текст 6 задания 19-20

19

ASCII – American standard code for information exchange

SONET, SDH – synchronous digital hierarchy

OAM&P – operations, administration, maintenance and provisioning

ATM – asynchronous transfer mode

ADSL – asymmetric digital subscriber line

20

Broadband access and service

1. Transmission is now done via fiber, information is a string of 1’s and 0’s.

2. There are not enough coding schemes, most popular – SONET, ATM, ADSL

SONET

1. For optical communication. Defines technology for carrying mant signals of different capacities through a synchronous optical hierarchy.

2. Governs interface parameters, formats, multiplexing methods and OAM&P for high speed transmissions. SONET rings – transmission in one direction, if there is a fault in equipment – reverse direction.

ATM

1. High performance switching and multiplexing technology, fixed length packets for different types of traffic.

2. Multiple streams of traffic can be multiplexed on each physical facility and sent to different destinations.

ADSL

1. Modem with sophisticated coding scheme. Over copper 6 Mb/s.

2. Advantage – target applications function with low upstream rate.

Nowadays transmission in telecommunications networks is digital in nature – information is presented in binary form as a string of 1’s and 0’s. Therefore they must be correctly arranged, take optimal routes and be transmitted at optimal speed…