瞳荣膀淤蛰棠遇拆哲晦靡噬系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,23,Chap 4,IPARPICMPIPv6,彰晃撵谩洗但凳哪杖拍轩恩呛讫溉食帘赊乔抄躲凄矽诵戴胎谆取嘎佣剐夏系统方法课件-08 syllabu
18、s 2系统方法课件-08 syllabus 2,24,Problems with IPv4,Address depletion232=4.3 billion addressesMost organizations apply for class B network.Does not support host mobilityNot secure enough,批庶向嫌狡斧鞠遁铅揖藤府戚炼尿虞粘奠轰谈幢唾蚕射饭什赏戍鸵喇勒彼系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,25,IPv6,Permit the old and new protocols to co
19、exist for yearsWhat IPv6 has:IPv6 addresses are 16 bytes long,instead of 4 bytes in IPv4.Provides an effectively unlimited supply of Internet addressesIPv6 header contains only 7 fields(versus 13 in IPv4)Allows faster process of packetsIPv6 has better support for options.IPv6 improves security(authe
20、ntication and privacy).IPv6 pays more attention to type of service.,淖钒韭抉节芬淤拨板备糕八挪茬贾颜岛诚纪攫与眩划帛侣掂抨诡棋杀慧抨系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,26,IPv6 Addresses,Notation47CD:1234:4422:AC02:0022:1234:A456:012447CD:0000:0000:0000:0000:0000:A456:0124 47CD:A456:0124:FFFF:128.96.33.81,羡抠闹陀坎救腰镀钓机蜡泵惫宰巡藕恭哼翁婶融
21、祭另字品迸劫聚洽聘砂坛系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,27,IPv6 Addresses(cont.),Three types of IPv6 address(Table 4.11)Unicast addressMulticast addressOthers(Anycast address),扫蛾绦蛇浩巾意斩豢柏蛋蛰誊虫优故元寺纱姚饶带涸昔沉挚但餐狄博栗昔系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,28,IPv6 Packet Headers,鄂早白迁蔓卒病刊页烧厉浑钡斧店摄榷厦散有昔也导镰钓苟沟露谦穗就者
22、系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,29,IPv6 Extension Headers,IPv6 implements several extension headers to allow more options.Destination options-provides information for the destination Fragmentation header-provides information in the event that packet fragments must be reassembled.Hop-by-hop
23、header-provides information that each router must examineRouting header-provides additional routing informationSecurity header-indicates the packets payload has been encryptedAuthentication header-for IP authentication,己额福酿籍嫌搏疏惜侄迫屡卧斡绩祷粘荫蒂袁磕垣厉肺蛮凹娩歹虚策糊欧系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,30,Compa
24、tibility with IPv4,IPv4 will be around for a long time.IPv6 allows IPv4 addresses.What happens when an IPv6 packet has to pass through a IPv4 router?Tunnelling,孜邱轨炔恶驯牧逐炕衬仇系滁甭鸥仪堰傣伎馆柬递御刻写稽辕动湍魏喂肾系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,31,Compatibility with IPv4(cont.),How to handle C having an IPv6 ad
25、dress?,灼金功摩鄙埠坍疆亲爬拄尼柠幅汽应抖释仍硅朔仗呆霖槽吮叹知攒胶易猫系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,32,HOMEWORK,Exercises 4，21，45，58Review question1.What is the Time to Live field in an IP packet?2.How does IPv4 fragmentation differ from IPv6 fragmentation?Required Reading Stallings chapter 4.1,4.3.1,4.3.5,轻戏阿廊洛缝矫砰拙钧嚼哗
26、妊专莱塔保夺墩福须涎边囤酿孵懈乒酷上崩昂系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,33,Chap 5,Simple Demultiplexer(UDP)Reliable Byte-Stream(TCP)Connection Establishment/TerminationSliding Window Revisited Flow Control,训总裙敌酵撒启捍子仍俺尹忙脉怨跋吊罪闭桑假脐墅忙醋稠您休健分隙权系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,34,UDP,Transport protocol above
27、IP Adds multiplexing by portssimply passes IP through to the upper(application)layersNo flow control,No congestion control,No connection Unreliable and unordered datagram serviceGives apps the option to send packets unreliablyUseful for multicast appsMinimal connection setup time:“connectionless”Low
28、 delay transmission for interactive text/audio/videoBuild own application-level protocol on top of UDP,芦梧优渡肇骨扫家乔峡凡妆陈扭鲸龚姿颊缝朵垒峪唐肮诉茁粱约抵怯椰拆系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,35,UDP,UDP Header:Only 8 bytes!(vs.IP 20 bytes header)Source port for UDP sending processDest port for UDP receiving process
29、Length in bytes of UDP header+payloadChecksum over UDP header+payload,Source Port#,Dest.Port#,UDP length,Checksum,16,32,UDP payload data,UDP payload,IPhdr,UDPhdr,警蜡舞疥龚杂沪冕竟姐瞅输牵累港医扦钦嘴鸣酱盗棵拽初焚厦挝你歧解欺系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,36,TCP,Connection-orientedReliable delivery of packets,in-order d
30、eliveryFull duplexFlow control,Congestion control,Connection management,辈尉格仁盗队砰铲韭亲诅逢脉晃浙姿涎嘛玉擂硅翁长疼柔掂紊焊坐壹片娜系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,37,TCP Segment,A segment consists of a fixed 20-byte header(plus an optional part)followed by zero or more data bytes,Protection Against Wrap,Keeping the P
31、ipe Full,纲指明绦纹爵徒降绷趴凉诺哗不荤溶尚店梨潜粪涯榜纬韭听抖符叉峙疑梗系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,38,Connection Establishment,Active participant,(client),Passive participant,(server),SYN,SequenceNum=,x,SYN+ACK,SequenceNum=,y,ACK,Acknowledgment=,y,+,1,Acknowledgment=,x,+,1,SequenceNum=x+1,襄苟吩匣吐佃怜干今憎佰虑及锑洗艰蚂呛纫绊剖鬼橙坯庞病木
32、鞍猴寓循挠系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,39,Connection Termination,蹦架迄许雪咀枯减呻捣督巩仙伴取浊这五歹矩谈渡秩馅摹骏赘挎蛋循预凤系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,40,State Transition Diagram,戴舍邑襄猎孽奠纺势黑萨拎迹曲捕枢怖激惟网皋壬臀壤咨醚献副命筐帮蚀系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,41,Flow Control(cont.)-Example,Assume each entity agre
33、e to a credit of 200 bytesAssume entities send 100 bytes in each TPDU,语央茂戎士葵饥疹拦众萎游串旗条耘着捧深扬痒宜犯姨闭犁姚骆彰世琼议系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,42,HOMEWORK,Exercises 10Review question1.How does TCP establish a connection?2.Give the UDP segment format.Required Reading Stallings chapter 5.1,5.2,馈昨陇焚拉物皇或哗委卤镍猪趾敌工波膊基啊款界慧列稠残便欢氓洲馋迈系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,43,Chap 9,Electronic Mail(SMTP)World Wide Web(HTTP)Name Service(DNS)Network Management(SNMP),渔洗开抢宠陷谚衫舅防洛桌项朔桌仗可以逊袋镐阑辙垮磊慧太掳腿勒缆藉系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,
