Types of Redundancy Checks-Cont

-Lines Europeans use a version of T-lines called E-lines Two are conceptually identical but capacities vary Line     Rate(Mbps)     Voice channels ------------------------------------------------

E-1 E-2 E-3 E-4 Fiber to the Curb (FTTC)

Optical fiber has many advantages: -Noise Resistance -High BW Capacity Very Expensive Telephone & Cable companies have devise FTTC to employ optical fiber while keeping the expense down Optical Fiber is the medium from the Central Office of the telephone company or from main office of a cable company to the Curb The  medium  from  the  Curb  to  the  subscriber's  premises  if  the  less  expensive twisted pair or coaxial cable    FTTC in Telephone Network o    Optical Fiber is used to connect and multiplex different voice channels o    Copper   twisted   pair   coming   from   individual   premises   is   multiplexed   in junction   boxes   and   converted   to   optical   signals.   Optical   signals   are  multiplexed  using  WDM  at  switching  office  to  create  wider  BW  optical