On the feasibility of collaborative green data center ecosystems

The increasing awareness of the impact of the IT sector on the environment, together with economic factors, have fueled many research efforts to reduce the energy expenditure of data centers. Recent work proposes to achieve additional energy savings by exploiting, in concert with customers, service workloads and to reduce data centers’ carbon footprints by adopting demand-response mechanisms between data centers and their energy providers. In this paper, we debate about the incentives that customers and data centers can have to adopt such measures and propose a new service type and pricing scheme that is economically attractive and technically realizable. Simulation results based on real measurements confirm that our scheme can achieve additional energy savings while preserving service performance and the interests of data centers and customers.Peer ReviewedPostprint (author's final draft

Load-balanced wavelength assignment strategies for optical burst/packet switching networks

Loss-free schemes are defined to ensure successful packet/burst transmissions in optical packet/burst switching networks. To this end, they rely on a collision-free routing and wavelength assignment (CF-RWA) scheme combined with simple contention resolution mechanisms that guarantee the absence of losses in intermediate links. Here, the CF-RWA problem is studied. In particular, by using graph theory, the problem of finding CF-RWA schemes that minimise the number of wavelengths to serve a given traffic matrix is set. The problem is simplified when it is formulated by using pre-defined sets of non-colliding paths. Within this framework, the problem is shown to be equivalent to finding a given vertex-set colouring of the so-called restriction digraph. Here, two heuristic algorithms are proposed to obtain such vertex-set colourings. One of them provides a suitable CF-RWA without having to solve the minimisation problem. By way of example, the proposed method is applied to the NSFNet and the EON network providing quasi-optimal results.Postprint (published version

Load-balanced wavelength assignment strategies for optical burst/packet switching networks

Loss-free schemes are defined to ensure successful packet/burst transmissions in optical packet/burst switching networks. To this end, they rely on a collision-free routing and wavelength assignment (CF-RWA) scheme combined with simple contention resolution mechanisms that guarantee the absence of losses in intermediate links. Here, the CF-RWA problem is studied. In particular, by using graph theory, the problem of finding CF-RWA schemes that minimise the number of wavelengths to serve a given traffic matrix is set. The problem is simplified when it is formulated by using pre-defined sets of non-colliding paths. Within this framework, the problem is shown to be equivalent to finding a given vertex-set colouring of the so-called restriction digraph. Here, two heuristic algorithms are proposed to obtain such vertex-set colourings. One of them provides a suitable CF-RWA without having to solve the minimisation problem. By way of example, the proposed method is applied to the NSFNet and the EON network providing quasi-optimal results

Performance analysis of the sent-but-sure strategy for optical burst and packet switched networks

This work proposes an analytical model to characterize the performance of a loss-free transmission strategy for Optical Burst and Packet Switched Networks, which ensures that a burst/packet will successfully reach its destination once it has been scheduled in the first link of its path. In this paper this strategy is called Sent-But-Sure (SBS) because it avoids losses in any intermediate node. The SBS strategy combines a routing and wavelength assignment scheme with simple contention resolution mechanisms. As a result, new burst/packet allocation attempts in an intermediate node only contend with bursts/packets in transit coming from a single input link. Moreover, bursts/packets in transit always have priority over bursts/packets whose transmission has not been scheduled yet. These two main features of the SBS strategy allow us to develop an analytical model based on a twopriority M/G/1 queueing model to characterize the network performance

Load-balanced wavelength assignment strategies for optical burst/packet switching networks

Loss-free schemes are defined to ensure successful packet/burst transmissions in optical packet/burst switching networks. To this end, they rely on a collision-free routing and wavelength assignment (CF-RWA) scheme combined with simple contention resolution mechanisms that guarantee the absence of losses in intermediate links. Here, the CF-RWA problem is studied. In particular, by using graph theory, the problem of finding CF-RWA schemes that minimise the number of wavelengths to serve a given traffic matrix is set. The problem is simplified when it is formulated by using pre-defined sets of non-colliding paths. Within this framework, the problem is shown to be equivalent to finding a given vertex-set colouring of the so-called restriction digraph. Here, two heuristic algorithms are proposed to obtain such vertex-set colourings. One of them provides a suitable CF-RWA without having to solve the minimisation problem. By way of example, the proposed method is applied to the NSFNet and the EON network providing quasi-optimal results

Fully Synchronous SDN (FSS): towards synchronization-as-a-service in 5G networks

Many modern telecommunications systems rely on strict timing and synchronization requirements. Synchronous Ethernet (SyncE) and Precision Time Protocol (PTP) are widely used to provide frequency and phase synchronization in current 4G and future 5G backhaul and core networks. This paper describes how the synchronization capabilities provided by these two technologies can be managed as a service following the SDN/NFV paradigm, thus opening the way for a virtualized syncronization control plane in 5G core and access networks.Postprint (author's final draft

SDN-based management of time-sensitive networks in 5G fronthaul

Software Defined Networking is a key element in the 5G architecture, as it allows a more flexible, dynamic network management. Cloud RAN is another enabler of 5G, due to the expected increased based station density in the fronthaul. In Cloud RAN deployments the I/Q signals are transported in the CPRI format over access networks, thus requiring QoS guarantees regarding loss, bandwidth and latency. TimeSensitive Networking (TSN) is a new technology that introduces synchronous capabilities in Ethernet networks, and is one of the most promising technologies for 5G fronthaul and backhaul. Therefore, the SDN-based management of TSN is an important topic, in order to coordinate the fronthaul, backhaul and core 5G networks. The IEEE 802.1Qcc and 802.1CM working groups are currently standardizing the SDN management of TSN and the use of TSN in the fronthaul. This paper describes the architecture and state of the standards, and presents a design and implementation status of a TSN SDN-based controller

Fully Synchronous SDN (FSS): towards synchronization-as-a-service in 5G networks

Many modern telecommunications systems rely on strict timing and synchronization requirements. Synchronous Ethernet (SyncE) and Precision Time Protocol (PTP) are widely used to provide frequency and phase synchronization in current 4G and future 5G backhaul and core networks. This paper describes how the synchronization capabilities provided by these two technologies can be managed as a service following the SDN/NFV paradigm, thus opening the way for a virtualized syncronization control plane in 5G core and access networks

SDN-based management of time-sensitive networks in 5G fronthaul

Software Defined Networking is a key element in the 5G architecture, as it allows a more flexible, dynamic network management. Cloud RAN is another enabler of 5G, due to the expected increased based station density in the fronthaul. In Cloud RAN deployments the I/Q signals are transported in the CPRI format over access networks, thus requiring QoS guarantees regarding loss, bandwidth and latency. TimeSensitive Networking (TSN) is a new technology that introduces synchronous capabilities in Ethernet networks, and is one of the most promising technologies for 5G fronthaul and backhaul. Therefore, the SDN-based management of TSN is an important topic, in order to coordinate the fronthaul, backhaul and core 5G networks. The IEEE 802.1Qcc and 802.1CM working groups are currently standardizing the SDN management of TSN and the use of TSN in the fronthaul. This paper describes the architecture and state of the standards, and presents a design and implementation status of a TSN SDN-based controller.Postprint (author's final draft