The constant growth of the number of Internet of Things devices drives a huge increase in data that needs to be analyzed, at times in real time. Multiple platforms are available for delivering such data to analytics engines that can perform various operations on the data with low processing latency. These platforms can find their home in cloud native environments where high availability and scaling to the actual workload can be easily achieved. While the deployment environment is elastic, clusters still need to be adequately dimensioned to accommodate the components of the platforms even under high load.In this paper, we provide an analysis in this regard: we discuss key performance indicators of the popular Kafka message bus and the related Kafka Streams processing engine. Namely, we analyze latency, throughput, CPU and memory resource footprint aspects of these services under varying load and processing tasks that appear in Internet of Things applications. We find subsecond processing latency and linear but heavily task-dependent scaling behavior in the other performance indicators’ case.

Abstract The massive increase in the Internet of Things (IoT) has brought a diverse long-range, low-power, and low bit-rate wireless network technologies. The LoRa a low-power wide area network (LPWAN) gained popularity as radio technology for the realization of many IoT applications. LoRa is typically employed together with LoRaWAN MAC protocol and operates in the license-free ISM bands. LoRa networks have an issue with scalability when the number of end nodes connected to one network is larger than the shared number of channels, that causes a collision and packets loss through receiving a wide range of different message sizes from various application. In this paper, we describe an accurate and efficient way confirmed by simulation to calculate the probability of collision rate and packet loss in LPWANs under various circumstances. Moreover, based on the LoRaWAN specification, we consider a dense network deployment of IoT devices. In the event of collisions, our proposed algorithms is classified to two approaches. Firstly a time scheduling algorithm is proposed for LoRaWAN networks that consist of devices supporting LoRaWAN class C mode for synchronization in the beginning between the gateway and the end nodes. Afterwards these devices switch to class A to significantly decrease the collision and to enhance scalability by assigning a Guard Time to each end node. Gateway acknowledgment (ACK) messages to the end nodes are used through class C. Secondly, we also propose a distance spreading factor algorithm according to the distance of the end nodes from the gateway to reduce the probability of collision. Furthermore, many of these devices are battery powered, therefore low power consumption is required.

The massive deployment of Internet of Things (IoT) is allowing Smart City projects and initiatives all over the world. The IoT is a modular approach to merge various sensors with all the ICT solutions. With over 50 billion objects will be connected and deployed in smart cities in 2020. The heart of smart cities operations is the IoT communications. IoT is designed to support Smart City concept, which aims at utilizing the most advanced communication technologies to promote services for the administration of the city and the citizens. This paper is presenting a comprehensive review of the concepts of IoT and smart cities and their motivations and applications. Moreover, this paper describes the main challenges and weaknesses of applying the IoT technologies based on smart city paradigms.

The surge of mobile data traffic places strain on 3G/4G cellular networks. At high traffic density areas offloading to Wi-Fi costs less than the expansion of the marco network. However the addition of another (moreover non-3GPP) access technology raises interworking issues. One of them is the selection mechanism of the most suitable access technology and access network by the UE. This demo investigates the feasibility of a system where a network entity activates/deactivates cells and selects the point of access for each UE. The objective is to save power by turning off dispensable network elements while also considering QoS requirements.

Fixed-mobile convergence initially focused on optimizing fixed and mobile telephone infrastructure for voice services. The appearance of VoIP and smartphones, the growing popularity of social networks and video hosting services, the emerging of 5G, Internet of Things, machine-to-machine communication and ever newer over-the-top services motivated manufacturers, network operators and service providers to refocus and data delivery. The tutorial highlights the structural and functional aspects for efficiently instrumenting this convergence process, including infrastructure considerations, network function virtualization, software defined networking, unified functionality. The presentations are embedded into an overview of the past efforts, a summary of the state of the art, and a look-ahead for future communications networks. The authors are members of the Combo European consortium working on fixed-mobile convergence.

Analytical models for all-optical phase-sensitive BPSK and QPSK regeneration are presented, metrics for phase and intensity regeneration efficiency are derived. The models are based on the general principle of operation and do not depend on the regenerator's physical structure. They offer the possibility of simple network planning and comparison of regenerators with fundamentally different physical structures. The models are applied to a simple transmission line with ten equally spaced phase-sensitive regenerators. Nonlinear intensity-to-phase noise transform is observed and signal degradation is described as function of intensity and phase regeneration efficiency.

Several optical access network technologies are available for network operators providing broadband services (FTTx: Fiber-to-the-X solutions). These technologies are now in deployment phase, therefore network and topology design issues play an increasingly important role. In this paper we address br

In both metropolitan optical networks (MON) and long haul optical networks (LHON) the signal quality is often influenced by the physical impairments, therefore a proper impairment based routing decision is needed. In this paper we propose new routing and wavelength assignment (RWA) methods where the control plane has influence on the signal power of the Wavelength Division Multiplexed (WDM) channels. Nowadays in nearly all kinds of reconfigurable optical add-drop multiplexers (ROADM) the signal power can be tuned via variable optical attenuators (VOA) from the control plane. We give the exact integer linear programming (ILP) formulation of the method for both single and multilayer networks. In the first case we assume that no signal regeneration is allowed along the path, while in the more complex multilayer case 3R signal regeneration, grooming and wavelength conversion can all be done in the electronic layer. The proposed algorithm can be used in existing WDM optical networks where the nodes support signal power tuning. The algorithm finds the global optimum, if it exists, for a certain network topology, physical constraints and demand set.

Multi-path routing routes the upcoming demand over multiple paths. This is feasible in networks where the demand can be split into multiple parallel flows, i.e., the network is capable to perform inverse multiplexing (e.g., ngSDH and OTN via VCat) and where the connectivity of the topology also allows it. In this paper we propose the MPP (Multi-Path Protection) scheme, where the demand is not only routed, but also protected using multiple parallel paths. We give a Linear Programming (LP) formulation of the problem that finds the globally optimal solution. The main features of our approach are twofold. First, it always finds a trade-off between the number of parallel paths to be used and the total length of these paths while it balances the traffic optimally between them. Second, we use LP with real variables that is solvable in polynomial time instead of Integer LP (ILP) and still we are able to avoid branching of the flows in nodes different than the source and the target of the considered demand.

In this paper we propose a new traffic engineering scheme to be used jointly with protection in multi-layer, grooming-capable, optical-beared networks. To make the working and protection paths of demands better adapt to changing traffic and network conditions we propose the adaptive multi-layer traffic engineering (AMLTE) scheme that "tailors" i.e., fragments and de-fragments wavelength paths in a fully automatic distributed way.

Shared segment protection (SSP), compared with shared path protection (SPP), and shared link protection (SLP), provides an optimal protection configuration due to the ability of maximizing spare capacity sharing, and reducing the restoration time in cases of a single link failure. This paper provides a thorough study on SSP under the GMPLS-based recovery framework, where an effective survivable routing algorithm for SSP is proposed. The tradeoff between the price (i.e., cost representing the amount of resources, and the blocking probability), and the restoration time is extensively studied by simulations on three networks with highly dynamic traffic. We demonstrate that the proposed survivable routing algorithm can be a powerful solution for meeting stringent delay upper bounds for achieving high restorability of transport services. This can significantly improve the network reliability, and enable more advanced, mission critical services in the networks. The comparison among the three protection types further verifies that the proposed scheme can yield significant advantages over shared path protection, and shared link protection.

The problem of fair and feasible allocation of user throughputs in capacitated networks is investigated. The main contribution of the paper is an extension of network fairness, and in particular, max-min fairness from the traditional "fixed- path" model to a more versatile, routing-independent model. We show that the set of throughput configurations realizable in a capacitated network makes up a polyhedron, which gives rise to a max-min fair allocation completely analogous to the conventional case.

The problem of fair and feasible allocation of user throughputs in capacitated networks is investigated. The main contribution of the paper is a novel geometric approach, which facilitates to generalize several throughput allocation strategies, most importantly max-min fairness, from the traditional "fixed-path" model to a more versatile, routing-independent model. We show that the set of throughput configurations realizable in a capacitated network makes up a polyhedron, which gives rise to a max-min fair allocation completely analogous to the conventional one. An algorithm to compute this polyhedron is also presented, whose viability is demonstrated by comprehensive evaluation studies.

A new concept Quality of Resilience (QoR) presented in this paper is based on the distinction in the reliability-related Quality of Service (QoS) parameters of the short-term quality factors and the long-term quality factors. The former parameters are called availability parameters and the latter are called QoR parameters. In one hand by dividing the service duration time into intervals, the service is considered available during a time interval, if the Service Level Agreement (SLA) between the user and the network operator is satisfied. In the other hand the long-term characteristics of the service are derived from the service downtime distribution. With the downtime histograms the asymptotic characteristics of the service can be represented both at the transport and service layers. Since the resilience mechanism implemented into the network match the transport layer downtime histograms, this new characterization of the QoS helps to measure the impacts of a given recovery scheme on the next generation services.

The low cost and the wide availability make Ethernet the dominant networking technique of access networks. Standardization further extends the capabilities of Ethernet by adding traffic separation and prioritization (802.1Q) and by allowing use of multiple spanning trees (802.1s). In this paper we present an Ethernet based QoS architecture for broadband services with triple play support. We propose an optimization framework with Traffic Engineering where the MSTP trees are spanned taking both the traffic conditions and the QoS requirements into account. The optimization is based on our previously presented formal model. Here we propose a novel decomposition based tree constructing heuristic with high scalability. We conduct simulations to evaluate the performance of the heuristic method that provides nearly optimal solutions within acceptable time constraints.

Shared segment protection (SSP), compared to shared path protection (SPP) or shared link protection (SLP), provides an optimal protection configuration, since SSP can increase the number of connections sharing the same protection segments and can reduce the restoration time in case of single link failure. This paper provides a thorough study on SSP under the GMPLS-based recovery framework, where an effective survivable routing algorithm for SSP is proposed, called shared segment protection (SSP) algorithm. The main advantage of the SSP algorithm is to reduce the high computation complexity in solving the ILP formulation first introduced in P-H. Ho et al., (2004). With an efficient iterative approach the design space is significantly reduced by excluding all the links that result intolerably long routes. The tradeoff between the price (i.e., cost representing the amount of resources, and the blocking probability) and the restoration time is extensively studied by simulations on three networks with highly dynamic traffic. It is demonstrated that the SSP algorithm can be a powerful solution in the GMPLS-based recovery with a stringent delay upper bound for achieving high availability and restorability of the transport services. The comparison among the three protection types further verifies that SSP can yield significant advantages over SPP and SLP.

This paper focuses on the selection of bandwidth-guaranteed channels for communication sessions that require it. The basic idea comes from minimum interference routing: select a feasible path that puts the least possible restriction on the available transmission capacity of other communicating parties. This is achieved by circumventing some critical bottleneck links. The main contribution of the paper is a novel characterization of link criticality, the criticality threshold, which can be readily precompiled for routing dozens of subsequent calls. Based on this finding we define a generic precomputation framework for minimum interference routing, the least-critical-path-first routing algorithm. We show by means of extensive simulations that efficient route precomputation is possible even in the case, when accurate resource availability information is not immediately available.

The minimum cost multicommodity flow problem plays a central role in today's operations research theory with applications ranging from transportation and logistics to telecommunications network routing. In this paper, we introduce a novel Lagrangian-relaxation technique, which, given an initial feasible solution, can solve the minimum cost multicommodity flow problem as a sequence of single-commodity flow problems. Our methodology is best suited for OSPF traffic engineering, because it can rapidly improve a given path set towards approximate optimality while simultaneously provides the link weights, which implement the paths as shortest paths.

This paper focuses on the problem of dynamic survivable routing for segment shared protection (SSP) in mesh communication networks provisioning bandwidth guaranteed tunnels. With SSP, a connection is settled by concatenating a series of protection domains, each of which contains a working and protection segment pair behaving as a self-healing unit for performing local restoration whenever the working segment is subject to any unexpected interruption. We first discuss the advantages of using SSP-the ability to shorten the restoration time as well as achieve a higher throughput by saving spare capacity required for 100% restorability; then the survivable routing problem is formulated into an Integer Linear Programming (ILP), where the switching/merging node pair of each protection domain along with the corresponding least-cost working and protection segment pair can be jointly determined for a dynamically arrived connection request. A novel approach of arc-reversal transformation is devised to deal with the situation that the working segments of two neighbor protection domains may overlap with each other by more than a single node. Due to a very high computation complexity induced in solving the ILP, a novel heuristic algorithm is proposed, named Cascaded Diverse Routing (CDR), to allocate protection domains for a connection request by performing diverse routing across a set of predefined candidate switching/merging node pairs. Experiments are conducted on five two-connected network topologies to verify the ILP and the CDR algorithm. We first determine the best diameter of protection domains for the CDR scheme in each network topology. Using the results of best diameters, CDR is compared with two reported schemes, namely PROMISE and OPDA. We demonstrate in the simulation results that the path-shared protection schemes are outperformed by the SSP schemes in terms of blocking probability under all possible arrangements in the experiment and that CDR yields better performance than PROMISE and OPDA due to the extra efforts in manipulating the location of working segments at the expense of longer computation time.

An efficient and general graph-theoretic model (the wavelength-graph (WG)) has been proposed which enables solution of the static routing and wavelength assignment (RWA) problems in multihop wavelength routing (WR) wavelength division multiplexing (WDM) networks simultaneously, and-as a unique feature-it optimises the optical layer jointly with the electrical one. Based on the proposed WG model the problem has been formulated as an integer linear program (ILP), solved by stochastic algorithms improved by simple heuristics. The topology of the physical layer, the type of each node (e.g., OADM, OXC or EXC), the number of available wavelengths per link and the capacity of each wavelength-channel are assumed given with the aggregated traffic demand of each node-pair. The output of the optimisation is the system of wavelength paths, light paths and semi-light paths. The objective of the optimisation is to reduce resource usage at upper (electrical) layers, subject to the constrained amount of capacity of each wavelength and a limited number of wavelengths. Although the problem to be solved is NP-hard, all methods proposed give a result in a very short time.

A general model and algorithms are presented for the optimal configuration of the ATM layer on top of mostly optical networks. The topology of the physical layer is assumed given with the predefined paths for each node-pair. The output is the size of required ATM switches, and the configuration of both, ATM and optical switches. The obtained result is optimal in the sense of reduced resource usage on ATM level, i.e., reduced electrical processing, subject to capacity and connectivity constraints. The results are derived for WDM networks and generalized for networks with optical cables where multiple fibers per cable are used (space division multiplexing). The idea of layered design is also introduced. Since the problem is discrete by nature with multiple local optima and constraints, non-deterministic constrained discrete global optimization algorithms are used. The running time and the probability of finding global optimum are compared for these algorithms.