WAN 是覆盖地理范围相对较为广阔的数据通信网络,它一般是利用公共载体(比如电信公司) OSI 的最下 3 层 广域网(Wide Area Network,WAN)的一些术语 (customer premises equipment,CPE):位于用户(subscriber)前端,用户所拥有的 设备 | Chapterl 1 Wide Area Networking Protocols Introduction to Wide Area Networks wan M wiAaffiWAAi tm a majaaa w aaam wmmiwan aaaaa osi w t 3 a A l Wide Area Network WAN A AAA 1. AA roA customer premises equipment CPE ÈANA subscriber A ANAAWAW A- 2. AAA demarcation point MftW service provider SP Al CPE lAAIKA AAAA telecommunication W CSU DSU AA ISDN nAA MWO 3. AM0 local loop AA AaA lJ 1 A central office CO AAAMA 4. CO aANAllJWAffiAAA lAAA AHt CO A point of presence POP 5. toll network Internet service provider ISP MA -AAlAAAA A AlAlA WAN Connection Types WAN a AA AS 3. packet-5 itched l lif synchronous serial dedicated lines WHÜJft leased Ines A AfT asynchronous serial ISDN 2. ci reui t-switched @ 1 AAA AWBA A AAAS .MAASAWfflA A A AA A fflaA AAaw a .HAswwaA asM aAAAAa AWA AAi W O i É æWiS WX fe ttMMWFrame Relay M llJ 45Mbps - Æ HDLC PPP fôM fë 2 mM wœmi ww m o H tfît fiMS .-ftfflfM t5 fiS ftt. Tt Integrated Service Digital Network ISDN .router fà i ié Æ aTOfômwe .w isDN nm a isdn m m 2 W m W tWMtëmœW 3 M tfl M ffl itMMMj WÆ wwM i t w mwtt ra .b fê Æxra a a m W S W W ATM .j g W 56Kpbs lj T3 fô 45Mbps TS WAN Support WAN IL-AWL mCFrame Relay i fômMW XM OSI fô X 2 BPWŒ BXÄXM mmT g fâ- S ttÿgng 8SIS M MHWrami fô WAN Ml WfôWW A 64Kbps W T3 fô fô X ÎBWMfêÆÜ tc ISDN M 1 ÆB fôXiW XWÎB Wfô dial-up Mfô Sa Wm WtëÆ ISDN fôX .ISDN W Mb AwAn Ti miwwmi 3. XW Wï BÎS Link Access Procedure Balanced LAPB X X OSI fô B M 1 ftfflfoMMlB ft - Âfî i xe x m w 4. ÄÄW High-Level Data-Link Control HDLC SXXÉ IBM ftJM ö fê Synchronous Data Link Control SDLC X OSI fô . m LAPB HDLC XÄHDLC M ftI mO 1 X . Xrffi fô HDLC WfeiB XI WfôX X Xrffifô HDLC MX fô Xfô 5. XXXWX. Point-to-Point Protocol PPP 1 X feBindustry-standard WfXHÄ- Xrffi fô HDLC w ppp xxmx rwB oho Network Control Protocol NCP X ŒX fô OSI X fôI WX 6. fë Asynchronous Transfer Mode ATM S X X fe M ITU-T XfôitX cell W féBATM ÆH fô