Building metropolitan networks based on the traditional WDM and SDH

because of its own restriction

has caused many problems

for example

the relatively low width utilization ratio

the complicated level of the network and simple interface form etc

which can’t very satisfy the requirements of modern communication. With the development of technology

there appears the improved technology and products from the traditional bases

such as OADM

MSTP. This text

from two respects mentioned above

emphatically introduced the technology of building the new generation metropolitan networks.