What is the difference between DWDM and OTN?

Let us begin by understanding what DWDM is.


DWDM represents Dense Wavelength Division Multiplexing. It is a technology in which several optical signals (laser light) of multiple wavelengths or colors are combined into one signal and are sent over the connecting channel to a lengthy area.

When the optical signal transmission distance changes into thousands of kilometers, it results in loss of few signals. It can satisfy this signal loss, optical fibre amplifiers are used in the DWDM transmission system.

The DWDM technology requires this gain bandwidth to send multiple optical signals together effectively. DWDM can address up to 80 channels (80 optical signals) with 100 GHz (0.8 nm) spacing.

Dense Wavelength Division Multiplexing (DWDM) is an optical multiplexing technology that can enhance bandwidth over current fibre networks. DWDM task operates by joining and transmitting several signals concurrently at multiple wavelengths on the same fibre. The technology generates several virtual fibres, therefore magnifying the capacity of the physical channel.

DWDM is treated as one of the best technologies to increase bandwidth over a current fibre plant. It allows one to generate several “virtual fibres” over one physical fibre. It does this by transmitting several wavelengths (or colors) of light down a bit of fibre.

DWDM was originally adopted by high distance carriers because the spending in amplification, dispersion compensation, and regeneration collected most of the network supplied cost in regional and national SONET networks. DWDM became increasingly famous in metro networks when the local exchange carriers produced their networks.


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 increased, thereby 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 large 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.