1-6 每一层使用的设备、ARP和数据传输过程

©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-1BuildingaSimpleNetworkExploringthePacketDeliveryProcess©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-2Layer1DevicesLayer1providesthephysicalmediaanditsencoding.Examples:–Ethernet–Serial–Repeater–PhysicalinterfaceoftheNIC©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-3Layer2DevicesLayer2devicesprovideaninterfacewiththephysicalmedia.Examples:–NIC–Bridge–Switch©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-4Layer2AddressingMACaddressAssignedtoenddevices©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-5Layer3DevicesandTheirFunctionThenetworklayerprovidesconnectivityandpathselectionbetweentwohostsystems.Inthehost,thisisthepathbetweenthedatalinklayerandtheupperlayersoftheNOS.Intherouter,itistheactualpathacrossthenetwork.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-6Layer3AddressingEachNOShasitsownLayer3addressformat.OSIusesanNSAP.TCP/IPusesIP.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-7ARP©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-8ARPTable©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-9Host-to-HostPacketDelivery(1of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-10Host-to-HostPacketDelivery(2of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-11Host-to-HostPacketDelivery(3of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-12Host-to-HostPacketDelivery(4of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-13Host-to-HostPacketDelivery(5of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-14Host-to-HostPacketDelivery(6of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-15Host-to-HostPacketDelivery(7of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-16Host-to-HostPacketDelivery(8of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-17Host-to-HostPacketDelivery(9of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-18Host-to-HostPacketDelivery(10of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-19Host-to-HostPacketDelivery(11of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-20Host-to-HostPacketDelivery(12of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-21Host-to-HostPacketDelivery(13of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-22Host-to-HostPacketDelivery(14of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-23Host-to-HostPacketDelivery(15of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-24Host-to-HostPacketDelivery(16of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-25Host-to-HostPacketDelivery(17of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-26Host-to-HostPacketDelivery(18of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-27Host-to-HostPacketDelivery(19of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-28Host-to-HostPacketDelivery(20of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-29Host-to-HostPacketDelivery(21of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-30Host-to-HostPacketDelivery(22of22)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-31DefaultGateway©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-32Host-BasedTools:ping©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-34Host-BasedTools:Table©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-35Host-BasedTools:tracert©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-37SummaryLayer1providesthephysicalmediaanditsencoding.Layer2devicesprovideaninterfacewiththephysicalmedia.Layer2addressesareMACaddresses.Thenetworklayerprovidesconnectivityandpathselectionbetweentwohostsystems.Layer3addressesareIPaddresses.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-38Summary(Cont.)Beforeahostcansenddatatoanotherhost,itmusthavetheMACaddressofthathost.IftheMACaddressisnotknown,ARPisusedtomapLayer2toLayer3.ReliablecommunicationrequiresaTCPsession.Datasentmustbeacknowledged.Ifhostsareondifferentsegments,adefaultgatewayisneeded.Severalhost-basedtoolsareavailabletocheckconnectivitybetweenhosts:–ping–tracert–arp©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-39