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Difference between SONET and DWDM

Last Updated : 16 Sep, 2022
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1. Synchronous Optical Network (SONET) : 
SONET stands for Synchronous Optical Network. This is a communication protocol, developed by Bellcore which is used to transmit a large amount of data over relatively larger distances by using optical fiber. By this, multiple digital data streams are transferred at the same time over the optical fiber. 

2. Dense wavelength division multiplexers (DWDM) : 
DWDM stands for Dense wavelength division multiplexers. This is modules that put data from different sources together on a fiber optic cable. These modules further increase system bandwidth and capacity by using closely spaced wavelengths to carry multiple signals on the same cable. The channel spacing is reduced to 1.6 nm and less. The cost effective way of increasing capacity without replacing fiber. There is commercial systems available with capacities of 32 channels and upwards. 

Difference between SONET and DWDM :

1. SONET is a optical transmission interface. DWDM is WDM utilizing closely spaced channels.
2. In this, SONET aggregates a number of optical signals into higher bit rate signal for transmission over a single fiber using a single wavelength. In this, DWDM assigns the incoming optical signals to specific frequencies multiplexes them for transport over a single fiber.
3. It uses Time division multiplexing(TDM) or statistical TDM. In this, multiple channels of information carried over the same fiber, each using an individual wavelength.
4. These are technologies that are used as a buffer (interfacing) layer for higher layers. It increases the bandwidth of systems, without using repeaters.
5. The channel spacing can be carried over WDM, but not vice versa. The channel spacing is small 200GHZ.
6. The band used are STS-1 with fixed size frames. The band used are C and L.
7. It is easy to isolate one channel from a multiplexed circuit. There is hundreds of channels is possible.
8. The best application is ethernet cabling or public telephone network. The best application is Long-haul.
9. For the same traffic, the more number of topological structures are required. For the same traffic, the less number of topological structures are required.
10. It is less costly in comparison to DWDM . It is more costly.
11. Requirement of more optical fibers than DWDM. Relatively less optical fibers are required.


  • Decreased cost
  • Extreme effectiveness
  • Permits transmission of all traffic types 
  • Easy demultiplexing
  • It provides network resilience capabilities.
  • Both legacy and future networks can use it.


  • Improvement in scalability
  • Capable of preserving switched bandwidth
  • Greater capacity for fiber
    amplify your resilience
  • Allows multiple logical topologies to be used instead of a single physical MAN
  • Easier network growth
  • Ability to extend span length


  • No interoperable standards exist.
  • Issue of bandwidth effectiveness at higher capacities.
  • With few channels, low cost is efficient.


  • Not economical given the small channel numbers
  • Requirement of large space
  • Requirement of more power
  • Greater startup costs 
  • Advanced technology demands
  • High precision wave filters and lasers

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