QUESTION: Why is it necessary to spend so much time and effort on synchronization in telecom networks when the basic requirement is so simple, especially when computer LANs have never bothered with it?
ANSWER: The requirement for PRS traceability of all signals in a synchronous network at all times is certainly simple, but it is deceptively simple! The details of how to provide traceability in a geographically distributed matrix of different types of equipment at different signal levels, under normal and multiple-failure conditions, in a dynamically evolving network, are the concerns of every sync coordinator. Given the number of permutations and combinations of all these factors, the behavior of timing signals in a "real-world" environment must be described and analyzed statistically. Thus sync distribution network design is based on minimizing the probability of losing traceability while accepting the reality that this probability can never be zero.
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