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第三章 Copyright ?1998, Cisco Systems, Inc. 物理層和數(shù)據(jù)鏈路層 2 Copyright ?1998, Cisco Systems, Inc. 物理層和數(shù)據(jù)鏈路層標(biāo)準(zhǔn) Physical (bits, signals, clocking) LAN WAN Data Link (frames) E t h e r n e t 8 0 2 . 3 8 0 2 . 5 F D D I LLC Link Frame Relay ISDN PPP EIA530 Dial on Demand SDLC HDLC HSSI EIA/TIA232 EIA/TIA449 3 Copyright ?1998, Cisco Systems, Inc. 局域網(wǎng)數(shù)據(jù)鏈路子層 ? LLC完成上半層的軟件功能 ? MAC完成下半層的硬件功能 Media Access Control(介質(zhì)訪問控制) Logical Link Control (邏輯鏈路控制) Network Data Link Physical LLC MAC MAC Frame LLC Packet or Datagram 4 Copyright ?1998, Cisco Systems, Inc. 物理層和邏輯地址 5 Copyright ?1998, Cisco Systems, Inc. MAC地址 ? MAC地址被燒進(jìn)網(wǎng)絡(luò)接口卡的 ROM芯片中 24 bits 24 bits . 3456 制造商