We hear a lot about smart cities and few will disagree with the need to make our cities more liveable, sustainable and economically viable. But to realise this vision, smart city initiatives need to be supported and integrated by an intelligent communications infrastructure, a role tailor-made for Software-Defined Networks.

An SDN approach means better manageability, integration, and accessibility. These are key requirements if smart city initiatives are to scale beyond today’s laboratory and small-scale pilot projects, and so deliver tangible benefits to the city as a whole.

Put simply, the idea behind a smart city is to foster greater interaction between people, places and things. To make that happen will require investment in a wide range of technologies, including ubiquitous fixed and wireless broadband access networks, M2M communications, IoT technologies, and big data tools.  Equally, with current 6GB Internet devices set to become 25GB by 2020 there will also be a very real demand for ways to transfer data more efficiently and, most importantly, cost effectively.

A good example of what smart city technologies can offer is taking shape in Bristol. The project, dubbed Bristol is Open collects information about many aspects of city life, such as energy, air quality and traffic flows, from a large number of sensors, including lamp post-mounted sensors and the smartphones of Bristol residents who have agreed to participate in the project.

The data generated is anonymised and can be freely accessed through Bristol’s open data portal. The portal already contains a wide variety of datasets presented in human-friendly form, such as maps showing real-time pollution or journey times, or charts showing the city’s installed capacity of photovoltaic panels.

Of course, there are many challenges in building this type of city-wide intelligent infrastructure. Firstly, the network has to offer the scalability to cope with the huge projected growth in data traffic. According to Cisco, metro traffic is already growing more than twice as fast as data traffic on long-haul networks and will account for 66 percent of total IP traffic by 2019. Those growth projections don’t include the additional bandwidth required to handle M2M traffic and other types of smart city application.

Bristol, fortunately, had the prescient decision to buy an old cable TV network 20 years ago. This has has been upgraded with fibre optic cable to create a 30GB backbone infrastructure, which is supplemented by Wi-Fi networks and an RF mesh network for the lamp post sensors.

But the challenges posed by smart city applications cannot be addressed by simply building bigger data pipes. A smart city consists of a wide variety of smart and dynamic applications that require access to geographically distributed sources of information. In addition, each service will have its own specific needs in terms of bandwidth, availability, latency and other QoS parameters.

Using conventional network planning and management tools would be a nightmare scenario for any network administrator which is why the Bristol is Open initiative is instead using a software defined network (SDN) to manage the M2M communications.

Using SDN offers much greater flexibility and agility than a hard-wired network infrastructure. It means, for example, that the behaviour of the myriad devices attached to the network can be programmed “on the fly” by network managers using automated SDN programs as new requirements and services emerge.

The network management framework used by Bristol is Open is based on OpenDaylight, the same open source framework that Aria Networks uses for its carrier-class Virtual Network Optimisation Architecture.

This allows carriers to understand how their networks will be impacted by changes in traffic and growth, or helps them decide on the best way to route services or reconfigure the network.

The SDN approach has been proven in the field by Aria’s carrier customers, who today face the same types of network management challenge that smart city networks will face in the near future.

Thanks to SDN, the world’s cities have the technology to turn the vision of smart cities into a working reality.