Synchronizing Digital Networks

It appears that stable synchronization of large digital transmission networks should be easy, granted accurate clocks, buffers which accept pulses at the incoming rate and deliver them at the local clock rate, and adequate delay for making frames coincide. An electric network analog of a simple linear system in ivhich the clock frequency depends on the fullness of buffers and the departure of frequency setting from midsetting makes it obvious that the system is stable. System frequency should be made to depend strongly on accurate or master clocks; criteria are given for choosing parameters to achieve this. Strategies are given for periodic infrequent adjustments to compensate for changes in transmission time, and for adding new clocks to the network. The practical realization of a synchronized network calls for more information concerning variations of transmission time and for adequate components, particularly, buffers and adjustable delay devices. The synchronization of digital networks has been studied theoretically and experimentally. 1-0 This paper does not purport to review excellent previous work, some of which has been highly theoretically oriented, through some results of earlier work are referred to. Rather, it discusses some problems of synchronization and illustrates them by means of a simple analysis of a simple example. We reach the following conclusions: that with good clocks, buffers and adequate delay both to compensate for changes in transmission time and to make frames coincide, there should be no trouble in stably synchronizing a nationwide network.