:
l ;
l PDH (Plesiochronous Digital Hierarchy ( ) ) 1/1, 2/2, 3/3, 4/4, ( 1-T4, 1-E4). ;
l SONET/SDH ( 1984 Synchronous Optical Nets, Synchronous Digital Hierarchy ), ;
l ISDN (Integrated Services Digital Network ), (, , );
l ADSL (Asymmetric Digital Subscriber Line) .
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l (TDM Time Division Multiplexing), () (-). .
l (FDM Frequency Division Multiplexing), , , , , ADSL.
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l ;
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(transmission mode) . ( ):
l (simplex mode),
l (half-duplex mode),
l (full-duplex mode).
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l , ( V.29) ;
l , .. . ( V.21, V.22, V.22bis) ADSL.
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