Metro Networks in the 5G Era
Overall network schematic showing access, metro and core regions.
New 5G networks will not only provide greater bandwidth but also solve problems with existing connectivity, which provides additional functionality for a range of new vertical industries. We spoke to Professor Andrew Lord and Dr Daniel King about the work of the METRO-HAUL project in designing and building scalable infrastructure that services the needs of these potential new applications. The introduction of 5G telecommunications networks will provide not only greater bandwidth to consumers and businesses, but also bring additional connectivity and functionality to new vertical industries. While the provision of increased bandwidth to radio devices is an essential driver behind the ongoing development of 5G, these new, highly-specialised, vertical industries may have other priorities. “They might need very low latency, low jitter, or the ability to perform compute and storage functions, which they might want to set up very quickly,” outlines Professor Andrew Lord. As the Principal Investigator of the METRO-HAUL project, Professor Lord is working to design and build a smart optical metro infrastructure to support different applications. “In METROHAUL, we’re looking at how you architect and build a cost-effective and energy-efficient metro network that can meet the challenging requirements for the upcoming vertical industries in the new 5G era,” he explains. A metro network is just one part of the broader telecommunications infrastructure, that can be compared to the structure of a tree. The core network can be thought
50
of as the trunk, and the metro network as the branches that spread out from it, while the access network is the leaves of the tree which interconnect with customers. “The core network is the big pipes that bring traffic to data centres and internet exchange points around the country. The metro network takes traffic from the access network into central locations such as regional data centres or moves it on to the core network,” explains Professor Lord. The nature of the traffic emanating from the access networks is expected to change significantly with the introduction of 5G, a topic central to the METRO-HAUL project. During the project, attention focused on architecting nodes to interconnect the metro network with the core and access networks. “The access metro edge node (AMEN) is the interface between the access and the metro networks, while the metro core edge node (MCEN) is the interface between the metro and the core networks,” continues Professor Lord. “Those AMENs and MCENs potentially have the IT resources necessary to host both the content and the function necessary to deliver 5G applications.”
METRO-HAUL project The project’s overall agenda also encompasses several other strands of research around the central topic of a metro network, with Professor Lord and his colleagues working to develop a variety of technologies, including optical transmission technologies and overall service orchestration software. Providing services such as augmented reality and holographic communications alongside residential and business internet on a single infrastructure is very difficult: another major topic of interest in the project. “From a networking perspective, companies would previously have simply built different networks to provide these different types of services. This model is not sustainable anymore, especially with exponential growth of bandwidth demand,” says Dr Daniel King, a researcher also working on the project. “One of the goals of METRO-HAUL is to develop a shared optical infrastructure, which is highly malleable, supporting varying traffic characteristics for vertical services.” The project’s work developing a Control, Orchestration and Management (COM)
EU Research
system has been central to this objective. In a 5G network, services and applications run on top of the optical layer infrastructure, which is an essential consideration in terms of partitioning - known as network slicing - infrastructure resources. “Network orchestration and IT control need to come together in order to assign and slice the resources to deliver services,” explains Dr King. This idea of network slicing has attracted much attention as a means of meeting the requirements of particular services. “You essentially partition the physical resource, the network, into multiple virtual slices and instantiate IT resources where required, to meet not just the needs of 5G specific services, but this could service other types of fixed network services as well,” says Dr King. “This infrastructure flexibility is an enabler for achieving some of the 5G KPIs, as well as to meet the techno-economic requirements of future networks.” A flexible network capable of controlling resources when required, including IT, and transport resources, leads to significant savings in infrastructure and operating costs as it can be reconfigured for different purposes and to address varying traffic demands. The sliced aspect addresses the requirements of different use cases and applications; it also provides partitioning and isolation of customer and service traffic. Various options are available in terms of the hardware design of a metro transport network, a
Management of 5G network slicing as part of end-to-end network orchestration.
The recent developments in photonic switching, now with the capability to implement switching using photonic integrated circuits and so reduce costs and power consumption, provides a further example of the opportunities of disaggregation. While photonic switching is well suited to a core network, it is overly expensive and, Professor Lord says, vendors don’t have many different offerings for each customer. Somewhere between the two extremes of everything being supplied by a single vendor, and the networks being built entirely independently, there is a happy medium on the right amount of white box disaggregation. “In this case, we can be more agile, and we can use these innovative new technologies that are emerging,” outlines Professor Lord.
Intelligent systems have been deployed in the network that constantly monitors the network performance against different requirements for each unique type of service. topic Professor Lord and his colleagues have explored in the project. “One option might be to go and buy big complex boxes from a specific manufacturer, but this often locks the network to one type of equipment. We wanted to embrace function separation and break the network into smaller components using commercial off the shelf components, generic servers and white box switches, and glue them together ourselves – so-called disaggregation,” he says. Equipment today is increasingly intelligent, which opens up further possibilities. “We’ve been trying to find ways to enable operators to include new, exciting technology, and not necessarily just from the incumbent vendor,” continues Professor Lord. “You do that by making sure that all of these little bits are intelligent in the ways that they communicate.”
www.euresearcher.com
It is about delivering one of the cornerstones of software defined networking (SDN), namely the separation of control and forwarding planes, and enabling a multivendor capability. Another very important part of the project centred around network monitoring, an area which Professor Lord says has developed dramatically over the last 20 years or so. “In the past, we just didn’t have the capability to monitor the entire network performance in any great detail, but now it seems you can measure just about everything,” he says. While this enhanced capability has much promise, the data gathered is vast and must be dealt with appropriately to make informed decisions automatically. “Part of the project was about building an architecture able to take all this data and handle it in the right way
using distributed machine intelligence,” says Professor Lord. “You don’t necessarily want all that performance data going to a central point and overwhelming human operators.” The architecture has been designed to gather information and process it at the most appropriate point in the network, and then make decisions about network operation. Data can be gathered from different components, and knowledge of which component originated the data may be relevant for decisions on what actions to take. “It’s an event-driven architecture, in contrast to the traditional network infrastructure, which is much more reactive,” explains Dr King. It is not just about collecting vast amounts of information at different layers and points in time, but also analysing it and then making the right decisions based on conditions. “We’ve got the capability to collect the data, store and analyze it. We use machine learning techniques to improve network control – sometimes you need an algorithm that’s good at spotting behaviour that may lead to failure, but at other times you may want to instantiate a network function in a new part of the network to improve traffic efficiency,” continues Dr King. This type of intelligent monitoring allows the metro network to autonomously react to performance degradations, to act before faults occur proactively, and to automatically reconfigure the network to accommodate new services with special requirements as demand changes. This may depend on the types of services for which a network is being used. Remote surgery, where a 5G network is used to enable doctors to perform operations remotely with robots, is one service that has generated a lot of interest. “With remote surgery, we can have a primary and a back-up path and IT nodes that host medical applications. One problem, however, is minimising the delay variation between them. A system has
51