以太網(wǎng)技術(shù)和以太網(wǎng)交換市公開課一等獎省賽課獲獎?wù)n件

第六章以太網(wǎng)技術(shù)和以太網(wǎng)交換以太網(wǎng)技術(shù)和以太網(wǎng)交換第1頁主要內(nèi)容

介紹橋接和交換技術(shù)、生成樹協(xié)議（STP）以太網(wǎng)技術(shù)和以太網(wǎng)交換第2頁6.110Mbit/s和100Mbit/s以太網(wǎng)10Base5100BaseTX10BaseT100BaseFXMediaMaximumSegmentLengthTopologyConnector50-ohmcoax(thick)500metersBus100metersStarStarPoint-to-PointEIA/TIACat3,4,5UTP2pairEIA/TIACat5UTP2pair62.5/125micronmulti-modefiberAUIISO8877(RJ-45)Duplexmedia-interfaceconnector(MIC)STISO8877(RJ-45)400meters100metersIEEE802.3a802.3i802.3u802.3u以太網(wǎng)技術(shù)和以太網(wǎng)交換第3頁6.2吉比特和10G比特以太網(wǎng)1000Base-T1000Base-LX1000Base-SX10GBase-S/L/EMediaMaximumWorkLengthIEEEcodingCat5e/6

UTP4pair100meters802.3ab550meters62.5/50/10fiber8B1Q44D-PAM58B/10BNRZ5kmeters62.5/50/10fiber62.5/50/10fiber2-30kmeters802.3z802.3z802.3ae8B/10BNRZ8B/10B64B/66Betc.以太網(wǎng)技術(shù)和以太網(wǎng)交換第4頁6.3以太網(wǎng)交換技術(shù)1、交換機原理 經(jīng)過端口學(xué)習(xí)MAC地址 建立MAC地址表 將接收幀經(jīng)過過濾處理后轉(zhuǎn)發(fā)以太網(wǎng)技術(shù)和以太網(wǎng)交換第5頁交換機怎樣學(xué)習(xí)主機位置開始交換機MAC地址表是空MAC地址表0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3ABCD以太網(wǎng)技術(shù)和以太網(wǎng)交換第6頁交換機怎樣學(xué)習(xí)主機位置工作站A向工作站C發(fā)送數(shù)據(jù)幀交換機將E0端口和幀源地址即工作站AMAC地址寫入表中因為不知道工作站C在何處，所以向其它端口復(fù)制轉(zhuǎn)發(fā)（又稱泛射）MACaddresstable0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0:0260.8c01.1111E0E1E2E3DCBA以太網(wǎng)技術(shù)和以太網(wǎng)交換第7頁交換機怎樣學(xué)習(xí)主機位置StationDsendsaframetostationCSwitchcachesstationDMACaddresstoportE3bylearningthesourceAddressofdataframesTheframefromstationDtostationCisfloodedouttoallportsexceptportE3(unknownunicastsareflooded)MACaddresstable0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0:0260.8c01.1111E3:0260.8c01.4444E0E1E2E3DCAB以太網(wǎng)技術(shù)和以太網(wǎng)交換第8頁交換機怎樣過濾數(shù)據(jù)幀StationAsendsaframetostationCDestinationisknown,frameisnotfloodedE0:0260.8c01.1111E2:0260.8c01.2222E1:0260.8c01.3333E3:0260.8c01.44440260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3XXDCABMACaddresstable以太網(wǎng)技術(shù)和以太網(wǎng)交換第9頁廣播和多播幀StationDsendsabroadcastormulticastframeBroadcastandmulticastframesarefloodedtoallportsotherthantheoriginatingport0260.8c01.11110260.8c01.22220260.8c01.33330260.8c01.4444E0E1E2E3DCABE0:0260.8c01.1111E2:0260.8c01.2222E1:0260.8c01.3333E3:0260.8c01.4444MACaddresstable以太網(wǎng)技術(shù)和以太網(wǎng)交換第10頁6.3以太網(wǎng)交換技術(shù)2、switchingmode

store-and-forward

cut-through

fragment-free以太網(wǎng)技術(shù)和以太網(wǎng)交換第11頁6.3以太網(wǎng)交換技術(shù)多個連接，產(chǎn)生環(huán)路，易發(fā)生廣播風(fēng)暴。處理方案：STP生成樹協(xié)議，防止環(huán)路。3、廣播風(fēng)暴（BroadcastStorms）

以太網(wǎng)幀無休止循環(huán)復(fù)制，造成網(wǎng)絡(luò)擁塞、癱瘓。以太網(wǎng)技術(shù)和以太網(wǎng)交換第12頁Solution:Spanning-TreeProtocolProvidesaloopfreeredundantnetworktopologyby

placingcertainportsintheblockingstateBlock阻塞x以太網(wǎng)技術(shù)和以太網(wǎng)交換第13頁6.4STP生成樹協(xié)議1、STP（SpanningTreeProtocol）由規(guī)范IEEE802.1D要求，是指經(jīng)過生成樹算法，暫時切斷全部冗余連接，使網(wǎng)絡(luò)拓撲生成一個樹結(jié)構(gòu)，消除網(wǎng)絡(luò)循環(huán)，即確保從樹一點到其它任何一點只有一條路徑。STP使用一個稱為網(wǎng)橋協(xié)議數(shù)據(jù)單元BPDU（bridgeprotocoldataunit），它攜帶一些必要信息在整個網(wǎng)絡(luò)中進行多目廣播，經(jīng)過BPDUs信息，完成生成樹。

以太網(wǎng)技術(shù)和以太網(wǎng)交換第14頁2、BPDU

字節(jié)數(shù)目字段2協(xié)議標(biāo)識1版本1消息類型1保留8根ID4到根開銷8網(wǎng)橋ID2端口ID2消息年紀(jì)2最大年紀(jì)2呼叫時間2轉(zhuǎn)發(fā)延遲以太網(wǎng)技術(shù)和以太網(wǎng)交換第15頁3、生成樹過程

全部連接網(wǎng)橋經(jīng)過多播發(fā)送BPDUs，通告自己網(wǎng)橋ID，找到含有最低網(wǎng)橋ID網(wǎng)橋，并選舉這個網(wǎng)橋為根網(wǎng)橋（rootbridge），即“樹干”

計算非根網(wǎng)橋到根網(wǎng)橋路徑開銷（cost），選擇與根網(wǎng)橋連接含有最低開銷端口為根端口（rootport）

選擇其它網(wǎng)橋到根網(wǎng)橋含有最低路徑開銷端口為指定端口（designatedport），該網(wǎng)橋為指定網(wǎng)橋（designatedbridge），其它與根網(wǎng)橋相連端口為非指定端口（Nondesignatedport）

設(shè)置根端口、指定端口轉(zhuǎn)發(fā)數(shù)據(jù)（forwarding)，非指定端口阻塞(blocking)。以太網(wǎng)技術(shù)和以太網(wǎng)交換第16頁4、端口狀態(tài)阻塞（blocking）偵聽（listening）學(xué)習(xí)（learning）轉(zhuǎn)發(fā)（forwarding）禁用（deny）以太網(wǎng)技術(shù)和以太網(wǎng)交換第17頁阻塞和轉(zhuǎn)發(fā)阻塞（blocking）端口并沒有被禁止（deny），只是不轉(zhuǎn)發(fā)數(shù)據(jù)，但能接收STP呼入幀，一旦網(wǎng)絡(luò)拓撲發(fā)生改變，比如轉(zhuǎn)發(fā)數(shù)據(jù)端口或線路失效，阻塞端口很快轉(zhuǎn)換為轉(zhuǎn)發(fā)（forwarding）狀態(tài)，使網(wǎng)絡(luò)連通，繼續(xù)轉(zhuǎn)發(fā)數(shù)據(jù)，這也是冗余備份（redundancy）基本原理，我們也稱熱備份。阻塞端口經(jīng)過偵聽、學(xué)習(xí)兩個狀態(tài)后，變?yōu)檗D(zhuǎn)發(fā)狀態(tài)，網(wǎng)絡(luò)從斷開到重新連通，這段時間稱為網(wǎng)絡(luò)收斂（convergence），顯然這個收斂時間越小越好。以太網(wǎng)技術(shù)和以太網(wǎng)交換第18頁SwitchYDefaultpriority32768MAC0c0022222222SwitchXDefaultpriority32768MAC0c0011111111生成樹協(xié)議端口狀態(tài)RootbridgexPort0Port1Port0Port1100baseT10baseT

Designatedport(F)Rootport(F)Nondesignatedport(B)Designatedport(F)以太網(wǎng)技術(shù)和以太網(wǎng)交換第19頁SwitchYMAC0c0022222222Defaultpriority32768SwitchXMAC0c0011111111Defaultpriority32768Port0Port1Port0Port1SwitchZMac0c0011110000Defaultpriority32768Port0Canyoufigureout

:Whatistherootbridge?Whatarethedesignated,nondesignated,androotports?Whicharetheforwardingandblockingports?

100baseT100baseTSpanning-Tree:以太網(wǎng)技術(shù)和以太網(wǎng)交換第20頁SwitchYMAC0c0022222222Defaultpriority32768SwitchXMAC0c0011111111Defaultpriority32768Port0Port1Port0Port1SwitchZMac0c0011110000Defaultpriority32768Port0Canyoufigureout:Whatistherootbridge?Whatarethedesignated,nondesignated,androotparts?Whicharetheforwardingandblockingports?

100baseT100baseTSpanning-Tree:Designatedport(F)Rootport(F)Nondesignatedport(BLK)Designatedport(F)Rootport(F)以太網(wǎng)技術(shù)和以太網(wǎng)交換第21頁以太網(wǎng)技術(shù)和以太網(wǎng)交換第22頁以太網(wǎng)技術(shù)和以太網(wǎng)交換第23頁6.5局域網(wǎng)擴展技術(shù)LAN節(jié)點數(shù)目過多會引發(fā)網(wǎng)絡(luò)擁塞。比如：塞車以太網(wǎng)技術(shù)和以太網(wǎng)交換第24頁1、VLAN技術(shù)Segmentation

網(wǎng)段劃分Flexibility

擴展性Security 安全性3rdfloor2ndfloor1stfloorSALESHRENGAVLAN=Abroadcastdomain=Logicalnetwork(subnet)以太網(wǎng)技術(shù)和以太網(wǎng)交換第25頁VLAN虛擬局域網(wǎng)技術(shù)SwitchAGreenVLANBlackVLANRedVLANSwitchBGreenVLANBlackVLANRedVLAN

Trunk每個邏輯VLAN像一個獨立物理橋各VLAN能夠橫跨多個交換機Trunks管道為多個VLAN運載交通信息

FastEthernet以太網(wǎng)技術(shù)和以太網(wǎng)交換第26頁2、Trunk管道協(xié)議使用協(xié)議：IEEE802.1QISL(Cisco專用）配置：干線連接兩端。VLANTagstrippedbyforwardingportVLANTagaddedbyincomingportTrunk以太網(wǎng)技術(shù)和以太網(wǎng)交換第27頁3、VLAN間通信使用三層設(shè)備。如，多層交換機、路由器。以太網(wǎng)技術(shù)和以太網(wǎng)交換第28頁6.6用PowerPoint繪制網(wǎng)絡(luò)拓撲圖介紹校園網(wǎng)以太網(wǎng)技術(shù)和以太網(wǎng)交換第29頁C3550-12G中心管理機房(圖書館)CERNETInternet市內(nèi)?？偛繄D示說明1000M100M撥號訪問綜合樓1綜合教學(xué)大樓2學(xué)生宿舍個樓（1-7宿舍）大連理工大學(xué)城市學(xué)院校園網(wǎng)網(wǎng)絡(luò)拓撲圖數(shù)據(jù)庫服務(wù)器文件服務(wù)器認(rèn)證網(wǎng)管100M1000M10/100M多媒體教室