FEATURE ENVIRONMENT
2.5Gb/s GPON-based FTTP optical network units (ONU) more energy-hungry than the 80Mb/s modems that BT customers use. However, evidence shows FTTP definitely
helps to reduce overall power consumption, Lord adds. ONU consumption should diminish, because it’s envisioned multi-wavelength passive optical network (PON) systems will have standardised power saving modes. Furthermore, the outside plant for FTTP needs no power. ‘FTTP optical line terminals (OLTs) can support many more customers using PON than other technologies given the same bandwidth,’ Lord said. ‘Te footprint at the local exchange or metro node is reduced, and so is the cost to communications providers who consume backhaul products.’ BT is trialling different ultrafast FTTP GPON
variants with Chinese vendor Huawei. Te 10G down and 2.5G up XG-PON and 10G symmetric XGS-PON protocols consume slightly more energy than basic GPON, but consume less power per bit and have mandatory power-saving modes. However, the current generation of equipment supporting NG-PON2, though operating at the same data rate of 10Gb/s up and down, will have power consumption far greater than XG(S)-PON, Lord explains. Despite this, power-saving modes are again mandatory, and power consumption per bit is expected to be lower than prior PON technology. ‘It is possible to shut down OLT PON transceivers in low traffic conditions by moving all active ONUs in the PON to a single wavelength,’ Lord added. By contrast progress in optical technologies
offers little benefit to data centre energy consumption, Lord points out, as converting data from electronic to optical format itself consumes energy. ‘Within the data centre, transmission distances are short so that data rates need to be very high before optical transmission gives you an end-to-end energy benefit,’ he explained. Telia Carrier consumes the majority of its
Careful consideration of where Telia Carrier locates its points of presence, like this one at the Jaguar Network’s data centre in Marseille, France, is helping control its energy consumption
power in data centres – and Fridström stresses that they are becoming more efficient. ‘Tere is enormous pressure on people that make equipment in the data centres to consume less power, from the content people, the ISPs, and us, the carriers,’ he said. ‘Five years ago, most people said the best performance was always the winner. Now it´s sometimes more focus on how much power the box consumes than how many megabits it can transfer. As long as performance is good enough, then the power consumption is the key factor.’ And Telia Carrier’s transformation to a
lower-emission network has involved a lot of effort in planning ideal locations, to reduce the energy associated with sending data over longer distances. ‘Because energy consumption has become such a big proportion of our total cost, we have to be very much more careful about where we are, where we can afford to be,’ Fridström said. ‘We have started to look at making sure that we’re not just staying in the location where we have one
The Global e-Sustainability Initiative (GeSI) estimates that ICT could help avoid greenhouse gas emissions equivalent to an enormous 12 billion tonnes of carbon dioxide
or two customers because we don’t want to upset those customers. It’s better that we tell them “If you would move your service, we would save money and thereby provide you with more cost-effective services”. Maybe we only need four places in a city, we don’t need to be in six or eight.’ Tis cuts power consumption, but Telia
Carrier is further reducing the emissions it is responsible for by buying power from renewable
As long as performance is good enough then the power consumption is the key factor
sources where possible. Where its points of presence (PoPs) are located is also an important consideration, Fridström explains. ‘We need to carefully review where to store our equipment,’ he said. ‘PoPs where heat and cooling is reused will always be a preferred alternative. Unfortunately, there are not many out there yet. PoPs buying their power from renewable resources will also be preferred.’ Telefónica also intends to adopt renewables,
aiming to convert to them while keeping its energy consumption stable in the face of growing traffic. ‘Tere is a very strong process to reduce our energy costs and consumption as much as possible on the basis of efficiency,’ Paemen explained. ‘We will stabilise them as much as possible and at the same time reduce emissions because we will be increasing, gradually, our use
22 FIBRE SYSTEMS Issue 15 • Spring 2017
@fibresystemsmag |
www.fibre-systems.com
GeSI
Telia Carrier
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