The market of metro optical networking has increased rapidly over the last few years. Traditional telecommunication infrastructure has an emphasis on long-haul optical transmission with ultra broadband capacity, relying mostly on large pure Dense Wavelength Division Multiplexing (DWDM) systems. Today, however, metro core optical networks take the major role in provisioning local access services and interconnecting service points of presences (POPs) with long-haul transmission. This represents a pivotal point in business operations of data communication services for service providers and large enterprises. In addition, the upper layer data services completely leans upon the substrate wavelength communication, and hence the survivability and reliability issues in the optical domain are now becoming crucial topics. This paper provides a detailed discussion around the development process of protection technologies in metro core optical transport infrastructure.