What is the difference between SONET and OTN?

Let us begin by understanding what Synchronous Optical Networking (SONET) is.


SONET stands for Synchronous Optical Networking. It is a standardized digital connection protocol that can share a high volume of data over relatively long areas using a fibre optic medium. With SONET, there are various digital data streams are shared at the same time over optical fibre using LEDs and laser beams.

SONET provides several streams concurrently and supports efficient services in telecommunication systems. It uses standardized line rates, therefore several types of organizations can be interconnected using SONET.

The network architecture of a SONET depends on transmitting data even if a section of the network has declined. SONET uses a bidirectional line-switched ring which could be either 2-fibre or 5-fibre variants, unidirectional path-switched ring, or linear automatic protection switching.

The SONET approach was generated to restore the plesiochronous digital hierarchy (PDH) system which moved telephone calls or data in huge amounts over the equivalent fibre. SONET allows for simultaneous transport of some multiple circuits of origin within an individual framing system.

Four multiple layers are defined with SONET. These layers are path, line, section, and photonic. Each layer is responsible for specific jobs or applications. The path layer is answerable for the advancement of the signal from the optical source until it reaches its destination. The line layer is where the signal transforms across the cable. The section layer is answerable for the development of signals across a physical section. Finally, the photonic layer correlates to the physical layer of the OSI model and contains requirements for the fibre channel.


OTN represents the Optical Transport Network. It is a transmission network that constructs networks in the optical layer based on wavelength division multiplexing technology and is the next generation backbone transmission network.

The OTN switching structure is combined in the technology, therefore that the system can flexibly dispatch connection services so that the client data can be expanded, promoted, increased, and the network connection service capability is expanded, through solving the traditional WDM network without wavelength/sub-wavelength.

The OTN network has enhanced the perfect solution for the large-bandwidth granular service. The OTN network is set up in the inter-provincial backbone network, the provincial backbone network, and the metro element layer of the telecom functions, and the scheduling of function particles above Gb/s is supported. The provincial backbone network carries long-distance services including PSTN/2G/3G/4G/internet.

The OTN network can execute several forms of protection and has powerful protection capabilities. The backbone network in the province carries services such as the NGW/3G/4G/IPTV high user line between the backbone routers. The metro element network carries the huge granular service among the local network core router and the aggregation router and constructs the provincial backbone network OTN and the metropolitan area network core layer OTN network.

Updated on: 18-Nov-2021


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