Harald Øverby

IEEE INFOCOM 2021 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS) Doi: https://doi.org/10.1109/INFOCOMWKSHPS51825.2021.9484513

Systems 9(4) s. 1-23 Doi: https://doi.org/10.3390/systems9040085

The multisided platform (MSP) is an essential business construct in the digital economy. Some of the largest companies in the world—including Google, Amazon, and eBay—exploit the MSP in their business models. Fundamental insights into the MSP are crucial to understand the business operations of the digital economy and how new innovative digital services are adopted in the market. The MSP ecosystem is complex and dynamic, and involves heterogeneous stakeholders with different business motivations. This paper classifies the various types of MSPs, distinguished by the network effect between user groups. Moreover, this paper shows how the original diffusion model of Frank Bass can be extended to analyze the temporal evolution of multisided platforms. Analytical models using coupled sets of ordinary differential equations are developed for several examples of two-sided platforms. For some of these examples, analytical solutions are found.

2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit) s. 377-382 Doi: https://doi.org/10.1109/EuCNC/6GSummit51104.2021.9482469

TeraFlow proposes a new type of secure, cloud-native Software Defined Networking (SDN) controller that will radically advance the state-of-the-art in beyond 5G networks by introducing novel micro-services architecture, and provide revolutionary features for both flow management (service layer) and optical/microwave network equipment integration (infras-tructure layer) by adapting new data models. TeraFlow will also incorporate security using Machine Learning (ML) and forensic evidence for multi-tenancy based on Distributed Ledgers. Finally, this new SDN controller shall be able to integrate with the current Network Function Virtualization (NFV) and Multi-access Edge Computing (MEC) frameworks as well as to other networks. The target pool of TeraFlow stakeholders expands beyond the traditional telecom operators towards edge and hyperscale cloud providers.

2020 IEEE Conference on Cognitive and Computational Aspects of Situation Management (CogSIMA) Doi: https://doi.org/10.1109/CogSIMA49017.2020.9216102

arXiv.org Doi: https://doi.org/10.1364/opex.12.000410

Lecture Notes in Computer Science (LNCS) 11594 LNCS s. 149-163 Doi: https://doi.org/10.1007/978-3-030-22351-9_10

The most costly cybersecurity incidents for organizations result from the failures of their third parties. This means that organizations should not only invest in their own protection and cybersecurity measures, but also pay attention to that of their business and operational partners. While economic impact and real extent of third parties cybersecurity risks is hard to quantify, decision makers inevitably compare their decisions with other entities in their network. This paper presents a theoretically derived model to analyze the impact of social preferences and other factors on the willingness to cooperate in third party ecosystems. We hypothesize that willingness to cooperate among the organizations in the context of cybersecurity increases following the experience of cybersecurity attacks and increased perceived cybersecurity risks. The effects are mediated by perceived cybersecurity value and moderated by social preferences. These hypotheses are tested using a variance-based structural equation modeling analysis based on feedback from a sample of Norwegian organizations. Our empirical results confirm the strong positive impact of social preferences and cybersecurity attack experience on the willingness to cooperate, and support the reciprocal behavior of cybersecurity decision makers. We further show that more perception of cybersecurity risk and value deter the decision makers to cooperate with other organizations.

Journal of Lightwave Technology 37(13) s. 3138-3152 Doi: https://doi.org/10.1109/JLT.2019.2911651

In bufferless optical burst/packet switched (OBS/OPS) networks, data (bursts or packets) may be lost due to contention or equipment failure. Diversity coding-based path protection schemes can be used to protect data from a single-trunk failure with potentially more efficient resource utilization compared to dedicated (e.g., 1 + 1) path protection schemes and help reduce the burst/packet loss ratio. This paper provides a scalable and accurate burst/packet loss ratio approximation based on the Erlang fixed-point approximation for networks that employ protection based on diversity coding and for networks that employ protection based on both diversity coding and 1 + 1 path protection. We use discrete event simulations to assess the accuracy of the approximation based on a wide range of scenarios in a 10-node circular lattice and NSFNet networks. Further, we discuss the effect of parameter settings and the effect of the choice of the wavelength selection method on the accuracy of the approximation. We consider scenarios without wavelength conversion and with full wavelength conversion and two types of users: premium and regular. The premium users, typically of mission critical services, receive protection while the regular users do not. We compare diversity coding and 1 + 1 path protection in a 10-node circular lattice network. The results show that for this example network, for the premium users and under low traffic load, the burst/packet loss ratio in OBS/OPS networks is lower for diversity coding compared to 1 + 1 path protection. However, under heavy traffic load, we observe a lower loss ratio for the case of 1 + 1 path protection.

2019 IEEE European Symposium on Security and Privacy Workshops (EuroS&PW) s. 85-93 Doi: https://doi.org/10.1109/EuroSPW.2019.00016

Appropriate training is an effective solution to tackle the evolving threat landscape and conflicts in the cyber domain and to fulfill security requirements. Serious games demonstrate pedagogic effectiveness in this field, however, they need to comply with national, organizational, and individual strategies and characteristics. These games provide the players, individually or in groups, with an opportunity to develop their adversarial and system thinking skills to set up effective defenses. To this end, in this paper, we propose a framework for designing serious games that raise security awareness. The proposed framework considers the complex nature of the cyber domain, the knowledge and motivation of participants, and the experiential learning using cyber ranges. The framework is based on existing frameworks, and integrates their advantages to form a comprehensive framework. Future research should refine the framework and design serious games to evaluate its effectiveness in producing desired end results.

Social Science Research Network (SSRN) Doi: https://doi.org/10.2139/ssrn.3412902

Proceedings of the 2nd International Conference on E-commerce, E-Business and E-Government Doi: https://doi.org/10.1145/3234781.3234782

Network effects are one of the defining properties of the digital economy. It has been shown, both in theory and practice, that network effects contribute to the growth and potential success of businesses in the digital economy. In this paper, we present a quantitative case study of network effects in Facebook for the period 2011 to 2017. We estimate the value of Facebook, and analyse how this value depends on the number of Facebook users. Our results show that there are strong network effects in Facebook, as the value per user increases more than estimations obtained from Metcalfe's law. We also outline a general theory of the strength of network effects, and quantitatively estimate the strength of network effects in Facebook.

IEEE Transactions on Big Data 4(4) s. 516-529 Doi: https://doi.org/10.1109/TBDATA.2017.2749255

Minimum-Storage Regenerating (MSR) codes have emerged as a viable alternative to Reed-Solomon (RS) codes as they minimize the repair bandwidth while they are still optimal in terms of reliability and storage overhead. Although several MSR constructions exist, so far they have not been practically implemented mainly due to the big number of I/O operations. In this paper, we analyze high-rate MDS codes that are simultaneously optimized in terms of storage, reliability, I/O operations, and repair-bandwidth for single and multiple failures of the systematic nodes. The codes were recently introduced in [1] without any specific name. Due to the resemblance between the hashtag sign # and the procedure of the code construction, we call them in this paper HashTag Erasure Codes (HTECs) . HTECs provide the lowest data-read and data-transfer, and thus the lowest repair time for an arbitrary sub-packetization level α , where α≤r⌈k/r⌉ , among all existing MDS codes for distributed storage including MSR codes. The repair process is linear and highly parallel. Additionally, we show that HTECs are the first high-rate MDS codes that reduce the repair bandwidth for more than one failure. Practical implementations of HTECs in Hadoop release 3.0.0-alpha2 demonstrate their great potentials.

IEEE Photonics Technology Letters 28(15) s. 1688-1691 Doi: https://doi.org/10.1109/LPT.2016.2562676

IEEE International Conference on High Performance Switching and Routing, HPSR s. 61-68 Doi: https://doi.org/10.1109/HPSR.2016.7525640

IEEE (Institute of Electrical and Electronics Engineers)

IEEE Communications Letters 20(7) s. 1281-1284 Doi: https://doi.org/10.1109/LCOMM.2016.2561287

2016 9th International Symposium on Turbo Codes and Iterative Information Processing (ISTC) s. 280-284 Doi: https://doi.org/10.1109/ISTC.2016.7593121

We introduce a family of balanced locally repairable codes (BLRCs) [n, k, d] for arbitrary values of n, k and d. Similar to other locally repairable codes (LRCs), the presented codes are suitable for applications that require a low repair locality. The novelty that we introduce in our construction is that we relax the strict requirement the repair locality to be a fixed small number I, and we allow the repair locality to be either I or I + 1. This gives us the flexibility to construct BLRCs for arbitrary values of n and k which partially solves the open problem of finding a general construction of LRCs. Additionally, the relaxed locality criteria gives us an opportunity to search for BLRCs that have a low repair locality even when double failures occur. We use metrics such as a storage overhead, an average repair bandwidth, a Mean Time To Data Loss (MTTDL) and an update complexity to compare the performance of BLRCs with existing LRCs.

NIKT: Norsk IKT-konferanse for forskning og utdanning

IEEE Photonics Technology Letters 27(20) s. 2115-2118 Doi: https://doi.org/10.1109/LPT.2015.2453204

2015 IEEE Global Communications Conference (GLOBECOM) Doi: https://doi.org/10.1109/glocom.2015.7417372

IEEE International Conference on Communication, ICC 2015, Workshop Proceedings s. 680-685 Doi: https://doi.org/10.1109/ICCW.2015.7247260

2014 22nd Telecommunications Forum (TELFOR) s. 589-592 Doi: https://doi.org/10.1109/TELFOR.2014.7034478

We introduce a method that combines joint balanced source and network coding in optical packet-switched networks. It is an efficient way to combat packet loss that occurs due to contentions, to recover lost data due to link failures and to provide secure data transmission, i.e., secrecy. By using binary erasure codes and adding redundancy the destination is able to decode the source data when packet loss occurs. Coding at the intermediate node offers protection against single link failure. An eavesdropper cannot reconstruct the source data by eavesdropping a single link, since non-systematic coded packets are sent on disjoint paths.We also show that the proposed method has linear coding complexity, small header overhead and it does not require sending a feedback for each packet.

Computer Networks Doi: https://doi.org/10.1016/j.comnet.2014.07.009

Advances in Intelligent Systems and Computing 231 s. 283-289 Doi: https://doi.org/10.1007/978-3-319-01466-1_27

17th International Conference on Optical Networking Design and Modeling s. 88-93 Doi: https://doi.org/10.1016/j.comcom.2004.12.002

17th International Conference on Optical Networking Design and Modeling

Lecture Notes in Computer Science (LNCS) 8115 s. 161-172 Doi: https://doi.org/10.1007/978-3-642-40552-5_15

Simulation modelling practice and theory 31 s. 132-148 Doi: https://doi.org/10.1016/j.simpat.2012.10.010

Computer Networks 57(9) s. 1974-1990 Doi: https://doi.org/10.1016/j.comnet.2013.03.015

International Journal of Advanced Computer Science and Applications (IJACSA) 4(12) s. 202-211 Doi: https://doi.org/10.14569/IJACSA.2013.041230

Proceedings of World Telecommunications Congress

Proceedings 17th European Conference on network and Optical Communication, June 20-22, 2012, Catalonia Spain Doi: https://doi.org/10.1109/noc.2012.6249934

2012 IEEE Global Telecommunications Conference -GLOBECOM 2012 s. 2882-2888 Doi: https://doi.org/10.1109/GLOCOM.2012.6503554

16th International Conference on Optical Network Design and Modeling (ONDM), 2012 Doi: https://doi.org/10.1109/ondm.2012.6210178

Proceedings of World Telecommunications Congress

IEEE International Conference on Communications Doi: https://doi.org/10.1109/icc.2012.6363928

NIKT: Norsk IKT-konferanse for forskning og utdanning

International Conference on Transparent Optical Networks (ICTON) Doi: https://doi.org/10.1109/icton.2011.5971141

IET Communications 4(3) s. 334-342 Doi: https://doi.org/10.1049/iet-com.2009.0295

Proceedings of the 5th advanced international conference on telecommunications s. 381-388

Proceedings of the international conference on photonics and switching 2009

IEEE Global Communications Conference, Exhibition, & Industry Forum (GLOBECOM) Doi: https://doi.org/10.1109/GLOCOM.2009.5426312

Journal of Optical Networking 7(4) s. 294-309

Photonic network communications 13(2) s. 183-194 Doi: https://doi.org/10.1007/s11107-006-0036-z

11th International IFIP TC6 Conference, ONDM 2007 s. 146-155

Computer Communications 30(6) s. 1229-1243 Doi: https://doi.org/10.1016/j.comcom.2006.12.005

Proceedings of the 11th European Conference on Networks and Optical Communications s. 512-518

Journal of Optical Networking 5(10) s. 747-763

Proceedings of the 10th Conference on Optical Network Design and Modelling

Proceedings of the 11th European Conference on Networks and Optical Communications s. 519-526

Proceedings of the Advanced International Conference on Telecommunications (AICT'06)

Proceedings of the Advanced International Conference on Telecommunications (AICT'06)

Proceedings of the 10th Conference on Optical Network Design and Modelling

proceedings of the 32th European Conference on Optical Communications s. 407-408

Proceedings of the 8th International Conference on Transparent Optical Networks, volume 3

IEEE Communications Magazine 44(8) s. 52-57

Proceedings of the Advanced International Conference on Telecommunications (AICT'06)

Wireless Networks - The Journal of Mobile Communication, Computation and Information 12(3) s. 383-394

Proceedings of the 7th International Conference on Transparent Optical networks (ICTON) in Barcelona, Vol. 1 s. 385-388

Proceedings of the 7th International Conference on Transparent Optical networks (ICTON) in Barcelona, Vol. 1 s. 62-66

Optics Express 13(5) s. 1685-1695 Doi: https://doi.org/10.1364/OPEX.13.001685

Stochastic processes have been widely employed in order to assess the network layer performance of Optical Packet Switched (OPS) networks. In this paper we consider how the Engset traffic model may be applied to evaluate the blocking probability in asynchronous bufferless OPS networks. We present two types of the Engset traffic model, i.e. the Engset lost calls cleared traffic model and the Engset overflow traffic model. For both traffic models, the time-, call-, and traffic congestion are derived. A numerical study shows that the observed blocking probability is dependent on the choice of traffic model and performance metric.

Computer Communications 28

Proceedings of the 7th International Conference on Transparent Optical networks (ICTON) in Barcelona, Vol. 1 s. 85-90

IEEE Photonics Technology Letters 17(11) s. 2469-2471

31st European Conference on Optical Communications - ECOC 2005 - Proceedings s. 695-696

Norsk veterinærtidsskrift 116(7) s. 531-535

I perioden 1976-2000 ble det utført i alt 1898 medikamentelle immobiliseringer av viltlevende elg i Norge. Tretten dyr(0,7 ? døde eller måtte avlives i tilslutning til innfangingen. Anbefalt metode for immobilisering av viltlevende elg i Norge er administrasjon av etorfin ved hjelp av injeksjonsvåpenfra helikopter på snødekt mark. Risikoen for mortalitet ved denne metoden er meget liten: kun åtte dyr (0,5 ? døde av i alt 1526 immobiliseringer foretatt fra 1984 til 2004. Dødsårsaker var drukning (én voksen ku og én voksen okse), respirasjonsstans etter intravaskulær injeksjon (én voksen ku), skade iryggmargen forårsaket av injeksjonspilen (én avmagret kalv med beinskjørhet og parasittær lungebetennelse) og respirasjonsstans forårsaket av en relativ overdosering (fire kalver i dårlig kondisjon). Standard dose for etorfin er 7,50 ? 9,00mg/voksen og 3,75 ?4,50 mg/kalv. Dyr som ikke har lagt seg innenti minutter etter første injeksjon, kan påskytes på nyttmed full dose. A total of 1,898 chemical immobilizations of free-rangingmoose (Alces alces) were carried out in Norway from 1976 to 2004. Thirteen animals (0.7 ? died or were euthanized. The recommended method for immobilization of free-ranging moose inNorway is darting from a helicopter with etorphine on snow-covered ground. The risk of mortality with this method is verylow, only eight animals (0.5 ? died during 1,526 captures from 1984 to 2004. Causes of mortality were drowning in one adult female and one adult male, respiratory arrest due to intravascular injection in an adult female, traumatic spinal lesions due to dart impact in the lumbar region in a cachectic calf with osteoporosis and verminous pneumonia, and respiratoryarrest due to relative overdosing in four calves in poor body condition. The standard doses of etorphine are 7.5-9.0 mg/animal in adults and 3.75-4.50 mg/animal in calves. Animals which are not down within ten minutes after initial darting canbe redarted with a full dose.

Optics Express 12(3) s. 410-415 Doi: https://doi.org/10.1364/OPEX.12.000410

Service differentiation is a crucial issue in the next-generation Optical Packet Switched networks. In this paper we examine how bursty traffic influences the performance of a service differentiated Optical Packet Switched network. By using time-continuous Markov chains, we derive explicit results for the packet loss rates in the case of a bursty hyper-exponential arrival process. Results indicate that the performance is degraded as the burstiness of the arrival process increases.

Chinese Optics Letters (COL) 2(3) s. 131-134

In this paper we present an analytical model, which considers the effects of the switching time on the network performance in service differentiated Optical Packet/Burst Switched networks (OPS/OBS). Our results indicate that the switching time must be less than 10 % of the packet/burst duration in order to avoid any significant reductions in the network performance. Furthermore, regarding a network with full wavelength conversion, we show that the benefits of statistical resource sharing are almost non-existent for low priority traffic when the switching time is large.

Journal of Optical Networking 3(12) s. 866-866

Telecommunications Systems 27(2-4) s. 151-179

Optical Packet Switching (OPS) is a promising technology for future core networks due to the ability to handle bursty traffic, adaptability to changes in the network infrastructure and good network utilization. In order to provide sufficient Quality of Service (QoS) to the emerging range of real-time and critical business applications, service differentiation should be present in future OPS. This paper presents the Preemptive Drop Policy (PDP), which provides service differentiation in asynchronous bufferless OPS. Based on time-continuous Markov chains, we introduce an analytical model of the PDP for switches with and without wavelength conversion. We extend the PDP into the Adaptive PDP (APDP), which provides absolute QoS guarantees in OPS. Simulations performed validate our analytical model and show that the APDP operates properly in a dynamic changing system load scenario.

Optics Express 12(20) s. 4881-4895 Doi: https://doi.org/10.1364/OPEX.12.004881

A crucial issue in optical packet switched (OPS) networks is packet losses at the network layer caused by contentions. This paper presents the network layer packet redundancy scheme (NLPRS), which is a novel approach to reduce the end-to-end data packet loss rate in OPS networks. By introducing redundancy packets in the OPS network, the NLPRS enables a possible reconstruction of data packets that are lost due to contentions. An analytical model of the NLPRS based on reduced load Erlang fix-point analysis is presented. Simulations of an OPS ring network show that the NLPRS is in particular efficient in small networks operating at low system loads. Results also show how the arrival process, packet length distribution, network size and redundancy packet scheduling mechanism influence the NLPRS performance.