Accession Number : ADP009103

Title :   Cascaded Clocks Measurement and Simulation Findings,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GREENBELT MD GODDARD SPACE FLIG HT CENTER

Personal Author(s) : Chislow, Don ; Zampetti, George

Report Date : 02 DEC 1993

Pagination or Media Count : 18

Abstract : This paper will examine aspects related to network synchronization distribution and the cascading of timing elements. Methods of timing distribution have become a much debated topic in standards forums and among network service providers (both domestically and internationally). Essentially these concerns focus on the need to migrate their existing network synchronization plans (and capabilities) to those required for the next generation of transport technologies (namely, the Synchronous Digital Hierarchy (SDH), Synchronous Optical Networks (SONET), and Asynchronous Transfer Mode (ATM). The particular choices for synchronization distribution network architectures are now being evaluated and are demonstrating that they can indeed have a profound effect on the overall service performance levels that will be delivered to the customer. The salient aspects of these concerns reduce to: (1) identifying that the devil is in the details of the timing element specifications and the distribution of timing information (i.e., small design choices can have a large performance impact), (2) developing a standardized method of performance verification that will yield unambiguous results, and (3) presentation of those results. Specifically, this will be done for two general cases: an ideal input, and a noisy input to a cascaded chain of slave clocks.

Descriptors :   *TIME STANDARDS, *SYNCHRONISM, CLOCKS, DISTRIBUTION, HIERARCHIES, NETWORKS, SELECTION, SPECIFICATIONS, TRANSPORT, VERIFICATION.

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE