計(jì)算機(jī)網(wǎng)絡(luò)專業(yè)英語(yǔ) 課件全套 Lesson 1-18 Overview of Computer Network - OSI Reference Model and TCPIP

L1-1

Lesson1OverviewofComputerNetworks

Text1TheDefinitionofComputerNetwork要點(diǎn)keyPoints：詞匯現(xiàn)象網(wǎng)絡(luò)網(wǎng)絡(luò)設(shè)備、資源連接、鏈接和節(jié)點(diǎn)通信和通訊Computernetworkisalinkingofthenetworkdevicesandindependentcomputerswitheachothertoprovidedatacommunicationsandsharenetworkresourcessuchasprinter,scanner,modem,CD/DVDandinternetaccess.Today,nobusinesscanworkeffectivelywithoutthedatacommunicationswithintheorganization.名詞化合成詞專業(yè)詞匯縮略詞名詞連用名詞連用名詞連用名詞連用名詞連用借用詞派生詞派生詞派生詞network的語(yǔ)義很廣，包括其他的網(wǎng)絡(luò)和網(wǎng)狀物，但一般都是指計(jì)算機(jī)網(wǎng)絡(luò)。network是技術(shù)術(shù)語(yǔ)，也是由net（網(wǎng)）和work（作品）構(gòu)成的合成詞，net泛指一切網(wǎng)狀的事物。技術(shù)文獻(xiàn)中的技術(shù)術(shù)語(yǔ)一般只出現(xiàn)在本專業(yè)領(lǐng)域，而借用詞匯主要出現(xiàn)在非專業(yè)領(lǐng)域，例如和network語(yǔ)義相近的詞匯有g(shù)rid和mesh，指網(wǎng)眼、網(wǎng)格（小、密、整齊），grid在物聯(lián)網(wǎng)的文獻(xiàn)中會(huì)使用到。網(wǎng)絡(luò)network一般都是指計(jì)算機(jī)網(wǎng)絡(luò)computernetwork和network語(yǔ)義相近的詞匯有g(shù)rid和mesh網(wǎng)絡(luò)設(shè)備、資源Computernetworkisalinkingofthenetworkdevicesandindependentcomputerswitheachothertoprovidedatacommunicationsandsharenetworkresourcessuchasprinter,scanner,modem,CD/DVDandinternetaccess.Today,nobusinesscanworkeffectivelywithoutthedatacommunicationswithintheorganization.連接、鏈接和節(jié)點(diǎn)連接（V）（動(dòng)詞）

connect、link鏈接（動(dòng)詞）link“連接”的動(dòng)作（名詞）connecting、linking具體的“連接”物（小）（名詞）link、connector“連接”關(guān)系、連接物（大）（名詞）connection、linkage連接性（名詞）：connectivityAttach（附著），有主從關(guān)系，例如：attachaprogramfilestothee-mail.Join加入，連接Relate聯(lián)系例如：Shewasmyonlylinkwiththepast.名詞化通信和通訊communicate/communicationtelecommunication（電訊、電信）ChinaTelecom（中國(guó)電信）信息：message和informationIgotamessageyouweretryingtoreachme.或者someinformationapieceofinformationData和signal數(shù)據(jù)和信號(hào)Signal物理信號(hào)、data數(shù)據(jù)、information信息、knowledge知識(shí)，intelligence智力、wisdom智慧code（代碼、編碼）要點(diǎn)：詞匯現(xiàn)象網(wǎng)絡(luò)網(wǎng)絡(luò)設(shè)備資源連接、鏈接和節(jié)點(diǎn)通信和通訊L1-2

Lesson1OverviewofComputerNetworks

Text2PhysicalandLogicalLayoutofComputerNetworks要點(diǎn)KeyPoints：詞匯：設(shè)計(jì)邏輯的和物理的如何表示“頻度”詞匯：線、路徑、通道如何解釋和描述事物詞匯：拓?fù)?、布局Anetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.設(shè)計(jì)designdevise物理的和邏輯的physics/physical和logic/logicalAnetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.如何表示“頻度”Anetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.common、usual、normal、regular、ordinary、general和generic共同的常見(jiàn)的通常的正常的定期的經(jīng)常的普通的平常的一般的通常的reg-統(tǒng)治,規(guī)則詞根ordin表“秩序”詞根gen,生育，詞源同generate.即同種類的線、路徑、通道path、cable、wire、cord、line、channel、backbone和trunkAnetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.物理上的“路徑”和邏輯上的“軌跡”如何解釋和描述事物Anetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.isreferredtoasAmeansB或ThemeaningofAisB.forexample/instance、suchas，拉丁語(yǔ)的e.g.，用舉例的方法來(lái)說(shuō)明拓?fù)洹⒉季?shapeandlocationAnetworkcanbedesignedbydifferent

layoutsknownastopologies.Physicaltopologyisthephysicallayoutofthenetwork,whichdefineshowthecablesarearrangedandhowthecomputersareconnected.Logicaltopologyreferstothenatureofthepathsthesignalsfollowfromnodetonode.Inmanyinstances,thelogicaltopologyisthesameasthephysicaltopology.Butthisisnotalwaysthecase.Thecommontopologiesincludebus,star,tree,mesh,hybridandring,asshowninFigure1-1.要點(diǎn)KeyPoints：詞匯：設(shè)計(jì)邏輯的和物理的如何表示“頻度”詞匯：線、路徑、通道如何解釋和描述事物詞匯：拓?fù)浜筒季諰1-2

Lesson1OverviewofComputerNetworks

Text2PhysicalandLogicalLayoutofComputerNetworksL1-3

Lesson1OverviewofComputerNetworks

Text3BusTopology要點(diǎn)KeyPoints：詞匯：終端詞匯：傳輸詞匯：接收、反射、吸收、確認(rèn)詞匯：Common、commonly、normally理解和掌握：同步、同時(shí)理解和掌握：虛擬的、真實(shí)的、實(shí)際的表示原因的句型終端Inbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.end-point\endpointterminal：終端（設(shè)備）、航站樓terminator：終端器，終結(jié)者termination：終止傳輸Inbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.Transfer轉(zhuǎn)讓；轉(zhuǎn)接；移交；轉(zhuǎn)移（地方）；（使）換乘；轉(zhuǎn)存，轉(zhuǎn)錄；調(diào)動(dòng)（工作）；傳染，傳播；使（運(yùn)動(dòng)員）轉(zhuǎn)隊(duì)；把（錢）轉(zhuǎn)到另一賬戶，機(jī)構(gòu)上。動(dòng)，名接收、反射、吸收、確認(rèn)。。。。Inbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.accept：確認(rèn)（接收）主動(dòng)或自愿地接受,經(jīng)過(guò)考慮后同意接受。reject拒絕receive：僅僅指接到或收到這一事實(shí)Reflect反射（反方向折回），flexible靈活的（容易折的）Inflect彎曲，改變，Common、commonly、normallyInbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.Inbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.同步、同時(shí)和synchronous/synchronized（同步的），詞意完全不同virtual所表達(dá)的“事實(shí)上的”是指“看起來(lái)，但其實(shí)不是，并未在名義上或正式上獲得承認(rèn)”虛擬的、真實(shí)的、實(shí)際的Inbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignaltopreventthesignalfrombeingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.virtual（虛擬的；實(shí)質(zhì)上的，事實(shí)上的）factual，infact（事實(shí)上，實(shí)際上）虛擬現(xiàn)實(shí)：virtualreality反義詞：real實(shí)際的；真實(shí)的；實(shí)在的actual（真實(shí)的，實(shí)際的）近義詞：valid，available，practical，effective，telling，significantInbustopology,allofthenodesofthenetworkareconnectedtoacommontransmissionmediumwhichhasexactlytwoendpoints(thisisthe“bus”,whichisalsocommonlyreferredtoasthebackboneortrunk).Alldatathatistransmittedbetweennodesinthenetworkistransmittedoverthiscommontransmissionmediumandisabletobereceivedbyallnodesinthenetworkvirtuallysimultaneously.Thetwoendpointsofthecommontransmissionmediumarenormallyterminatedwithadevicecalledaterminatorthatexhibitsthecharacteristicimpedanceofthetransmissionmediumandwhichdissipatesorabsorbstheenergythatremainsinthesignal

topreventthesignalfrom

beingreflectedandpropagatedbackontothetransmissionmediumintheoppositedirection,whichwouldotherwisecauseinterferenceanddegradationofthesignalsonthetransmissionmedium.表示原因要點(diǎn)KeyPoints：詞匯：終端詞匯：傳輸詞匯：接收、反射、吸收、確認(rèn)詞匯：Common、commonly、normally理解和掌握：同步、同時(shí)理解和掌握：虛擬的、真實(shí)的、實(shí)際的表示原因的句型L1-4

Lesson1OverviewofComputerNetworks

Text4StarTopology要點(diǎn)KeyPoints：P2P描述行為方式（）-

e.g.“”-basedconverge、collection有源設(shè)備P2Ppoint-to-point點(diǎn)到點(diǎn)，是一個(gè)復(fù)合詞，該詞常根據(jù)諧音形象地書(shū)寫為P2P，這時(shí)又往往帶來(lái)了歧義。peertopeer/peer-to-peerpersontoperson/person-to-personInstartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.unicast單播fashion式樣、方式還有一些類似的詞匯，例如：表示“模式”的：mode、pattern。表示“方式、方法”的：way、method、manner描述行為方式Instartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.（）-

e.g.“”Instartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)

–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.破折號(hào)dash和連字號(hào)Hyphen在英文中長(zhǎng)得一樣，但是是不同語(yǔ)義的符號(hào)。Ethernet-based（基于以太網(wǎng)的）表示建立在以太網(wǎng)基礎(chǔ)上 -basedInstartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.localareanetworkwhichisbasedonEthernetconverge、collectionInstartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.collection/collect收集convergence/converge聚集（gather）congest擁塞Integrade集成有源設(shè)備Instartopology,eachofthenodesofthenetworkisconnectedtoacentralnodewithapoint-to-pointlinkina“hub”and“spoke”fashion,thecentralnodebeingthe“hub”andthenodesthatareattachedtothecentralnodebeingthe“spokes”(e.g.,acollectionofpoint-to-pointlinksfromtheperipheralnodesthatconvergeatacentralnode)–alldatathatistransmittedbetweennodesinthenetworkistransmittedtothiscentralnode,whichisusuallysometypeofdevicethatthenretransmitsthedatatosomeoralloftheothernodesinthenetwork,althoughthecentralnodemayalsobeasimplecommonconnectionpointwithoutanyactivedevicetorepeatthesignals.StartopologyisthemostcommontopologyinEthernet-basedlocalareanetwork.active好動(dòng)的；積極主動(dòng)的有（電）源的passive消極的，被動(dòng)的無(wú)（電）源的passPassiveactiveNegativepositive要點(diǎn)KeyPoints：P2P描述行為方式（）-

e.g.“”-basedconverge、collection有源設(shè)備L1-4

Lesson1OverviewofComputerNetworks

Text4StarTopologyL1-5

Lesson1OverviewofComputerNetworks

Text5RingTopology要點(diǎn)KeyPoints：流動(dòng)方向以……方式形成circular、circularity、cycled、cycle、ring和loop，網(wǎng)絡(luò)中的“回路”敘述順序Inringtopology,eachofthenodesofthenetworkisconnectedtotwoothernodesinthenetworkandwiththefirstandlastnodesbeingconnectedtoeachother,formingaring–alldatathatistransmittedbetweennodesinthenetworktravelsfromonenodetothenextnodeinacircularmannerandthedatagenerallyflows

inasingledirectiononly.流動(dòng)、方向、以……方式、形成單向：singledirection

unidirection雙向：bidirection多向：multidirection反向：？manner：態(tài)度、舉止、習(xí)慣fashion：（外表）形式form：（關(guān)系、習(xí)慣或想法）形成、構(gòu)成constitute、makeupcircular和cycled都是“循環(huán)的”，分別從“圓的形狀”和“時(shí)間的周期性”引申而來(lái)。circle/?s??kl圓（形、物），circuit電路，IC：integratedcircuitcircularity表示（抽象的）圓的形狀cycle/?sa?kl/

（時(shí)間上的）周期bicycle自行車ring和loop都是“環(huán)狀物”，loop還可以指環(huán)路、回路。Inringtopology,eachofthenodesofthenetworkisconnectedtotwoothernodesinthenetworkandwiththefirstandlastnodesbeingconnectedtoeachother,formingaring–alldatathatistransmittedbetweennodesinthenetworktravelsfromonenodetothenextnodeinacircularmannerandthedatagenerallyflowsinasingledirectiononly.戒指；環(huán)狀物；圓形Inringtopology,eachofthenodesofthenetworkisconnectedtotwoothernodesinthenetworkandwiththefirstandlastnodesbeingconnectedtoeachother,formingaring–alldatathatistransmittedbetweennodesinthenetworktravelsfromonenodetothenextnodeinacircularmannerandthedatagenerallyflowsinasingledirectiononly.thelast最后的Last+過(guò)去時(shí)語(yǔ)句，上一次previous

thenext的反義詞，前面一個(gè)該如何表達(dá)？敘述順序要點(diǎn)KeyPoints：流動(dòng)方向以……方式形成circular、circularity、cycled、cycle、ring和loop，網(wǎng)絡(luò)中的“回路”敘述順序L1-5

Lesson1OverviewofComputerNetworks

Text5RingTopologyL1-6

Lesson1OverviewofComputerNetworks

Text6Mesh，Tree(orHierarchical)andHybridTopology要點(diǎn)KeyPoints：工程上的/花費(fèi)/性能/性價(jià)比special/specific/fixedi.e.分支對(duì)稱描述層次結(jié)構(gòu)becomposedof，inter工程上的/花費(fèi)/性能/性價(jià)比Inmeshtopology,eachofthenodesofthenetworkisconnectedtoeachoftheothernodesinthenetworkwithapoint-to-pointlink–thismakesitpossiblefordatatobesimultaneouslytransmittedfromanysinglenodetoalloftheothernodes.Thephysicalfullyconnectedmeshtopologyisgenerallytoocostlyandcomplexforpracticalnetworks,althoughthetopologyisusedwhenthereareonlyasmallnumberofnodestobeinterconnected.cost（代價(jià)、花費(fèi)）（n.v.）相對(duì)應(yīng)的是performance（性能）costperformance（性價(jià)比）是IT行業(yè)非常關(guān)注的一個(gè)技術(shù)指標(biāo)。costly和expensive同義。physical（物理上的）對(duì)應(yīng)logical（邏輯上的）

practical（工程實(shí)踐上的）對(duì)應(yīng)theoretical（理論上的）Intreetopology,acentral“root”node(thetoplevelofthehierarchy)isconnectedtooneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thesecondlevel)withapoint-to-pointlinkbetweeneachofthesecondlevelnodesandthetoplevelcentral“root”node,whileeachofthesecondlevelnodesthatareconnectedtothetoplevelcentral“root”nodewillalsohaveoneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thethirdlevel)connectedtoit,alsowithapoint-to-pointlink,thetoplevelcentral“root”nodebeingtheonlynodethathasnoothernodeaboveitinthehierarchy–thehierarchyofthetreeissymmetrical,eachnodeinthenetworkhavingaspecificfixednumber“f”,beingreferredtoasthe“branchingfactor”ofthehierarchicaltree.specific特定的。強(qiáng)調(diào)“明確、具體”specification規(guī)格、說(shuō)明書(shū)special特別的。強(qiáng)調(diào)“與其他不同”particular特定的，詳盡的fixed固定不變的反義詞：flexible靈活的special/specific/fixed，i.e.,對(duì)稱的，分支分支（branch）對(duì)應(yīng)的是主干（backbone、trunk）i.e.（即、也就是）源拉丁語(yǔ)idest[id'est]Intreetopology,acentral“root”node(thetoplevelofthehierarchy)isconnectedtooneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thesecondlevel)withapoint-to-pointlinkbetweeneachofthesecondlevelnodesandthetoplevelcentral“root”node,whileeachofthesecondlevelnodesthatareconnectedtothetoplevelcentral“root”nodewillalsohaveoneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thethirdlevel)connectedtoit,alsowith

apoint-to-pointlink,thetoplevelcentral“root”nodebeingtheonlynodethathasnoothernodeaboveitinthehierarchy–thehierarchyofthetreeissymmetrical,eachnodeinthenetworkhavingaspecificfixednumber“f”,beingreferredtoasthe“branchingfactor”ofthehierarchicaltree.描述層次結(jié)構(gòu)定語(yǔ)：that，括弧狀語(yǔ)：while，with、破擇號(hào)，ingHybridtopologyisatypeofnetworktopologythatiscomposedofoneormoreinterconnectionsoftwoormorenetworksthatarebasedupondifferentphysicaltopologiesmentionedabove.becomposedof，inter，typeL0-7詞匯學(xué)習(xí)示例2L1-7

Lesson1OverviewofComputerNetworks

Text7PhysicalandLogicalLayoutofComputerNetworks要點(diǎn)KeyPoints：從英語(yǔ)的角度理解專業(yè)詞匯Level和layerThetransmissionmediausedtolinkdevicestoformacomputernetworkincludeelectricalcable(UTP/STPcables,telephonewires,coaxial

cables,andpowerlines),fiber

opticsandradiowaves.IntheOSImodel,thesearedefinedatlayers1and2–thephysicallayerandthedatalinklayer.Apartfromanyphysicaltransmissionmedium,networkscompriseadditionalbasicdevices,suchasnetworkinterfacecontrollers(NICs),repeaters,hubs,transceivers,bridges,switches,routers,modems,andfirewalls.Repeater：重復(fù)器，中繼器Transceiver：收發(fā)器receiver電話機(jī)的聽(tīng)筒等Bridge：網(wǎng)橋

Switch：（鐵道的）道岔switcherRouter:route路線fiberoptics/opticalfiberelectricalcable：與電有關(guān)的纜，電纜electriccable？Radiowave：無(wú)線電波從英語(yǔ)的角度理解專業(yè)詞匯Thetransmissionmediausedtolinkdevicestoformacomputernetworkincludeelectricalcable(UTP/STPcables,telephonewires,coaxialcables,andpowerlines),fiberopticsandradiowaves.IntheOSImodel,thesearedefinedatlayers1and2–thephysicallayerandthedatalinklayer.Apartfromanyphysicaltransmissionmedium,networkscompriseadditionalbasicdevices,suchasnetworkinterfacecontrollers(NICs),repeaters,hubs,transceivers,bridges,switches,routers,modems,andfirewalls.Intreetopology,acentral“root”node(thetoplevelofthehierarchy)isconnectedtooneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thesecondlevel)withapoint-to-pointlinkbetweeneachofthesecondlevelnodesandthetoplevelcentral“root”node,whileeachofthesecondlevelnodesthatareconnectedtothetoplevelcentral“root”nodewillalsohaveoneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thethirdlevel)connectedtoit,alsowithapoint-to-pointlink,thetoplevelcentral“root”nodebeingtheonlynodethathasnoothernodeaboveitinthehierarchy–thehierarchyofthetreeissymmetrical,eachnodeinthenetworkhavingaspecificfixednumber“f”,beingreferredtoasthe“branchingfactor”ofthehierarchicaltree.Level和layer鋪設(shè)（強(qiáng)調(diào)層本身的內(nèi)容）水平（強(qiáng)調(diào)層之間的順序）L1-8

Lesson1OverviewofComputerNetworks

Text8Protocols要點(diǎn)KeyPoints：標(biāo)準(zhǔn)和協(xié)議Common和commonSuite和stackInternet和internetOneofthesespecializedstandardsandagree-upwaysisknownasprotocols.TCP/IPistheprotocolsuitethatcontainsmultiplecommunicationprotocolssuchasTCP,IP,SMTP,FTP,DHCP,LDAP,PPP,Telnetandmanyothers.TCP/IPworkstogetheranditisthemostcommoncommunicationprotocolforLAN,WANandInternet.ThecommunicationsontheInternetarebasedontheIPaddress,whichisapartoftheTCP/IPstacks.NocomputersontheInternetorintheLAN/MAN/WANcancommunicatewithoutauniqueIPaddress.Internetworkisatypeofcomputernetworkthatconnectsthetwoormoredifferentnetworksviaacommonroutingtechnology,

usingrouters.Therearethreemaintypesofinternetworks,i.e.,Intranet,ExtranetandInternet.protocol禮儀，<正式>國(guó)際議定書(shū)，網(wǎng)絡(luò)協(xié)議，agreementsuite套房,（程序）組；一套產(chǎn)品Stack(整齊的）一堆；堆棧；protocolstack

協(xié)議棧標(biāo)準(zhǔn)和協(xié)議，common和common，suite和stackOneofthesespecializedstandardsandagree-upwaysisknownasprotocols.TCP/IPistheprotocolsuitethatcontainsmultiplecommunicationprotocolssuchasTCP,IP,SMTP,FTP,DHCP,LDAP,PPP,Telnetandmanyothers.TCP/IPworkstogetheranditisthemostcommoncommunicationprotocolforLAN,WANandInternet.ThecommunicationsontheIn