Green networks go deeper than just the energy savings

Dec 16, 2013

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Over the last six years, there has been a constant focus on carbon reduction around IT systems, both inside and outside the data centre. Most of that attention has been on power, cooling, servers and storage. According to Ian Wilkie, supply chain director at Brand-Rex, the next phase is to look at the network and the supply chain:

Supply Chain

Look at any large company and you will find they have publically embraced the need for a “green” policy. One of the ways that many companies can make quick gains around their green credentials is in the supply chain. Not everything, for example, can be green. If you are commissioning data centres you have to use concrete. Every tonne of concrete releases 410kg/m3 of CO2e. Few CIOs want to know what the carbon footprint of each item in the IT infrastructure.  Instead, the enterprise is focused on what it can control; its own carbon footprint. That is changing. Vendors such as Brand-Rex are now talking openly about the carbon footprint of some of their products. Customers can begin to factor into their supply chain, the carbon footprint of the products they purchase. It is a major step forward for any company that wants to understand its ethical and environmental responsibilities and the first time any major IT vendor has done this. Examples of green project investments include a hydro-dam project in Turkey where the power for purifying copper is generated – plus a project to improve transportation energy-efficiencies through the introduction of regenerative braking technology. These projects, along with other carbon reduction measures – such as pulp inserts, reduced manufacturing plant conversion energy and un-bleached boxes – helped Brand-Rex lower its products carbon footprint by over 1000 tonnes in a year. Such investments and savings might not be applicable for every customer. What they do enable customers to know is that that they are buying from a carbon sensitive company.

Inside the data centre and comms room

Savings in the network start with simple things such as virtualisation, better cable management and choice of cabling. Before any choice of cable is made, good management and practice is essential. Key gains such as better aisle containment, making sure blanking plates are fitted, that there are no air leaks around racks and that hot and cold air are not mixing are basic requirements.


A big problem for older data centres and comms rooms – and one that still exists in new builds – is the location and cooling of switches. Historically, located at the back of racks, this is where the majority of the heat exists in today’s higher-powered racks. A good solution is to use ducts to channel cold air from the front of the rack and feed it to the input side of the switch. Another duct vents hot air to the back of the cabinet. This increases switch reliability and prolongs life and helps to ensure that cold and hot aisles are properly separated without air short-circuits.

Ports mean power

Every active port on every switch consumes power. On older switches that's a lot of power; because the ports are always on and always transmitting at a power level high enough to drive a full 100 metre link – even if the link is only 20m. Even more power is consumed day-in and day-out if the port supports Power over Ethernet. A switch technology refresh can often be justified simply by the power savings that can be achieved across the estate. Newer, more advanced switches contain smart power control. Often referred to as EEE (energy efficient Ethernet), these devices switch off the transmitters in the PHY (physical interface) when not needed, detect when far-end devices like PCs are inactive and instigate sleep-mode. They even measure the length of the link when active – turning down their power draw to match. The operating systems of these switches have the facility to completely de-activate the PHYs of individual ports so that they consume no power at all. Even though switch ports individually use only a watt or two, by the time you’ve multiplied that by 10,000 or so around the estate and each burning power 8,860 hours per year you will understand why – as far back as 2005 – it was estimated that the combined pool of switch ports in the USA devoured 5.3Terawatt hours (TWh) of energy a year. Imagine what that figure would be were it not for technology like EEE.

Make space for air

10Gigabit/s cabling is required by the data centre standards and is being installed in an increasing proportion of enterprise projects.  But some standard UTP Category 6A cables are bulky, and seriously impede both in-rack and under-floor airflow. So cooling fans have to work harder and draw a lot more power. Shielded Cat6A cables are smaller in diameter whilst some specifically designed for the data centre like Brand-Rex zone cable is as thin as Cat5e cable freeing up the airflow and allowing fans to slow down and use less power.

Fibre or copper

If 10Gbit/s is the highest speed your network will ever need then copper is probably the answer. You can lay-in Cat6A cables well in advance of need, but fit only EEE Gigabit switches. In fact you can save power by delaying the roll out of more power hungry 10Gb/s switches until they are absolutely needed. If fibre is an option for your application, then consider the power consumption for single-mode versus multi-mode versus copper and factor this into your business case. Bear in mind that one pair of single mode fibres will handle 1Gb/s, through 10 and 40 right up to 100Gb/s with no changes to the cabling. Multi-mode fibre goes from needing two fibres for 10Gb/s to eight for 40Gb/s and 20 for 100Gb/s. Add into your thinking that it is now possible to purchase Zero-Carbon footprint copper cabling – but so far only from Brand-Rex.


The use of virtualisation is well understood for servers inside modern data centres. What is not done well, and this has been due to a technology lag, is network virtualisation. Replace 1GbE copper with 10GbE copper or fibre or even 40GbE – and then virtualise the capacity. This has several benefits. ·        Less space requirement for the cabling. ·        An option to increase network capacity per link should traffic demand it. ·        Easier to create redundant links by running two fibres rather than 20 copper cables. ·        Longevity as single mode fibre supports higher speeds now and will not need to be replaced as switches are replaced. There are some drawbacks as well. ·        Fibre is inherently more difficult to patch or replace onsite although this can be overcome by training. ·        Fibre ports generally draw more power than copper but this can be offset by the ability to virtualise multiple copper cables.


The network is often overlooked as an opportunity to improve power efficiency and reduce carbon footprint. Yet network vendors such as Brand-Rex are able to deliver carbon savings as part of the supply chain and as part of the equipment in the data centre. With environmental concerns rising up the corporate governance chain, it's time to take a hard look at your network and how it can deliver unexpected benefits.

Guest blog post by Ian Wilkie, Supply Chain Director at Data Centre Networking Specialists Brand-Rex