What is SONET

Nowadays carrier synchronous digital hierarchy  (SDH) is an international standard for high-speed telecommunication networks. It is a synchronous system which provides simple network infrastructure and it is a more flexible network. SONET is very similar to SDH. SONET is the standard used in the US where SDH is the standard used outside the US also. Before we started the details about SONET/ SDH first we will discuss why using SONET/ SDH and also a full form of SONET.

• In SONET yield thinner cable than copper
• The lower bit error rate
• Higher bandwidth per fiber
• Higher transmission reliability 

SONET network is a transmission interface originally proposed by the broadband ISDN network. Now in this article, we talk about some important characteristics, similarities, major difference between SONET and SDH, SONET network topology. first, now let us check it out some important point SONET as well as SDH.

• SONET is a synchronous network while SDH is also synchronous network with an optical interface.
• SONET interface defines all layers, from the physical to the application layers, while SDH is a set of standard interfaces in a network of elements that conform to these interfaces.

SONET has commonly transmitted data at speed between 155 megabits per second and 2.5 gigabits per second. To the build these high bandwidth data streams, SONET  is multiplexer together channels having the bandwidth as low as around 64-kilobits per second into data frames sent at fixed intervals.

This article gives information about both SONET and SDH  are based on a structure that has a basic frame format and speed. All the base signaling level called STS-1, SONET support 51.84 Mbps and this STS-1 frame can be carried in an OC-1 signal. The SDH level and frame format used by the synchronous transport module(STM).

SONET versus SDH :

• Bitrate and frame format organization
• Frame synchronization schemes
• Error control
• Multiplexing and demultiplexing rules

SONET and SDH rates :

SONET Signal - STS-1, Optical carrier - OC-1

Data rate - 51.84 Mbps

Payload rate - 50.112 Mbps

SONET signal - STS-3,Optical carrier - OC-3,

SDH ITU-T - STM-1

Data rate - 155.52 Mbps

Payload rate - 150.336 Mbps

SONET Signal - STS-9, Optical carrier - OC-9,

SDH ITU-T - STM-3

Data rate - 466.56 Mbps

Payload rate - 451.008 Mbps

SONET signal - STS-12, optical carrier- OC-12
SDH ITU-T - STM-4
Data rate - 622.08 Mbps
Payload rate - 601.344 Mbps

STS-1 - Synchronous transport signal -1 

OC - Optical carrier

STM - Synchronous transport module

ITU-T - International telecommunication union telecommunication standardization sector.

Application of SONET :

• Used for the public telephone network.
• SONET acts as a carrier of multiple higher-level application protocol.
• SONET provides a layer 1 or interfaces layer technology also termed physical layer in the OSI model.
• Used to Multipoint configurations, enhanced performance, monitoring, and enhanced and integrated OAM.

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Advantages and disadvantages of SONET