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1、第三章第三章Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3物理层和数据链路层物理层和数据链路层 2Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3物理层和数据链路层标准物理层和数据链路层标准Physical(bits,signals,clocking)LANWANData LinkData Link(frames)(frames)Ethernet802.3802.5FDDI802.2 LLCX.25LinkFrameRelayISDNPPP EIA-530V.35DialonDeman
2、dSDLC HDLCV.24HSSIG.703 EIA/TIA-232EIA/TIA-4493Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3局域网数据链路子层局域网数据链路子层LLC完成上半层的软件功能完成上半层的软件功能MAC完成下半层的硬件功能完成下半层的硬件功能Media Access Control（介质访问控制）（介质访问控制）Logical Link Control （逻辑链路控制）（逻辑链路控制）NetworkNetworkData LinkData LinkPhysicalLLCLLCMACMAC Frame 802.3
3、LLC802.3 LLCPacket or Datagram4Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3物理层和逻辑地址物理层和逻辑地址5Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3MAC地址地址MAC地址被烧进网络接口卡的地址被烧进网络接口卡的ROM芯片中芯片中24 bits24 bits0000.0c12.3456制造商代码制造商代码序列号序列号ROMRAM6Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3MAC地址判定
4、地址判定Host YHost ZQueryResponseExample 1:Destination localRouter AExample 2:Destination not localHost ZBroadcastHost ZMAC?Host ZHost YMACHost ZMACHost YQueryBroadcastHost ZMAC?Host ZResponseHost YMACRouter AMACRouting Table:Net forHost Z7Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3练习练习:MAC地址判定地
5、址判定Host AHost BHost DRouter CRouter CNetwork YNetwork X局域网技术局域网技术 Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.39Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3EthernetToken RingFDDILAN 技术概览技术概览FDDIDual Ring10Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet和和IEEE 802.3Ethernet是一种
6、共享介质的技术，它允许多是一种共享介质的技术，它允许多台设备同时连接、交替使用同一传输介质。台设备同时连接、交替使用同一传输介质。11Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3的物理层的物理层Host10BaseT双绞线双绞线10Base2以太网细缆以太网细缆 10Base5以太网粗缆以太网粗缆PCMacSunHostHubMAC12Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3接口接口Cisco路由器的路由器的Ethern
7、et/802.3的接口名字使用字母的接口名字使用字母E加一个数字加一个数字(例如：例如：E0)a560000.0c12.7c4dE0E10000.0c12.83e213Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3工作原理工作原理A AB BC CD D14Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3工作原理工作原理A AB BC CD D15Copyright?1998,Cisco Systems,Inc.ICRC_revi
8、sion_11.3Ethernet/802.3工作原理工作原理A AB BC CD DDApplicationPresentationSessionTransportNetworkData LinkPhysical16Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3工作原理工作原理A AB BC CD DDB and CApplicationPresentationSessionTransportNetworkData LinkPhysicalApplicationPresentationSessionTrans
9、portNetworkData LinkPhysical17Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3 广播广播DCBAApplicationApplicationPresentationSessionTransportNetworkData LinkPhysicalApplicationApplicationPresentationSessionTransportNetworkData LinkPhysicalApplicationApplicationPresentationSessionTranspo
10、rtNetworkData LinkPhysicalApplicationApplicationPresentationSessionTransportNetworkData LinkPhysical18Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3A AB BC CD DEthernet/802.3 的冲突检测的冲突检测19Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3的冲突检测的冲突检测A AB BC CD D20Copyright?1998,Cisc
11、o Systems,Inc.ICRC_revision_11.3Ethernet/802.3的冲突检测的冲突检测C CD DCollisionA AB B21Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3的冲突检测的冲突检测CollisionA AB BC CD DC CD DA AB B22Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3的冲突检测的冲突检测A AB BC CD DCollisionA AB BC CD DJAM
12、JAMJAMJAMJAMJAMJAMJAMJAMJAMJAMJAM23Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Ethernet/802.3的冲突检测的冲突检测A AB BC CD DCollisionA AB BC CD DJAMJAMJAMJAMJAMJAMJAMJAMJAMJAMJAMJAM广域网技术广域网技术 Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.325Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3WAN 技术
13、概览技术概览SDLCHDLCLAPBPPPX.25Frame RelayISDN26Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3WAN的物理层协议的物理层协议(Modem)Data Terminal Equipment（与数据通信网相连的用户设备）（与数据通信网相连的用户设备）DTEData Circuit-Terminating Equipment（数据通信网末端设备）（数据通信网末端设备）CSU信道服务单元信道服务单元DSU数据服务单元数据服务单元DCEEIA/TIA-232V.35X.21HSSIOthersCSU/DSU27Co
14、pyright?1998,Cisco Systems,Inc.ICRC_revision_11.3WAN接口电缆接口电缆28Copyright?1998,Cisco Systems,Inc.ICRC_revision_11.3Data Link Layer:WAN ProtocolsSDLCSynchronous Data Link ControlHDLCHigh-Level Data Link ControlLAPBLink Access Procedure,BalancedFrame RelaySimplified version of HDLC framing PPPPoint-to-Point ProtocolX.25Packet level protocol(PLP)ISDNIntegrated Services Digital Network(Modem)CSU/DSUCSU/DSU(Modem)