OTN (Optical Transport Network) and DWDM (Dense Wavelength Division Multiplexing) are both technologies used in optical communication networks, but they serve different purposes and operate at different layers of the network. 

1. OTN (Optical Transport Network):

• Multiplexing: Combines multiple lower-speed signals into a higher-speed optical signal for efficient transport.

• Forward Error Correction (FEC): Adds error correction codes to enhance signal reliability.

• OAM (Operations, Administration, and Maintenance): Includes features for monitoring, managing, and troubleshooting the network.

• Compatibility: OTN can carry various client signals, such as Ethernet, SONET/SDH, and Fibre Channel.

• Purpose: OTN is a set of standards for the transport of diverse services (voice, video, and data) over optical networks. It provides a framework for efficiently transporting and switching different types of traffic at the optical layer.

• Layer: OTN operates at the network layer (Layer 3) of the OSI model.

• Functions:

2. DWDM (Dense Wavelength Division Multiplexing):

• Multiplexing: Combines multiple wavelengths on a single fiber, enabling the parallel transmission of multiple data streams.

• Increased Capacity: DWDM dramatically increases the capacity of a fiber optic network by allowing for the transmission of multiple signals on different wavelengths.

• Long-Distance Transmission: DWDM enables the transmission of signals over long distances without the need for regeneration.

• Transparent Transmission: DWDM is agnostic to the data format and can transport various protocols and services.

• Purpose: DWDM is a technology that allows multiple optical signals to be transmitted simultaneously over a single optical fiber using different wavelengths (colors of light). This significantly increases the capacity of the fiber optic infrastructure.

• Layer: DWDM operates at the physical layer (Layer 1) of the OSI model.

• Functions:

In summary, while OTN is focused on the efficient transport and management of diverse services over optical networks, DWDM is specifically designed to increase the capacity of optical fiber infrastructure by using multiple wavelengths. They can be complementary technologies, with OTN providing a higher-layer network framework and DWDM providing the physical layer capability for high-capacity data transmission.