  The exponential growth in networks' traffic accompanied by the multiplication
of new services like those promised by the 5G led to a huge increase in the
infrastructures' energy consumption. All over the world, many telecom operators
are facing the problem of energy consumption and Green networking since many
years and they all convey today that it turned from sustainable development
initiative to an OPEX issue. Therefore, the challenge to make the ICT sector
more energy-efficient and environment-friendly has become a fundamental
objective not only to green networks but also in the domain of green services
that enable the ICT sectors to help other industrial sector to clean their own
energy consumption. The present paper is a point of view of a European telecom
operator regarding green networking. We address some technological advancements
that would enable to accelerate this ICT green evolution after more than 15
years of field experience and international collaborative research projects.
Basically, the paper is a global survey of the evolution of the ICT industry in
green networks including optical and wireless networks and from hardware
improvement to the software era as well as the green orchestration.
