As the penetration and extension of packet switch technologies into the optical layer

Optical Packet Switching（OPS） offers an ideal platform for multiple services including voice and data in the future optical networks and

driven by IP services and promoted by the continuously developing optical switch technologies

is sure to have a broad prospect of applications This article describes the layering structure and the network architecture of OPS-based transport networks

gives the layering reference model of the existing OPS transport networks in near

middle and distant future phases of development

on the basis of which it discusses the migration strategies for optical transport networks to OPS-based transport networks.