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1、1,Chap 3,Switching & Forwarding Circuit Switching Packet Switching Datagram (connectionless) Virtual Circuit (connection-oriented) Source Routing Bridge and LAN Switch Learning Bridge Spanning 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 Switchin
2、g,Each switch 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
3、2系统方法课件-08 syllabus 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 well No upper bound of the header size Strip the first element rather than rotate the header. OR Create a pointer to the cu
4、rrent “next port”,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 & Forwarding Circuit Switching Packet Switching Datagram (connectionless) Virtual Circuit (connection-oriented) Source Routing Bridge and LAN Switch Learning Bridge Spanning Tree Algorithm,距
5、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 bridge accept and forward strategy level 2 connection Switch & 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
6、统方法课件-08 syllabus 2,8,Learning Bridges,Do not forward when unnecessary Maintain forwarding table Host Port A 1 B 1 C 1 X 2 Y 2 Z 2 The table can be maintained by a human. But it a burden Learn table entries based on source address Table is an optimization; need not be complete A timeout is associate
7、d 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 1，3，5，13，15，17 Required Reading Stallings chapter 3.1-3.2,犀志族乔卤俯讥子榴陕焙调剃徘
8、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 syllabus 2,11,Chap 4,IP (include subnet & CIDR) ARP ICMP IPv6,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 lost packets are delivered o
9、ut of order duplicate copies of a packet are delivered packets can be delayed for a long time Datagram 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,Glob
10、al Addresses,Properties globally unique hierarchical: network + host,朔赣册宛弃学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: subnet Subnet masks define variable partition of host part Subnets visible only within site,哟秆链时
11、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 Example,Forwarding table at router R1 Subnet Number Subnet Mask Next Hop 128.96.34.0 255.255.255.128 interface 0 128.96.34.128 255.255.255.128 interface 1 128.96.33.0 255.255.255.0 R2,Forwarding table at router R2 Subnet
12、Number Subnet Mask Next Hop 128.96.34.0 255.255.255.128 R1 128.96.34.128 255.255.255.128 interface 0 128.96.33.0 255.255.255.0 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. CI
13、DR collapses the multiple addresses onto one address Such as the class C network number from 192.4.16-192.4.31 has the same top 20 bits. IP forwarding revisited: The “longest match” princeple Such 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
14、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,IP ARP ICMP IPv6,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昏系统方法课件-08 syllabus 2系统方法课件-08 syllabus 2,19,ARP table of IP to physical address bindings broadcast request if IP address not in table target machine responds with its physical address table entrie
15、s 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 cache 2. A broadcasts ARP request 3. C adds As information into ARP cache 4. C responds ARP r
16、equest 5. A adds Cs information into ARP cache 6. 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,IP ARP ICMP IPv6,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 Pro
17、tocol,ICMP When a router receives an IP packet and finds errors, what should it do? Used by the routers to report errors and unexpected 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
18、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,IP ARP ICMP IPv6,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 syllabus 2系统方法课件-08 syllabus 2,24,Problems with IPv4,Address depletion 232=4.3 billion addresses Most organizations apply for class B network. Does not support host mobility
19、Not 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 coexist for years What IPv6 has: IPv6 addresses are 16 bytes long, instead of 4 bytes in IPv4. Provides an effectively unlimited supply of Internet addresses IPv6 he
20、ader contains only 7 fields (versus 13 in IPv4) Allows faster process of packets IPv6 has better support for options. IPv6 improves security (authentication 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 Add
21、resses,Notation 47CD:1234:4422:AC02:0022:1234:A456:0124 47CD: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 address Multicast addr
22、ess Others (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
23、 options - provides information for the destination Fragmentation header - provides information in the event that packet fragments must be reassembled. Hop-by-hop header - provides information that each router must examine Routing header - provides additional routing information Security header - in
24、dicates the packets payload has been encrypted Authentication 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,Compatibility with IPv4, IPv4 will be around for a long time. IPv6 allows IPv4 addresses. What happens when an IPv6 packet has to p
25、ass 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 address?,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 4，21，45，58 Review
26、question 1. 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-
27、Stream (TCP) Connection Establishment/Termination Sliding 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 IP Adds multiplexing by ports simply passes IP through to the upper (application) layers No flow control, N
28、o congestion control, No connection Unreliable and unordered datagram service Gives apps the option to send packets unreliably Useful for multicast apps Minimal connection setup time : “connectionless” Low delay transmission for interactive text/audio/video Build own application-level protocol on to
29、p 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 process Dest port for UDP receiving process Length in bytes of UDP header + payload Checksum over UDP header + payload,Source Port #
30、,Dest. Port #,UDP length,Checksum,16,32,UDP payload data,UDP payload,IP hdr,UDP hdr,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-oriented Reliable delivery of packets, in-order delivery Full duplex Flow control, Congestion control, Connection management,
31、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 Pipe 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
32、 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
33、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 agree to a credit of 200 bytes Assume entities send 100 bytes
34、 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 10 Review question 1. 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,