The metro has been the main surport of the backbone

because the backbone was perfect. There are many technologies such as MSTP

OADM and CWDM for metro network

especially the OADM equipments are the main solution on the core and convergence layer. In this article

first we will give the introduction about the OADM technology and characteristics. Second

we talk about the advantage and application of CWDM equipment for metro access network. And last

we will discuss the development of the OADM or CWDM technoloies and relationship between OADM

CWDM and ASON.