??: 3.?????Circuit-switched networks ?

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?????? ??
?? 3.?????Circuit-switched networks ?
Packet- switched networks???
4.????????????????????
???????????????????(? ?????)
?????
??935602 ??? 935604 ??? 935625 ???
935627 ??? 935645 ??? 935651 ???
935657 ???
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?????Circuit-switched networks?Packet-switched
networks ???
Packet-switched networks ??? 1. ????????????(Wide
Area Network, WAN)?2. ?????????(LAN)????????????
?????????????????3. ?????????(Intranet)??????(Ex
tranet)?????? 4. ??ITU(?CCITT)??????,???????????
??,???????????,?????5. ???????????????????????
??????,??????????,???????????????????,?????????,??
?????,?????????????,?????????,????????????????????
???
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6. ????????????????????????,??????????,?????????
?????,????????????(Bits Error RateBER)??
,??????????????? ,???????????????????????7.
????????????????????????,?????????(CUG)?????(PVC
)??????(NUI)???????(VPN)???,???????????? 8.
?????????????????????????????????,??????????????
,??????????? 9. ???????????,???????????????????
????????,?????????????,??????????????????,????????
?????????????,???????????????????,???????????????
10. ??????????????????????(Gateway),??????????
?????????,????????????????????
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11. ???????????????????,???????????????????????
?,??????????????,??????????????,??????????(VPN)???
????,????????????????????12. ?????????????????
???????????,???????????????,?????????????,????????
?????????? (1) ?????(Pernament Virtual
CircuitPVC)?????????????(Logical
Channel)???(??)?,?????????????????????? (2)
?????(Switched Virtual CircuitSVC)?????????????(
Logical Channel)????(???),?????????,??????????????
,????????????,???????,???????????
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(3) ????(Closed User Group)??????????????????,???
???????????,??????????,????????????? (4)
????(Hunt Group-Collective Number
Group)???????????????????????????????,???????,???
?????????,????????,???????????????????????? (5)
??????(Virtual Private NetworkVPN)????????,?????
????,?????????????????,????????????,??????????????
???,??????(VPN)???????????????,??????????????????
???? ? ?????? ? ???????? ?
????,???? ? ????,????? ? ???????? ?
???????? ? ??????? ? ????????????
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(6) ??????(VPN)?????? ? ????????????????
? ???????????? ? ?????????????? ?
???????????????????? ? ???????????????????
? ?????????????? ? ???????????
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• Circuit-switched networks ???
• 1.???????(dedicated),????????
• 2.?????????????,??????????????,?64Kbps??????,?????
  ,?????????,??????????,??????????(full duplex)
  ?????,??? connection oriented?
• 3.???????????
• ???? ( FDMFrequency Division Multiplexing )
• ??????????????????????
• ???? ( TDMTime Division Multiplexing )
• ??????????????????????
• ???????????????? ( Guard Time ),???????????????

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???????????????????????????????????????(??????)
?
?????????????????? ??????????????????????????,???
????,??,??,?????,???????,???????
1?????????????????????????,??????????????????????
???????????,?????????????,????????????????,???????
?????,??????????????,??????????,?????????????????
2???????????????????????,??100M??(?????,???????),
??????????,????????100M,???????????????????,?????1
00M????(?568B?568A)?? ?
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3????????????????????????????????,??????????????
4?????????,????????????????????????,????????(???CP
U????,??,??,??)???????????????,????????????
5????????????(???????)?????????????,????????,????
???????????????????
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???????????CAT7?CAT8,CAT7?????600MHz,CAT8??1.2
GHz,CAT8????????????IBM???3P(Third Party
Testing)??????????,??????????Enterprise(??)?Home(?
?) ?Mobility(??) ,???????????????????,???????????(
Entertainment)????????????,????????????????(Video
on Demand)????????,?????????????????????????(100?)
??,????CAT8????SOHO???????????????,???CAT8??????1.
2GHz?50??????(Channel),????????,??????????????(Thi
n Client)????,?????????????????????,??????????????
???????,???????????????????,???????????????????
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???? Cat3 Cat3 Cat5 Cat5 Cat5e Cat5e Cat6 Cat6 Class C Class C Class D Class D Class E Class E Class F Class F
???? PL CH BL PL PL CH PL CH PL CH PL CH PL CH PL CH
??(Attenuation) ??dB 13.0 14.9 21.6 24.0 21.0 24.0 31.1 36.0 12.6 14.9 20.4 24.0 30.7 35.9 46.6 54.6
????(NEXT) ??dB 21.0 19.2 29.3 27.1 32.3 30.1 35.3 33.1 21.1 19.3 32.3 30.1 35.3 33.1 54.7 51.2
??????(PSNEXT) ??dB ? ? ? ? 29.3 27.1 32.7 30.2 ? ? 29.3 27.1 32.7 30.2 51.7 48.2
?????(ACR) ??dB ? ? ? ? ? ? ? ? ? ? 11.9 6.1 4.7 -2.8 8.1 -3.4
???????(PSACR) ??dB ? ? ? ? ? ? ? ? ? ? 8.9 3.1 2.0 -5.8 5.1 -6.4
???????(ELFEXT) ??dB ? ? 17.0 17.0 18.6 17.4 16.2 15.3 ? ? 18.6 17.4 16.2 15.3 32.6 31.3
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????????(PSELFEXT) ??dB ? ? 14.4 14.4 15.6 14.4 13.2 12.3 ? ? 15.6 14.4 13.2 12.3 29.6  
????(Return Loss) ??dB ? ? 10.1 8.0 12.0 10.0 10.0 8.0 15.0 15.0 12.0 10.0 10.0 8.0 10.0  
????(Propagation Delay)??nSec ? ? 518 555 498 555 498 555 498 555 498 555 498 555 498  
????(Delay Skew) ??nSec ? ? 45 50 44 50 44 50 44 50 44 50 44 50 26  
???? 16MHz 16MHz 100MHz 100MHz 100MHz 100MHz 250MHz 250MHz 16MHz 16MHz 100MHz 100MHz 250MHz 250MHz 600MHz 600MHz
?? ????????????
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PL??????? BL??????? CH?????
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