The European Rail Traffic Management System (ERTMS) is becoming a worldwide de facto standard for high-speed railway signaling. A major shortcoming of this system is that it is attached to a single radio-bearer technology, the Global System for Mobile Communications-Railway (GSM-R). The migration of ERTMS toward Internet Protocol (IP) provides the opportunity to make ERTMS unaware of the underlying communication technology by establishing train-to-ground connectivity via multiple bearers. In this article, we evaluate Multipath Transmission Control Protocol (MPTCP) integration in the ERTMS protocol stack in a test bed as a way to use heterogeneous radio bearers seamlessly and simultaneously. We validate this strategy by comparing our obtained results to the European Integrated Radio Enhanced Network (EIRENE) requirements and demonstrate its functionality as a seamless fail recovery strategy.

The deployment of wireless networks in critical industrial environments must ensure the availability of monitoring and control applications, for which it is essential to exploit redundancy techniques. In order to reduce to zero the failover time, in this paper, the Parallel Redundancy Protocol (PRP) is used in Wireless Local Area Networks (WLAN) which are implemented under the Software-Defined Networking (SDN) paradigm. It is discussed how the OpenFlow protocol allows an external controller to configure redundant paths between dual-homed devices. As a result, critical services can be protected in interference and mobility situations. The improvement in availability has been obtained by using both emulation and simulation.

The evolution of the railway sector depends, to a great extent, on the deployment of advanced railway signalling systems. These signalling systems are based on communication architectures that must cope with complex electromagnetical environments. This paper is outlined in the context of developing the necessary tools to allow the quick deployment of these signalling systems by contributing to an easier analysis of their behaviour under the effect of electromagnetical interferences. Specifically, this paper presents the modelling of the Eurobalise-train communication flow in a general purpose simulation tool. It is critical to guarantee this communication link since any lack of communication may lead to a stop of the train and availability problems. In order to model precisely this communication link we used real measurements done in a laboratory equipped with elements defined in the suitable subsets. Through the simulation study carried out, we obtained performance indicators of the physical layer such as the received power, SNR and BER. The modelling presented in this paper is a required step to be able to provide quality of service indicators related to perturbed scenarios.

The telecommunications landscape has been undergoing a major shift in recent years. Initially Software Defined Networking (SDN), and then Network Function Virtualization (NFV) have opened up new ways of looking at the increasingly demanding service provider scenario. The description of the service to be provided will be a key point determining the success in the integration and interoperability of the different proposals. However, the refined understanding of the future scenario and its requirements has recently introduced unique challenges in the path to fully achieve the benefits of the NFV vision. In this paper we review the proposals of service description in the main initiatives related to the NFV arena. Then we elaborate on key novel challenges and evaluate how the different proposals solve them. Finally, we propose a straw man model of service and resource description addressing these challenges and defining the features that would serve as design directions for future initiatives and updates in this topic.

The cyber-security of several industrial plants has been compromised for last years by some worms and viruses, such as Stuxnet, which was able to take control of the Supervisory Control And Data Acquisition (SCADA) system of a nuclear plant in Iran. The research community and the international standardization committees raised their awareness about protecting information in Substation Automation Systems (SAS). IEC 61850-5 and IEC 62351-6 standards respectively describe communication models and the security mechanisms to be deployed in current substations, but they present some inconsistencies. On the one hand, this standard mandates that RSA cryptosystem must be used to provide source authenticity of GOOSE and SV messages. However, despite expensive processors with crypto accelerators were utilized, execution times would exceed the maximum transfer times stated in the standard for most time critical applications. On the other hand, the recommended synchronization solution is the Precision Time Protocol (PTP), as defined in IEEE 1588-2008, which introduced an optional security extension based on old keyed hash algorithms that has also been demonstrated to be suboptimal due to latency times and required resources. The aim of this paper is to explore current available security solutions and study their applicability to the substation environment. Furthermore, as part of the future security framework, a MACsec-based security approach that allows different communication services with diverse performance and security requirements to live together within the substation network is proposed.

The High-availability Seamless Redundancy (HSR) protocol guarantees zero recovery time in case of failure in ethernet networks. However, the management of HSR networks is static and inflexible. This, added to the bandwidth reduction due to data duplication, makes it difficult to efficiently control the network resources. An integration of HSR and OpenFlow technologies is proposed to provide redundancy control and traffic prioritization. As a result, a node can distinguish between critical and noncritical flows, protecting them according to their needs. The effectiveness of the priority-aware network is assessed in terms of throughput efficiency.

Over the last few years, Software-Defined Networking (SDN) has emerged as one of the most disruptive and profitable novelties in networking. SDN was originally conceived to improve performance and reduce costs in Ethernet-based networks and it has been widely adopted in data center and campus networks. Similarly, thanks to the introduction of SDN concepts, access networks will benefit from the higher control, the lower maintenance costs and the better remote access to devices of SDN. However, its application to access networks is not straightforward and imposes great challenges to vendors and network operators, since current SDN technologies are not prepared to handle the provisioning of user equipment, specific port management or QoS requirements of common access networks. Most recent trends dealing with the SDN-ization of access networks advocate for the use of simple devices at the customer premises and the virtualization of the networking functionalities, requiring the provisioning of Layer 2 services in many cases. In such a scenario, this paper presents an architecture that brings SDN to common access networks using legacy equipment. In a nutshell, the architecture is based on the abstraction of the access network as a wide area OpenFlow switch where QoS-enabled pipes are dynamically created leveraging the high granularity of the OpenFlow protocol for packet classification. Furthermore, the OpenFlow protocol itself has been extended in order to support the advanced QoS requirements that are common to most access networks. The architecture has been implemented for DOCSIS access networks and it has been validated and evaluated using a real testbed deployed at our laboratory. The obtained results show that the architecture remains compliant with the ITU-T QoS recommendations and that the cost of introducing the elements required by the architecture in terms of service performance is negligible.

One of the key research issues in further strengthening the role of railways in the transportation system is to achieve the highest possible level of cyber security against significant threats to the signaling and telecom systems. The European Rail Traffic Management System (ERTMS) was designed in the 1990s with the security measures and strategies available at the time. However, ERTMS' underlying communication technology, GSM-R, needs replacing, and replacement strategies are already underway. Due to their direct effects on safety, ERTMS security mechanisms also need updating to face current security threats. This article provides a security analysis of ERTMS' safety layer, Euroradio, in terms of current security threats. After identifying its vulnerabilities, we present four main recommendations: a more robust cryptographic mechanism, a new key distribution scheme, a new key storage and system integrity module, and a set of countermeasures for avoiding radio jamming attacks.

Reliability is a key research issue to promote the role of rail in the transportation system. An important set of critical and vital railway services, such as Traction Power Supply and Supervision Systems, relay currently on modern Supervisory Control and Data Acquisition (SCADA) systems. At the same time, these large scale and networked SCADA systems are deployed over heterogeneous wide area networks. Current strategies to warrant reliability on these systems focus on costly equipment redundancy or retransmission techniques with associated delay penalization. In this paper, we propose a MultiPath strategy with redundant policy to increase reliability in railway SCADA over TCP/IP systems. We built a hybrid simulation tool with real Modbus over TCP/IP equipment and validate our approach comparing the obtained results with three alternative strategies (default TCP/IP, backup and default delivery policy).

IP-enabled sensors can be globally addressable by any Internet-connected entity, and therefore, their protection presents different challenges than that of traditional sensors, as they are subject to any potential attacker in the Internet. For this reason, specific security protocols must be developed to address the security requirements of IP-enabled sensors. An interesting approach to achieve this aim is the Ladon security protocol, which allows resource-deprived devices to efficiently implement end-to-end authentication, authorisation and key establishment mechanisms. However, in so limited environments such as sensor networks, not only efficient protocols must be defined, but they must also be optimally parameterised. This paper constitutes a step forward in this direction. First, a state transition model of the Ladon protocol is presented to analytically describe its behaviour. Then, this model is used to select the most effective parameterisation of the protocol in terms of message retransmissions and execution of cryptographic operations. The obtained results show that the selected parameterisation allows maximising the probability of a successful secure session establishment, while keeping the overhead introduced by the protocol low. Additionally, the performance comparison carried out shows that Ladon outperforms alternative approaches to achieve the same objective in terms of message transmission and reception operations.

The possibility to deploy telecommunication services based on the availability of a fully flow-aware network is an appealing possibility. Concepts like Network Service Chaining and Network Function Virtualization expect the information to be manageable at the flow level. But, for this concept to be available for the development of user-centric applications, the access network should also be made flow-aware. In this paper we present the integration of a legacy DOCSIS based access network under an OpenFlow Control Framework by using the Hardware Abstraction Layer designed in the FP7 ALIEN project. The result is a dynamic wide area OpenFlow switch that spawns from the aggregation switch to the home equipment and hides all the complexity (including the provisioning) of the access technology to an unmodified and standard OpenFlow controller. As a result, the access network can react not only to any kind of user traffic but also to the connection of CPE to the network. The approach used is technology independent, and the results have been successfully demonstrated over a Cisco based DOCSIS access network.

This paper presents FlowNAC, a Flow-based Network Access Control solution that allows to grant users the rights to access the network depending on the target service requested. Each service, defined univocally as a set of flows, can be independently requested and multiple services can be authorized simultaneously. Building this proposal over SDN principles has several benefits: SDN adds the appropriate granularity (fine- or coarse-grained) depending on the target scenario and flexibility to dynamically identify the services at data plane as a set of flows to enforce the adequate policy. FlowNAC uses a modified version of IEEE 802.1X (novel EAPoL-in-EAPoL encapsulation) to authenticate the users (without the need of a captive portal) and service level access control based on proactive deployment of flows (instead of reactive). Explicit service request avoids misidentifying the target service, as it could happen by analyzing the traffic (e.g. private services). The proposal is evaluated in a challenging scenario (concurrent authentication and authorization processes) with promising results.

This paper describes an experimentally-tested approach towards programmability for legacy network elements in the software-defined networking architecture. As OpenFlow is a leading control-plane protocol enabling SDN in modern networks, yet not all equipment is compatible with this framework. This problem is addressed in ALIEN, the FP7 research project, where Hardware Abstraction Layer (HAL) for non-OpenFlow capable devices is introduced. This paper describes outcomes of the project, and specifically, gives a set of examples of the successful implementation of OpenFlow through the HAL on ‘alien’ devices.

Nowadays, several devices supporting OpenFlow versions beyond 1.0 are available on the market. However, existent OpenFlow testbeds like OFELIA do not provide support for such devices, therefore it is hard for the research community to explore and test the newest functionalities of the protocol in realistic environments. This paper gives a short overview of two different architectures investigated within the FP7 ALIEN project that both aim to overcome this limitation within the OFELIA experimental facility.

The rise of cloud services poses considerable challenges on the control of both cloud and carrier network infrastructures. While traditional telecom network services rely on rather static processes (often involving manual steps), the wide adoption of mobile devices including tablets, smartphones and wearables introduce previously unseen dynamics in the creation, scaling and withdrawal of new services. These phenomena require optimal flexibility in the characterization of services, as well as on the control and orchestration of both carrier and cloud infrastructure. This paper proposes a unified programmability framework addressing: the unification of network and cloud resources, the integrated control and management of cloud and network, the description for programming networked/cloud services, and the provisioning processes of these services. In addition proofs-of-concept are provided based on existing opensource control software components.