1、 1999,Cisco Systems,Inc.2-1Chapter 2Internetworking Concepts Overview 1999,Cisco Systems,IICND2-2ObjectivesOn completion of this chapter,you will be able to perform the following tasks:Describe how data traffic is exchanged between source and destination devices Identify the roles and functions of a
2、 hub,switch,and router,and where they best fit in the network Select the appropriate Cisco equipment for a given set of network requirements 1999,Cisco Systems,IICND2-3Defining Components of the NetworkMain OfficeBranch Office Home Office Mobile UsersInternetredundency 1999,Cisco Systems,IICND2-4Flo
3、or 2Floor 1Server FarmDefining the Components of a Network(cont.)Branch OfficeTelecommuterISDNRemoteCampus 1999,Cisco Systems,IICND2-5Network Structure Defined by Hierarchy Distribution LayerCore LayerAccessLayer 1999,Cisco Systems,IICND2-6Access Layer CharacteristicsEnd station entry point to the n
4、etworkAccess Layer 1999,Cisco Systems,IICND2-7Distribution Layer Characteristics Access Layer Aggregation Point Routes traffic Broadcast/Multicast Domains Media Translation Security Possible point for remote accessDistribution Layer 1999,Cisco Systems,IICND2-8Core Layer Characteristics Fast transpor
5、t to enterprise services No packet manipulationCore Layer 1999,Cisco Systems,IICND2-9OSI Model OverviewData Flow LayersTransport LayerData Link Network LayerPhysicalApplication(Upper)LayersSessionPresentationApplication注意注意OSI模型与网络三个层次的区别模型与网络三个层次的区别 1999,Cisco Systems,IICND2-10Keeping different app
6、lications data separateUser InterfaceHow data is presentedSpecial processing such as encryptionTelnetHTTPASCIIEBCDICJPEGOperating System/Application Access SchedulingTransport LayerData Link Network LayerPhysicalEXAMPLESSessionPresentationApplicationRole of Application Layers 1999,Cisco Systems,IICN
7、D2-11TCPUDPSPX802.3/802.2HDLCEIA/TIA-232V.35IPIPXPresentationApplicationSessionEXAMPLESRole of Data Flow Layers Reliable or unreliable delivery Error correction before retransmit Combines bits into bytes and bytes into frames Access to media using MAC address Error detection not correction Move bits
8、 between devices Specifies voltage,wire speed and pin-out cablesTransport Data LinkPhysical Network Provide logical addressing which routers use for path determination 1999,Cisco Systems,IICND2-12Encapsulating DataTransport Data LinkPhysical Network Upper Layer DataUpper Layer DataTCP HeaderDataIP H
9、eaderDataLLC Header0101110101001000010DataMAC HeaderPresentationApplicationSessionSegmentPacketBitsFramePDUFCSFCSProtocol data units 1999,Cisco Systems,IICND2-13Upper Layer DataDe-encapsulating DataLLC Hdr+IP+TCP+Upper Layer DataMAC HeaderIP+TCP+Upper Layer DataLLC HeaderTCP+Upper Layer DataIP Heade
10、rUpper Layer DataTCP Header0101110101001000010Transport Data LinkPhysical Network PresentationApplicationSession 1999,Cisco Systems,IICND2-14ApplicationPresentationSessionTransportNetworkData LinkPhysicalOSI ModelPDUFunctional ResponsibilitiesExamplesWritten Exercise:OSI Model 1999,Cisco Systems,IIC
11、ND2-15Physical Layer FunctionsDefines Media type Connector type Signaling typeEthernet802.3V.35PhysicalEIA/TIA-232 1999,Cisco Systems,IICND2-16Physical Layer:Ethernet/802.3HubHostsHost10Base2Thick Ethernet10Base5Thick Ethernet10BaseTTwisted Pair 1999,Cisco Systems,IICND2-17Hubs Operate at Physical l
12、ayerABCDPhysical All devices in the same collision domain All devices in the same broadcast domain Devices share the same bandwidth 1999,Cisco Systems,IICND2-18Hubs:One Collision Domain More end stations means more collisions CSMA/CD is used 1999,Cisco Systems,IICND2-19Data Link layer FunctionsDefin
13、es Physical source and destination addresses Higher layer protocol(Service Access Point)associated with frame Network topology Frame sequencing Flow control Connection-oriented or connectionlessData LinkPhysicalEIA/TIA-232v.35EthernetFrame RelayHDLC802.2802.3 1999,Cisco Systems,IICND2-20DataSource a
14、ddFCSLengthDest addVariable26640000.0C xx.xxxxVendor assignedIEEE assignedMAC Layer-802.3Data Link Layer Functions(cont.)PreambleEthernet II uses“Type”here and does not use 802.2.MAC Address8#Bytes 1999,Cisco Systems,IICND2-21DataDest SAPSource SAPDataSource addFCSLengthDest addVariable11802.2(SAP)M
15、AC Layer-802.3Data Link Layer Functions(cont.)Ctrl1 or 232PreambleDataDest SAPAASource SAPAAVariable11802.2(SNAP)Ctrl031 or 2OROUI IDType为为高层协议使用高层协议使用 1999,Cisco Systems,IICND2-22 Each segment has its own collision domain All segments are in the same broadcast domainData LinkSwitches and Bridges Op
16、erate at Data Link LayerOR123124 1999,Cisco Systems,IICND2-23Switches Each segment has its own collision domain Broadcasts are forwarded to all segmentsMemorySwitch 1999,Cisco Systems,IICND2-24Network Layer Functions Defines logical source and destination addresses associated with a specific protoco
17、l Defines paths through network Interconnects multiple data linksNetworkIP,IPXData LinkPhysicalEIA/TIA-232v.35EthernetFrame RelayHDLC802.2802.3 1999,Cisco Systems,IICND2-25DataSourceaddressDestination addressIPNetwork Layer Functions(cont.)Header172.15.1.1NodeNetwork Logical AddressNetwork Layer End
18、 Station Packet 1999,Cisco Systems,IICND2-26Network Layer Functions(cont.)11111111 11111111 00000000 00000000 10101100 00010000 01111010 11001100BinaryMaskBinaryAddress172.16.122.204 255.255.0.017216122204255AddressMask25500NetworkHost 1999,Cisco Systems,IICND2-27Routing TableNETINT Metric124S0S0E01
19、001.04.01.3E04.3S02.2E02.1S04.14.21.11.2Routing TableNETINTMetric124E0S0S0001 Logical addressing allows for hierarchical network Configuration required Uses configured information to identify paths to networksNetwork Layer Functions(cont.)1999,Cisco Systems,IICND2-28Routers:Operate at the Network La
20、yer Broadcast control Multicast control Optimal path determination Traffic management Logical addressing Connects to WAN services 1999,Cisco Systems,IICND2-29Using Routers to Provide Remote AccessInternetTelecommuterBranch OfficeModem or ISDN TAMobile UserMain Office 1999,Cisco Systems,IICND2-30Tran
21、sport Layer Functions Distinguishes between upper layer applications Establishes end-to-end connectivity between applications Defines flow control Provides reliable or unreliable services for data transferNetworkIPXIPTransportSPXTCPUDP 1999,Cisco Systems,IICND2-31Reliable Transport Layer FunctionsSy
22、nchronizeAcknowledge,SynchronizeAcknowledgeData Transfer(Send Segments)SenderReceiver 1999,Cisco Systems,IICND2-32Network Device DomainsHubBridgeSwitchRouterCollision Domains:1 4 4 4 Broadcast Domains:1 1 1 4 1999,Cisco Systems,IICND2-33Choosing a Cisco Product Distribution LayerCore LayerAccessLaye
23、r 1999,Cisco Systems,IICND2-34Product Selection Considerations Provides functionality and features you need today Capacity and performance Easy installation and centralized management Provides network resiliency Investment protection in existing infrastructure Migration path for change and growth Se
24、amless access for mobile users and branch offices 1999,Cisco Systems,IICND2-35 First select WAN technology solutions based on the following:Availability of serviceBandwidth requirementCost Second,choose products that support selected WAN solutionsProduct Selection Considerations(cont.)Cost per Month
25、UsageLeased Line,T1Modem/ISDNFrame Relay0 1999,Cisco Systems,IICND2-36Product Selection Considerations(cont.)1544128645619.29.64.8Determine applications that you want to runTelnetWeb BrowsingVoiceVideo,MultimediaE-Mail,File Transferkbps 1999,Cisco Systems,IICND2-37Selection Issues:Need for 10 Mbps o
26、r 100 Mbps on media Port density Need for management console Easy OperationsCisco 1500Micro HubCiscoFastHub300Cisco 1528Micro Hub 10/100CiscoFastHub400CiscoFastHub200CiscoFastHub100Cisco Hub Products 1999,Cisco Systems,IICND2-38Selection Issues:Need for 10 Mbps,100 Mbps,or 1000 Mbps on media Need fo
27、r trunking and inter-switch links Workgroup segmentation(VLANs)Port density needs Different user interfaces Desktop/Workgroup SolutionsWiring Closet/Backbone SolutionsCisco 1548 Micro Switch 10/100Catalyst 3000 seriesCatalyst 2900series XLCatalyst 1900/2820 seriesCatalyst 2900 seriesCatalyst 5000 se
28、riesCatalyst 8500 seriesCatalyst Switch Products 1999,Cisco Systems,IICND2-39Selection Issues:Scale of the routing features needed Port density/variety requirements Capacity and performance Common user interfaceCisco700/800SeriesCisco1600/1700 SeriesCisco2500 SeriesCisco3600 SeriesAS 5000 SeriesSmal
29、l Office SolutionsBranch Office SolutionsCentral Site SolutionsCisco12000 GSR SeriesCisco4000 SeriesCisco7000SeriesHome Office SolutionsCisco2600 SeriesCisco Router Products 1999,Cisco Systems,IICND2-40SummaryAfter completing this chapter,you should be able to perform the following tasks:Describe how data moves through a network Identify the roles and functions of routers,switches and hubs,and specify where each device best fits in the network Select the appropriate Cisco equipment for a network that combines switching,routing and remote access requirements
