Many services running on modern digital telecommunications networks require accurate synchronization for correct operation. For example, if switches do not operate with the same clock rates, then slips will occur and degrade performance. Telecommunication networks rely on the use of highly accurate primary reference clocks which are distributed network wide using synchronization links and synchronization supply units.
As service demand grows in metro networks, service providers need to be cost-conscious as they expand or evolve networks to meet new demands. They need to extend the value of installed systems, run more services on existing networks, and retain customers by offering on-demand access to a variety of services. And they want to reduce the cost of providing those services.
SONET and SDH have been widely deployed by telephone companies and common carriers for more than a decade.
ADC’s ThinMux™ product family helps carriers build today's access networks that can easily
adapt to meet tomorrow's needs. Only the ThinMux products provide a single platform to
encompass many universal standards (SONET/SDH, DS3, T1/E1). As bandwidth requirements
increase and network technologies change, ThinMux is quickly and easily upgraded by
replacing the multiplexer card within the chassis. Complete flexibility in delivering unique
T1/E1 (or mixed) services without additional provisioning, servicing, inventory or training is
possible through the one time ADC ThinMux investment....
Synchronous Digital Hierarchy (SDH) and Synchronous Optical Network (SONET)
The synchronous hierarchy digital (SDH) is emergingthe as universal technology for transmission telecommunications in networks. the publication Since first of international standards by ITU-T in 1989, SDH equipment has been rapidly developedand deployed across the world,andisrapidlytakingoverfromitspredecessor,thePlesiochronousDigitalHierarchy (PDH).ThischapterdescribesSDHandtheNorthAmericanequivalentofSDH,SONET (SynchronousOpticalNetwork),fromwhichitgrew...
Unprecedented growth in the telecommunications industry has driven wide-spread deployment of optical
fiber over the past few years. As a result, many service providers are finding that their existing fiber frames
and troughs are overflowing with large masses of optical fiber patch cords. In addition, the rapid
deployment of SONET/SDH, fiber in the loop and video initiatives has created the demand for increased
termination density at the fiber distributing frame.
MDF là điểm trung tâm kết thúc mọi đường dây thuê bao tại tổng đài nội hạt. Các tổng đài nội hạt được kết nối với nhau qua mạng liên đài (inter-CO network). Mạng liên đài bao gồm hệ thống kết nối – truy xuất số (DACS: Digital Access and Cross-connect Systems) và các thiết bị truyền dẫn PDH. Gần đây mạng liên đài sử dụng các công nghệ truyền dẫn tiên tiến SONET hay SDH. Các công ty khai thác điện thoại không đủ khả năng xử lý lưu lượng các cuộc gọi dữ liệu....