Strato di interfaccia di rete

Introductio

ThenetworkinterfacelayerisnotactuallypartoftheInternetprotocolsuite,butitisamethodfordatapacketstobetransmittedfromthenetworklayerofonedevicetothenetworklayerofanotherdevice.Thisprocesscanbecontrolledinthesoftwaredriverofthenetworkcard,orinthefirmwareordedicatedchip.Thiswillcompletesomedatalinkfunctionssuchasaddingaheadertopreparefortransmission,andactuallytransmittingthroughthephysicalmedium.Attheotherend,thelinklayerwillcompletethedataframereception,removetheheaderandpassthereceivedpackettothenetworklayer.

Network interface layer

However,thelinklayerisnotoftenthissimple.Itmayalsobeavirtualprivatenetwork(VPN)ortunnel,wherepacketsfromthenetworklayeraresentusingthetunnelprotocolandother(orthesame)protocolsuiteinsteadofbeingsenttothephysicalinterface.VPNsandtunnelsareusuallypre-built,andtheyhavesomespecialfeaturesthatarenotdirectlysenttothephysicalinterface(forexample,itcanencryptdatapassingthroughit).Sincethelink"layer"isnowacompletenetwork,therecursiveuseofthisprotocolsuitemaycauseconfusion.Butitisanexcellentwaytoimplementcommoncomplexfunctions.(Althoughyouneedtopayattentiontopreventapacketthathasbeenencapsulatedandsentthroughthetunneltobeencapsulatedandsentagain).

Relatedinformation

ThenetworkinterfacelayercorrespondstothephysicallayeranddatalinklayerintheOSIreferencemodel.ThenetworkinterfacelayeristheinterfacebetweenTCP/IPandvariousLANsorWANs.

Thenetworkinterfacelayerencapsulatestheupper-layerIPdatagramintoaframeatthesendingendandsendsittothenetwork;whenthedataframereachesthereceivingendthroughthenetwork,thenetworkinterfacelayerofthenodedecapsulatesthedataframe.AndchecktheMACaddresscontainedintheframe.IftheaddressistheMACaddressofthemachineorthebroadcastaddress,itwillbeuploadedtothenetworklayer,otherwisetheframewillbediscarded.

Whenaseriallineisusedtoconnectthehostandthenetwork,ortoconnectthenetworkandthenetwork,forexample,thehostconnectstotheInternetthroughamodemandtelephoneline,youneedtoruntheSLIPorPPPprotocolatthenetworkinterfacelayer.

☆SLIP(SerialLineInternetProtocol)protocolprovidesasimplewaytoencapsulateIPdatagramsonserialcommunicationlines,allowinguserstoeasilyaccessTCP/IPnetworksthroughtelephonelinesandmodems.

☆PPP(PointtoPointProtocol)isaneffectivepoint-to-pointcommunicationprotocolthatsolvestheabove-mentionedproblemsofSLIP,thatis,itcansupportmultiplenetworklayerprotocols(suchasIP,IPX,etc.),SupportsdynamicallyallocatedIPaddresses;andacheckfieldissetinthePPPframe,soPPPhaserrorcheckingcapabilitiesonthenetworkinterfacelayer.

Related Articles
TOP