Initially deployed for voice service, Sonet/SDH has played a major role in today's service
provider networks. In the past 10 years, the next generation SDH has become a robust
platform solution to transport voice, video, and data. However, with the fundamental
technology yet based on TDM, existing equipment architectures can not scale sufficiently to
meet the tremendous data demands in future. Furthermore, as the number of network nodes
increases, provisioning and managing these network nodes is becoming increasingly
The evolution of optical transport networks poses challenges to service providers on how to
support existing TDM services, while addressing the rapid growth of data services, such as
triple play and Ethernet virtual private networks (VPNs), etc. To remain competence, carriers
are looking for ways to cut Capex and Opex while delivering new revenue generating and
profitable services.At the same time, this evolution is a challenge to equipment suppliers as
well. Transport tend to integrate TDM and packet services seamlessly, which enables network
element to deliver carrier-class, standardized and packet optimized services.
In this paper, three technical solutions for transport node will be introduced, and their cost,
functions, advantages and disadvantages will be compared as well.