Resilient virtual topologies in optical networks and clouds

Optical networks play a crucial role in the development of Internet by providing a high speed infrastructure to cope with the rapid expansion of high bandwidth demand applications such as video, HDTV, teleconferencing, cloud computing, and so on. Network virtualization has been proposed as a key enabler for the next generation networks and the future Internet because it allows diversification the underlying architecture of Internet and lets multiple heterogeneous network architectures coexist. Physical network failures often come from natural disasters or human errors, and thus cannot be fully avoided. Today, with the increase of network traffic and the popularity of virtualization and cloud computing, due to the sharing nature of network virtualization, one single failure in the underlying physical network can affect thousands of customers and cost millions of dollars in revenue. Providing resilience for virtual network topology over optical network infrastructure thus becomes of prime importance. This thesis focuses on resilient virtual topologies in optical networks and cloud computing. We aim at finding more scalable models to solve the problem of designing survivable logical topologies for more realistic and meaningful network instances while meeting the requirements on bandwidth, security, as well as other quality of service such as recovery time. To address the scalability issue, we present a model based on a column generation decomposition. We apply the cutset theorem with a decomposition framework and lazy constraints. We are able to solve for much larger network instances than the ones in literature. We extend the model to address the survivability problem in the context of optical networks where the characteristics of optical networks such as lightpaths and wavelength continuity and traffic grooming are taken into account. We analyze and compare the bandwidth requirement between the two main approaches in providing resiliency for logical topologies. In the first approach, called optical protection, the resilient mechanism is provided by the optical layer. In the second one, called logical restoration, the resilient mechanism is done at the virtual layer. Next, we extend the survivability problem into the context of cloud computing where the major complexity arises from the anycast principle. We are able to solve the problem for much larger network instances than in the previous studies. Moreover, our model is more comprehensive that takes into account other QoS criteria, such that recovery time and delay requirement

Models of vertical interconnection in the future internet networks

Interkonekcija, čiji primarni cilj je omogućavanje korisnicima jednog učesnika na tržištu telekomunikacija da komuniciraju sa korisnicima drugog učesnika, odnosno, obezbeđivanje pristupa servisima koje obezbeđuje drugi učesnik, javila se nakon liberalizacije tržišta telekomunikacija. Vertikalna interkonekcija predstavlja fizičko i logičko povezivanje učesnika na različitim nivoima mreže. U okruženju budućeg Interneta, sagledavanje tehničko-ekonomskih aspekata interkonekcije predstavlja pitanje od izuzetnog značaja. U opštem slučaju, učesnici u vertikalnoj interkonekciji u okruženju budućeg Interneta mogu biti provajderi sadržaja i aplikacija, provajderi Internet servisa, Content Delivery Network (CDN) provajderi i cloud provajderi. Pojava Cloud Computing-a uvela je značajne promene u Internet okruženju koje se pre svega odnose na mogućnost pristupa skalabilnim i deljivim, fizičkim ili virtuelnim resursima. Na taj način, stvara se elastična platforma koja obezbeđuje dinamičnu i jednostavnu skalabilnost, pojednostavljuje se obezbeđivanje infrastrukture i omogućava se unapređenje performansi. Razvoj servisa i aplikacija zahtevnih u pogledu propusnog opsega praćen širom implementacijom Cloud Computing-a utiče na kontinuiran rast Internet saobraćaja, što zahteva primenu tehnologija koje mogu zadovoljiti sve strože zahteve. Kao rešenje za transportni nivo mreže, razvijene su elastične optičke mreže koje mogu obezbediti dovoljne propusne opsege uz efikasno iskorišćenje spektra. Imajući u vidu promene koje prate razvoj okruženja budućeg Interneta, kao i značaj vertikalne interkonekcije, neophodno je razmotriti i jasno definisati tehničko-ekonomske relacije između učesnika u budućem Internetu, što je predmet istraživanja ove doktorske disertacije. U okviru disertacije predložen je model koji ima za cilj određivanje adekvatnog ugovora o interkonekciji između učesnika u vertikalnoj interkonekciji, i to provajdera sadržaja i aplikacija i provajdera Internet servisa u procesu obezbeđivanja sadržaja krajnjim korisnicima, uz mogućnost parcijalne migracije sadržaja na resurse cloud provajdera. Analiza obuhvata različite ugovore o interkonekciji i određuje adekvatan ugovor, u zavisnosti od ciljnih profita provajdera koji učestvuju u vertikalnoj interkonekciji i prihvatljive stope odbijenih zahteva za obezbeđivanje sadržaja krajnjim korisnicima. Data analiza je proširena istraživanjem adekvatnog mehanizma tarifiranja i alokacije resursa cloud provajdera. Predložen je nov, hibridni model pristupa resursima cloud provajdera koji obezbeđuje zadovoljavajuće rezultate u kontekstu minimizacije troškova i minimizacije stope odbijenih zahteva za pristup sadržajima...Interconnection, whose primary aim is enabling communication between end users of different undertakings, i.e. enabling access to the other undertaking's services, was introduced after the telecommunication market liberalization. Vertical interconnection represents the physical and logical linking of the undertakings on different network levels. Consideration of technical and economic aspects of the interconnection is a crucial issue in the future Internet environment. In general, undertakings in vertical interconnection in the future Internet environment include content and application providers, Internet service providers, Content Delivery Network (CDN) providers and Cloud providers. The development of Cloud Computing introduced significant changes in the Internet environment in terms of enabling access to scalable and shareable, physical or virtual resources. Therefore, the elastic platform for dynamic and simple scalability is enabled, the access to infrastructure is simplified and performances are improved. High bandwidth demanding services and applications, along with the wide adoption of Cloud Computing causes permanent growth of Internet traffic. This indicates that the introduction of new technologies, capable to satisfy high bandwidth requirements, is necessary. Elastic optical networks are proposed as a promising solution for transport networks. These networks provide enough bandwidth, along with high efficiency in spectrum utilization. Forasmuch changes in the future Internet environment and the importance of the vertical interconnection, it is mandatory to consider and properly define technical and economic relations between undertakings in the future Internet environment, which is the research subject of this doctoral dissertation. Within dissertation, a model for the determination of a proper interconnection agreement between undertakings in the vertical interconnection, content and application provider and an Internet service provider, in the content provisioning process with partial cloud migration is proposed. The analysis comprises different interconnection agreements and determines appropriate agreement, depending on the targeted providers' profits and satisfying requests' for content provisioning rejection rate. This analysis is extended to determine adequate pricing and allocation mechanism for cloud provider's resources. A new, hybrid model for enabling access to cloud resources is proposed. The model provides satisfying results in terms of the costs' minimization and the minimization of requests' rejection rate..

Towards Zero Touch Next Generation Network Management

The current trend in user services places an ever-growing demand for higher data rates, near-real-time latencies, and near-perfect quality of service. To meet such demands, fundamental changes were made to the front and mid-haul and backbone networking segments servicing them. One of the main changes made was virtualizing the networking components to allow for faster deployment and reconfiguration when needed. However, adopting such technologies poses several challenges, such as improving the performance and efficiency of these systems by properly orchestrating the services to the ideal edge device. A second challenge is ensuring the backbone optical networking maximizes and maintains the throughput levels under more dynamically variant conditions. A third challenge is addressing the limitation of placement techniques in O-RAN. In this thesis, we propose using various optimization modeling and machine learning techniques in three segments of network systems towards lowering the need for human intervention targeting zero-touch networking. In particular, the first part of the thesis applies optimization modeling, heuristics, and segmentation to improve the locally driven orchestration techniques, which are used to place demands on edge devices throughput to ensure efficient and resilient placement decisions. The second part of the thesis proposes using reinforcement learning (RL) techniques on a nodal base to address the dynamic nature of demands within an optical networking paradigm. The RL techniques ensure blocking rates are kept to a minimum by tailoring the agents’ behavior based on each node\u27s demand intake throughout the day. The third part of the thesis proposes using transfer learning augmented reinforcement learning to drive a network slicing-based solution in O-RAN to address the stringent and divergent demands of 5G applications. The main contributions of the thesis consist of three broad parts. The first is developing optimal and heuristic orchestration algorithms that improve demands’ performance and reliability in an edge computing environment. The second is using reinforcement learning to determine the appropriate spectral placement for demands within isolated optical paths, ensuring lower fragmentation and better throughput utilization. The third is developing a heuristic controlled transfer learning augmented reinforcement learning network slicing in an O-RAN environment. Hence, ensuring improved reliability while maintaining lower complexity than traditional placement techniques

A new model for developing capacity expansion strategies

Nove širokopojasne tehnologije i stalno rastući obim saobraćaja imaju veliki uticaj na upravljanje infrastrukturnim kapacitetima telekomunikacione mreže. Efikasno planiranje mrežnih resursa nije moguće realizovati bez primene pouzdanih modela za prognoziranje tražnje, kao i precizno odabranih veličina za karakterizaciju saobraćaja. U tom smislu, osnovni predmet istraživanja ove doktorske disertacije su strategije proširenja mrežnih resursa, koje se oslanjaju na primenu različitih metoda planiranja telekomunikacionih mreža, sa ciljem određivanja optimalnog vremena za realizaciju proširenja. Predloženi modeli proširenja resursa mreže baziraju se na optimizaciji perioda proširenja resursa mreže uz minimizaciju troškova zagušenja i troškova neophodne opreme, pri čemu se ulazni podaci oslanjaju na prognozirane vrednosti tražnje na telekomunikacionom tržištu. Mogućnosti primene različitih metoda planiranja, u kontekstu strategije proširenja mrežnih resursa, razmatrane su na hipotetičkoj WDM mreži, sa koegzistencijom fiksnih i fleksibilnih grid tehnologija. U disertaciji su razmatrani suprotstavljeni zahtevi investicionih ulaganja u cilju brzog povraćaja uloženih sredstava i kvaliteta opsluživanja korisnika. Kompromisno rešenje predstavlja i novi pristup, predložen u disertaciji, koji se odnosi na izbor parametara za karakterizaciju mrežnog saobraćaja, sa ciljem smanjenja uticaja neizvesnosti prognoziranih podataka na odluku o proširenju kapaciteta. U tom smislu, izvršena je analiza, na osnovu koje je utvrđeno da se, poređenjem vrednosti nivoa penala funkcije troškova zagušenja, sa jedne strane i vrednosti parametra Verovatnoće blokiranja kapaciteta, sa druge, može odrediti optimalni vremenski period za sprovođenje odluke o migraciji tehnologija, u posmatranom slučaju. Među najvažnijim naučnim doprinosima disertacije, mogu se izdvojiti implementacija prognoziranih vrednosti saobraćajnih zahteva, zasnovana na primeni teorije difuzionih modela, novi optimizacioni model, kao modifikacija modela strategije serijskog proširenja kapaciteta mrežnog linka, u kojem se uvodi mogućnost prelaska na novu tehnologiju, kao i novi pristup za smanjenje uticaja neizvesnosti prognoziranih podataka na određenu odluku o proširenju kapaciteta, zasnovan na izboru parametara za karakterizaciju mrežnog saobraćaja.New broadband services and ever-increasing Internet traffic volumes have a major influence on the backbone infrastructure capacity management, raising the importance of efficient planning of network resources, based on demand forecast and the appropriate selection of traffic characterization parameters, as well. Therefore, the main subject of the research, presented in the doctoral thesis are the network resources expansion strategies, with respect of different telecommunication network planning methods. Relaying on the forecasted demand in the telecommunications market, the proposed models are used in order to determine the optimal times for network capacity expansion and the technology migration, by minimizing the equipment and congestion costs. Application of different planning methods, in the context of the network resource expansion strategies, has been considered within the hypothetical WDM network, with the coexistence of fixed and flexible grid technologies. Having in mind the contrast between network performance improvement and the investors’ interest for the longer operation of already built-in technologies, a novel approach has been proposed in order to determine the appropriate time for making the technology migration. In this sense, the traffic characterization parameters (the Penalty function and the Bandwidth Blocking Ratio) were used. The main innovative aspect of the approach proposed in the thesis considers the combination of these two metrics in order to decrease uncertainty of the forecasted demands. The other important scientific contributions of the dissertation are the traffic demand forecasting approach based on the diffusion model theory, as well as the novel multiperiod network capacity expansion model, which introduces the option of the migration to the new technology