通信外文翻译了解 TCPIP 寻址和子网配置基础知识Word下载.docx

通信外文翻译了解 TCPIP 寻址和子网配置基础知识Word下载.docx

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WhenyouconfiguretheTCP/IPprotocolonaMicrosoftWindowscomputer,anIPaddress,subnetmask,andusuallyadefaultgatewayarerequiredintheTCP/IPconfigurationsettings.

ToconfigureTCP/IPcorrectly,itisnecessarytounderstandhowTCP/IPnetworksareaddressedanddividedintonetworksandsubnetworks.ThisarticleisintendedasageneralintroductiontotheconceptsofIPnetworksandsubnetting.Aglossaryisincludedattheendofarticle.

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⏹MOREINFORMATION

ThesuccessofTCP/IPasthenetworkprotocoloftheInternetislargelybecauseofitsabilitytoconnecttogethernetworksofdifferentsizesandsystemsofdifferenttypes.Thesenetworksarearbitrarilydefinedintothreemainclasses（alongwithafewothers）thathavepredefinedsizes,eachofwhichcanbedividedintosmallersubnetworksbysystemadministrators.AsubnetmaskisusedtodivideanIPaddressintotwoparts.Onepartidentifiesthehost（computer）,theotherpartidentifiesthenetworktowhichitbelongs.TobetterunderstandhowIPaddressesandsubnetmaskswork,lookatanIP（InternetProtocol）addressandseehowitisorganized.

●IPaddresses:

Networksandhosts

AnIPaddressisa32-bitnumberthatuniquelyidentifiesahost（computerorotherdevice,suchasaprinterorrouter）onaTCP/IPnetwork.

IPaddressesarenormallyexpressedindotted-decimalformat,withfournumbersseparatedbyperiods,suchas192.168.123.132.Tounderstandhowsubnetmasksareusedtodistinguishbetweenhosts,networks,andsubnetworks,examineanIPaddressinbinarynotation.

Forexample,thedotted-decimalIPaddress192.168.123.132is（inbinarynotation）the32bitnumber110000000101000111101110000100.Thisnumbermaybehardtomakesenseof,sodivideitintofourpartsofeightbinarydigits.

Theseeightbitsectionsareknownasoctets.TheexampleIPaddress,then,becomes11000000.10101000.01111011.10000100.Thisnumberonlymakesalittlemoresense,soformostuses,convertthebinaryaddressintodotted-decimalformat（192.168.123.132）.Thedecimalnumbersseparatedbyperiodsaretheoctetsconvertedfrombinarytodecimalnotation.

ForaTCP/IPwideareanetwork（WAN）toworkefficientlyasacollectionofnetworks,theroutersthatpasspacketsofdatabetweennetworksdonotknowtheexactlocationofahostforwhichapacketofinformationisdestined.Routersonlyknowwhatnetworkthehostisamemberofanduseinformationstoredintheirroutetabletodeterminehowtogetthepackettothedestinationhost'

snetwork.Afterthepacketisdeliveredtothedestination'

snetwork,thepacketisdeliveredtotheappropriatehost.

Forthisprocesstowork,anIPaddresshastwoparts.ThefirstpartofanIPaddressisusedasanetworkaddress,thelastpartasahostaddress.Ifyoutaketheexample192.168.123.132anddivideitintothesetwopartsyougetthefollowing:

192.168.123.Network

.132Host

-or-

192.168.123.0-networkaddress.

0.0.0.132-hostaddress.

●Subnetmask

Theseconditem,whichisrequiredforTCP/IPtowork,isthesubnetmask.ThesubnetmaskisusedbytheTCP/IPprotocoltodeterminewhetherahostisonthelocalsubnetoronaremotenetwork.

InTCP/IP,thepartsoftheIPaddressthatareusedasthenetworkandhostaddressesarenotfixed,sothenetworkandhostaddressesabovecannotbedeterminedunlessyouhavemoreinformation.Thisinformationissuppliedinanother32-bitnumbercalledasubnetmask.Inthisexample,thesubnetmaskis255.255.255.0.Itisnotobviouswhatthisnumbermeansunlessyouknowthat255inbinarynotationequals11111111;

so,thesubnetmaskis:

11111111.11111111.11111111.0000000

LininguptheIPaddressandthesubnetmasktogether,thenetworkandhostportionsoftheaddresscanbeseparated:

11000000.10101000.01111011.10000100--IPaddress（192.168.123.132）

11111111.11111111.11111111.00000000--Subnetmask（255.255.255.0）

Thefirst24bits（thenumberofonesinthesubnetmask）areidentifiedasthenetworkaddress,withthelast8bits（thenumberofremainingzerosinthesubnetmask）identifiedasthehostaddress.Thisgivesyouthefollowing:

11000000.10101000.01111011.00000000--Networkaddress（192.168.123.0）

00000000.00000000.00000000.10000100--Hostaddress（000.000.000.132）

Sonowyouknow,forthisexampleusinga255.255.255.0subnetmask,thatthenetworkIDis192.168.123.0,andthehostaddressis0.0.0.132.Whenapacketarrivesonthe192.168.123.0subnet（fromthelocalsubnetoraremotenetwork）,andithasadestinationaddressof192.168.123.132,yourcomputerwillreceiveitfromthenetworkandprocessit.

Almostalldecimalsubnetmasksconverttobinarynumbersthatareallonesontheleftandallzerosontherigh