Network Overview

Abstract

The optical transport network (OTN) was created with the intention of combining the benefits of SONET/SDH technology with the bandwidth expansion capabilities offered by dense wavelength-division multiplexing (DWDM) technology. In addition to further enhancing the support for operations, administration, maintenance and provisioning (OAM&P) functions of SONET/SDH in DWDM networks, the purpose of the ITU G.709 standard (based on ITU G.872) is threefold. First, it defines the optical transport hierarchy of the OTN; second, it defines the functionality of its overhead in support of multiwavelength optical networks; and third, it defines its frame structures, bit rates and formats for mapping client signals. In order to begin describing the OTN as defined by the ITU G.709 standard, we must first enumerate its critical elements, their termination points, and the way they relate to one another in terms of hierarchy and function.