Chapter 7 / 7.11 / 7.11.7

7.11.7 What Are SONET And SDH, And Why Were They Developed?

Understand why the limitations of plesiochronous digital hierarchies led to synchronous optical transport systems. Learn how SONET and SDH simplified multiplexing, enabled very high data rates, and became the backbone of global telecommunications networks.

1. What Are SONET and SDH?
2. Why Were New Standards Needed?
3. What Problems Did PDH Create?
4. What Does "Synchronous" Mean?
5. How Does Synchronization Improve Multiplexing?
6. What Is the Basic SONET Hierarchy?
7. What Is the SDH Hierarchy?
8. Are SONET and SDH Compatible?
9. What Is a SONET or SDH Frame?
10. Why Is the Overhead Important?
11. What Are Add-Drop Multiplexers?
12. Why Was This Such an Improvement?
13. Why Are SONET and SDH Well Suited to Optical Fiber?
14. Were SONET and SDH Used Only for Telephone Calls?
15. Are SONET and SDH Still Used Today?
16. Did SONET and SDH Influence Modern Networks?
17. Why Are SONET and SDH Important?

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