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The Segment Routing (SR) architecture is based on loose source routing. A list of instructions, called segments can be added to the packet headers, to influence the forwarding and the processing of the packets in an SR enabled network. In SRv6 (Segment Routing over IPv6 data plane) the segments are represented with IPv6 addresses, which are 16 bytes long. There are some SRv6 service scenarios that may require to carry a large number of segments in the IPv6 packet headers. This can be inefficient due to the overheads of the segment list, or can even cause processing issues in the crossed nodes due to the very large header to be processed. In this paper we present the Micro SID solution for the efficient representation of segment identifiers. With this solution, the length of the segment list can be drastically reduced., Comment: Extended version (v1) of submitted paper - October 2020

We consider the IPv6 Segment Routing (SRv6) technology for Service Function Chaining of Virtual Network Functions (VNFs). Most of the VNFs are legacy VNFs (not aware of the SRv6 technology) and expect to process traditional IP packets. An SR proxy is needed to support them. We have extended the implementation of SRv6 in the Linux kernel, realizing an SR-proxy, referred to as SRNK (SR-Proxy Native Kernel). The performance of the proposed solution (SRNKv1) has been evaluated, identifying a poor scalability with respect to the number of VNFs to be supported in a node. Therefore we provided a second design (SRNKv2), enhancing the Linux Policy Routing framework. The performance of SRNKv2 is independent from the number of supported VNFs in a node. We compared the performance of SRNKv2 with a reference scenario not performing the encapsulation and decapsulation operation and demonstrated that the overhead of SRNKv2 is very small, on the order of 3.5%., Paper accepted to 5th IEEE International Conference on Network Softwarization (NetSoft 2019)

The exploitation of Internet services leveraging multiple and different access links simultaneously is becoming a compelling use-case in current networks and upcoming 5G scenarios. In fact, recent network architectures and technologies enable multi-link access with the aim to improve both performance and service resilience/reliability. Performance improvement mainly concerns the increase of physical bandwidth through the “bonding” of multiple links, whereas reliability comes from the opportunity to implement handover and failover procedures over multiple links. At the transport layer, MP-TCP protocol was introduced as response to these needs to efficiently work on multiple links. Nonetheless, when one of the links in use is satellite (being very different in characteristics with regard to terrestrial links), it is possible to reach sub-optimal performance. The scope of the paper is to show in depth the working principles of MP-TCP before addressing, in such challenging environment, the impact of different network configurations by using a real Linux-based testbed. The results obtained can be considered as useful recommendations to future Internet Service Providers for their network configuration.

This paper presents the investigation and calculation of the maximum sloshing height of water inside the spent fuel pool (SFP), the spent fuel racks (SFR) are kept in partially filled SFP. Under the seismic condition, the sloshing of the free water surface in the pool can cause overflow. For the safety assessment, it is necessary to know the maximum sloshing height of the water. It is difficult to predict the nonlinear sloshing phenomenon of the water, when it’s occur. In this investigation and calculation, The Computational Fluid Dynamic (CFD) is used for simulation under seismic excitation; the Volume of fluid (VOF) model were applied to get an accurate outcome of water free surface displacement in the SFP, three different excitation frequency (three cases) were applied. A model of the SFP and SFR are designed for validation. The comparison of the maximum water free surface displacement result of the SFP showed the difference between CFD and experiment for case one (natural frequency) with SFR for left and right walls are 0.641, 1.666mm respectively, for the natural frequency without SFR the results showed that the sloshing load is stronger, higher amplitude and over flow is observed, for the case two (3.577Hz) the maximum difference for left and right wall with SFR is 0.52,0.362mm respectively, and without SFR 1.666, 0.646mm respectively, for the case three (10.731Hz) the maximum difference for left and right wall without SFR is 1.148, 0.828mm respectively, at the begging of excitation of non- resonant frequency between the first and second mode(10.731Hz), the water sloshing start rising and gradually declined. From above comparison the CFD simulation results is accepted to predict the maximum sloshing is the SFP. SFR can suppress the sloshing effectively and sufficiently reduce the water sloshing as well.

Video streaming is nowadays the dominant Internet application contributing to most of the generated IP traffic. In the 5G era, network slicing and dynamic management can lead to link changes due to handover for offloading and/or optimization purposes, making bottleneck bandwidth and experienced latency varying over time. In this framework, satellite can play a role for an efficient backhauling in several challenging scenarios. Therefore, Adaptive Bit-Rate (ABR) capability in the streaming applications is of paramount importance not only to face up network load variations (usual design requirement), but also to take into account physical changes. This paper aims to investigate performance of two MPEG-DASH ABR algorithms, which mainly cover the main adaptation approaches (throughput-based and buffer-based), on simulated scenarios stressing the link change events and introducing at least a satellite link. The overall performance analysis leverages on the Network Simulator NS-3.

Telecommunication networks are complex systems in term of design, development, management and maintenance. The degree of complexity greatly increases when the network is composed of several segments adopting different technologies and standards, as well as the sharing of common resources. Development of suitable models of networking and their implementation using simulation and emulation tools are of paramount importance to address such a complexity in a laboratory-controlled environment. To tackle different aspects of satellite and terrestrial integrated networks, which cover different protocol layers and technology standards, different simulative or emulative approaches are possible. A presentation and selection of simulation and emulation tools is presented in this paper, followed by the description of results obtainable with the selected tools in some explicative study-cases.

In this paper we consider the use of IPv6 Segment Routing (SRv6) for Service Function Chaining (SFC) in an NFV infrastructure. We first analyze the issues of deploying Virtual Network Functions (VNFs) based on SR-unaware applications, which require the introduction of SR proxies in the NFV infrastructure, leading to high complexity in the configuration and in the packet processing. Then we consider the advantages of SR-aware applications, focusing on a firewall application. We present the design and implementation of the SERA (SEgment Routing Aware) firewall, which extends the Linux iptables firewall. In its basic mode the SERA firewall works like the legacy iptables firewall (it can reuse an identical set of rules), but with the great advantage that it can operate on the SR encapsulated packets with no need of an SR proxy. Moreover we define an advanced mode, in which the SERA firewall can inspect all the fields of an SR encapsulated packet and can perform SR-specific actions. In the advanced mode the SERA firewall can fully exploit the features of the IPv6 Segment Routing network programming model. A performance evaluation of the SERA firewall is discussed, based on its result a further optimized prototype has been implemented and evaluated.

Contention Resolution Diversity Slotted ALOHA (CRDSA) random access scheme, introduced in the DVB-RCS2/NG standard, is specifically designed to support the transfer of a variety of traffic profiles that Machine to Machine (M2M) and Internet of Things (IoT) applications may generate. Protocols for M2M and IoT has recently receiver substantial upgrades, but still mainly designed with an underlying terrestrial network in mind. If clusters of sensor nodes exchange data via satellite terminals toward a sink via short-lived TCP/IP connections, many shortcomings may incur. This work aims at investigating in details the behavior for such data transfer in presence of a shared random access channel, and the advantages when using a new TCP version specifically designed for satellite links, namely TCP Wave. In particular, through a detailed simulation campaign based on the NS3 simulator, this work assesses the completion time of data delivery for M2M elastic traffic via CRDSA satellite random access, when standard TCP (NewReno) or dedicated satellite TCP (Wave) is adopted.

Service Function Chaining (SFC) allows the delivery of advanced end-to-end services composed of one or more network functions. IPv6 Segment Routing (SRv6) is a network architecture based on source routing, where a list of segments is attached to packets to enforce different path from the shortest one. SRv6 supports SFC by assigning each network function a segment and combining these segments into a segment list. In order to fully leverage the SRv6 network programming capabilities, network functions are required to be SR-aware. In this paper, we present our implementation of SR-Snort, a SR-aware intrusion detection system (IDS) and intrusion prevention system (IPS). We extended the open-source implementation of Snort, so it can apply the configured rules to the inner packet of SR traffic. SR-Snort can handle both inner IPv4 and inner IPv6 traffic. It can work in either IDS or IPS mode.

TCP Wave changes the typical TCP transmission paradigm by replacing the ACK-clocked sliding window with self-scheduled bursts. In response to bursts, unmodified TCP receivers generate ACK trains, which carry useful information about the end-to-end link characteristics. TCP Wave inspects ACK-train flow to measure the following parameters: (i) ACK train spread (namely ACK train dispersion) and (ii) RTT variations. The former is expected to provide the overall “service capacity”, meant as the maximum capacity allowed over the end-to-end path, while the latter is considered as a congestion indicator. The joint use of such measurements allows TCP Wave to fine-tune the transmission rate to accurately match current network resource availability in the bottleneck link. This paper analysis TCP Wave ACK train-based measurements on a broad set of simulated links compliant to characteristics of today's real networks. To this scope, a testbed with TCP Wave implementation on Linux OS is used to perform tests varying both bottleneck capacity and physical latency.

In last few years, the Dual Mechanical Ports (DMPs), based on Permanent Magnet Machines (PMSMs), are intensively researched to be used as an Electric Variable Transmission (EVT) in Hybrid Electric Vehicles (HEVs). However, there is a lack of research work on the area of global control strategy in EVT-based HEVs. In this paper, a novel global power management strategy is developed, which involves three Fuzzy Logic Controllers (FLCs) for strategizing the power flow and torque distribution. The FL controllers are designed based on the state of charge of the battery, vehicle's velocity, traction torque, and the vehicle's requested power. The integration of the studied system is accomplished via the Energetic Macroscopic Representation (EMR) simulation model strategy based on the software Matlab/Simulink. The PM-EVT based HEV system with the proposed power management strategy is validated by comparing to the Toyota Prius HEV. Also, the work involves the analysis of the role of drivetrain, energy management control strategy and the associated impacts of fuel consumption. The simulation results show that global control system is effective to control the engine's operating points within the highest efficiency region, exploiting of EVT machines for capturing maximum braking energy, as well as to sustain the SOC of the battery while satisfy the drive ability.