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1、中南民族大学毕业论文(设计)英文翻译材料学院:计算机科学学院专业：网络工程年级:2009学生姓名:学号:指导教师姓名:职称:讲师原文（RFC2178-OSPFVersion2）TheospfFloodingProcedureLinkStateUpdatepacketsprovidethemechanismforfloodingLSAs.ALinkStateUpdatepacketmaycontainseveraldistinctLSAs,andfloodseachLSAonehopfurtherfromitspointoforiginatio
2、n.Tomakethefloodingprocedurereliable,eachLSAmustbeacknowledgedseparately.AcknowledgmentsaretransmittedinLinkStateAcknowledgmentpackets.Manyseparateacknowledgmentscanalsobegroupedtogetherintoasinglepacket.ThefloodingprocedurestartswhenaLinkStateUpdatepackethasbeenreceived.Ma
3、nyconsistencycheckshavebeenmadeonthereceivedpacketbeforebeinghandedtothefloodingprocedure(seeSection8.2).Inparticular,theLinkStateUpdatepackethasbeenassociatedwithaparticularneighbor,andaparticulararea.IftheneighborisinalesserstatethanExchange,thepacketshouldbedroppedwithou
4、tfurtherprocessing.AlltypesofLSAs,otherthanAS-external-LSAs,areassociatedwithaspecificarea.However,LSAsdonotcontainanareafield.AnLSA’sareamustbededucedfromtheLinkStateUpdatepacketheader.ForeachLSAcontainedinaLinkStateUpdatepacket,thefollowingstepsaretaken:(1)ValidatetheLSA’
5、sLSchecksum.Ifthechecksumturnsouttobeinvalid,discardtheLSAandgetthenextonefromtheLinkStateUpdatepacket.(2)ExaminetheLSA’sLStype.IftheLStypeisunknown,discardtheLSAandgetthenextonefromtheLinkStateUpdatePacket.ThisspecificationdefinesLStypes1-5(seeSection4.3).(3)Elseifthisisan
6、AS-external-LSA(LStype=5),andtheareahasbeenconfiguredasastubarea,discardtheLSAandgetthenextonefromtheLinkStateUpdatePacket.AS-external-LSAsarenotfloodedinto/throughoutstubareas(seeSection3.6).(4)ElseiftheLSA’sLSageisequaltoMaxAge,andthereiscurrentlynoinstanceoftheLSAinthero
7、uter’slinkstatedatabase,andnoneofrouter’sneighborsareinstatesExchangeorLoading,thentakethefollowingactions:a)AcknowledgethereceiptoftheLSAbysendingaLinkStateAcknowledgmentpacketbacktothesendingneighbor(seeSection13.5),andb)DiscardtheLSAandexaminethenextLSA(ifany)listedinthe
8、LinkStateUpdatepacket.(5)Otherwise,findtheinstanceofthisLSAthatiscurrentlycontaine
