Contents

1 Introduction

On a larger scale, the telecommunications industry uses the SONET or SDH standard for optical transport of TDM data. SONET, used in North America, and SDH, used elsewhere, are two closely related standards that specify interface parameters, rates, framing formats, multiplexing methods, and management for synchronous TDM over fiber.

SONET/SDH takes n bit streams, multiplexes them, and optically modulates the signal, sending it out using a light emitting device over fiber with a bit rate equal to (incoming bit rate) x n. Thus traffic arriving at the SONET multiplexer from four places at 2.5 Gb/s goes out as a single stream at 4 x 2.5 Gb/s, or 10 Gb/s.

2 Description

• High-speed (up to 2.5 Gbps) synchronous network specification developed by Bellcore and designed to run on optical fiber.
• Was approved as an international standard in 1988.
• STS-1 is the basis building block of SONET.
• SONET, used in North America, and SDH, used elsewhere, are two closely related standards that specify interface parameters, rates, framing formats, multiplexing methods, and management for synchronous TDM over fiber.