Time transfer characteristics of a WDM-SDH-Based ATM System

摘要

NTT will realize a time synchronization network in a new system that provides ATM (Asynchronous Transfer Mode) services. The system transfers ATM cells via SDH (Synchronous Digital Hierarchy) frames that are transmitted over WDM (Wavelength Division Multiplexing) networks. We have finished the initial measurement of the basic characteristics of the system in an experimental environment, and have started a field test, whose purpose is to collect realistic system reliability data for a couple of months. This paper describes time keeping systems in the new ATM network, some initial measurement results such as the time path switching algorithm and its influence on time accuracy, and the time accuracy and stability of the system in the field.