SONET Synchronous Optical Network

SONET Synchronous Optical Network

  • Multiplex electrical signals (Digital) from different sources and creates optical carrier (OC).
  • USA, CANADA and JAPAN developed T1 Standard.
  • ANSI develop  SONET.
  • The rest of the world uses a primary rate of E1.
  • ITU-T develop  SDH.




  • What is SONET?
  • What is Synchronous Digital Hierarchy?
  • What is SDH?
  • What is Synchronous Optical Network?
  • What is ITU standard?
  • What is PCM?
  • What is E1?
  • What is T1?
  • What is PDH?
  • What is STS-1?
  • What is synchronous Optical network?
  • What is SPE?
  • What is Synchronous payload envelope?
  • What is SONET layer architecture?
  • What is SONET network element?
  • What is virtual tributary?
  • What is sonet digital hierarchy?
  • What is sonet data rate?


  • Standard Multiplexing format.
  • Optical standard to utilize maximum bandwidth of optical network.
  • Easy administration and OAM (VC or VT level monitoring is possible)
  • To reduce the complexity of PDH.
  • To accommodate existing signal structure.
  • To create space for future demands.

SONET Layers architecture

Path Layer.

It is responsible for the movement of signal from optical source (STS multiplexer) to optical destination (STS demultiplexer. Path overheads are added here and make SPE.

  • Data identification inside the SPE (ATM,IP or etc).
  • Path status checking.
  • Multi frame indication if data is not fit in one frame.
  • Path end to end verification.
  • Some bytes reserved for future use.
Line Layer.

Line layer is responsible for the movement of signal between MUX, DeMUX and ADM. Line overhead s are added here.

  • Error checking over a line
  • Operation, Administration and maintenance signalling over a Line
  • Order wire communication over line level
  • Automatic protection switching
  • Some bytes reserved for future use

Section Layer.

It is responsible for the movement between every section / device. Section overheads are added here.

  • Alignment, framing and synchronization
  • Error checking over a section
  • Frame identification
  • Operation, Administration and maintenance signalling over a section
  • order wire communication over section level
Photonic Layer.

It is identical to the physical layer of OSI model.


Share This Post

One Response to "SONET Synchronous Optical Network"

Post Comment