OTN hierarchy enhances delivery in next generation networks

Operators are seeking new technical solutions to the ever-present challenge of containing network costs, while creating enough capacity to accommodate growing traffic levels. Pressure for high quality of service (QoS) and rising bandwidth for services, such as video and mobile broadband, means that simply adding more “best effort” internet protocol (IP) packet capacity is not enough. The bit-rate hierarchy of Optical Transport Networks supports the layered approach needed to enhance each area of network performance.

Faced with the need to switch and multiplex signals of ever larger bandwidth, as transparently as possible, while preserving visibility of their digital contents for monitoring, the ITU-T recommended OTN as a new format to carry packet and non-packet traffic. This was specified to accommodate the dramatic growth in traffic while minimizing power consumption, equipment size, capex and opex, while adding features to improve network performance and management.

OTN defines network architecture requirements, interfaces and a hierarchy of bit rates. Together, these form a key part of the transformation that is being provided by next-generation networks (NGN). NGNs converge a range of services onto a shared network, itself based on a mixture of technologies, in contrast to the formerly frequent and more costly arrangement of a separate network or "silo" or "stovepipe" per service.

Based on electrical processing, OTN takes over where SDH/SONET runs out of capacity. It is much simpler than packet processing and complements the optical processing done in WDM systems.