@article{MTMT:2669470, title = {Evaluation and estimation of the availability of p-cycle protected connections}, url = {https://m2.mtmt.hu/api/publication/2669470}, author = {Szigeti, János and Cinkler, Tibor}, doi = {10.1007/s11235-011-9576-3}, journal-iso = {TELECOMMUN SYST}, journal = {TELECOMMUNICATION SYSTEMS}, volume = {52}, unique-id = {2669470}, issn = {1018-4864}, year = {2013}, eissn = {1572-9451}, pages = {767-782} } @CONFERENCE{MTMT:2694730, title = {Benchmarking of GPS sources for generating traffic information}, url = {https://m2.mtmt.hu/api/publication/2694730}, author = {Szigeti, János and Gordos, Géza and Laborczi, Péter}, booktitle = {16th ITS World Congress and Exhibition on Intelligent Transport Systems and Services}, unique-id = {2694730}, year = {2011}, pages = {1-7} } @CONFERENCE{MTMT:2662395, title = {Inaccuracy of the Serial-Parallel Availability Estimation Method}, url = {https://m2.mtmt.hu/api/publication/2662395}, author = {Szigeti, János and Cinkler, Tibor}, booktitle = {RNDM 2010 - 2nd International Worskhop on Reliable Networks Design and Modeling}, doi = {10.1109/ICUMT.2010.5676573}, unique-id = {2662395}, abstract = {Provisioning QoS network connections with the desired availability relies on estimating the availability of the connections in advance. The redundancy of the protection - which denotes how many failures can be survived - gives a good hint on the availability, thus lower bound estimation can be carried out. If we want to achieve a more accurate approximation, we have to use other methods. The Serial-Parallel availability modeling and calculation method, based on the availability metrics of the components of the connection, offers a fast estimation, with the complexity of O(n) in case of n components. However, the result of this estimation can be inaccurate since the model does not take into account the overlapping of components, i.e., when a component is member of more different series. In this paper we analyze the inaccuracy of the Serial-Parallel method. We prove that the estimated availability is always less than the exact one, define an upper bound onto the inaccuracy of the estimated unavailability and show where does this inaccuracy converge by increasing the availability of the network components.}, year = {2010}, pages = {615-621} } @article{MTMT:32643781, title = {P-cycle Protection in multi-domain optical networks}, url = {https://m2.mtmt.hu/api/publication/32643781}, author = {Szigeti, János and Romeral, R. and Cinkler, Tibor and Larrabeiti, D.}, doi = {10.1007/s11107-008-0141-2}, journal-iso = {PHOTONIC NETW COMMUN}, journal = {PHOTONIC NETWORK COMMUNICATIONS}, volume = {17}, unique-id = {32643781}, issn = {1387-974X}, abstract = {Providing resilient inter-domain connections in multi-domain optical GMPLS networks is a challenge. On the one hand, the integration of different GMPLS domains to run traffic engineering operations requires the development of a framework for inter-domain routing and control of connections, while keeping the internal structure and available resources of the domains undisclosed to the other operators. On the other hand, the definition of mechanisms to take advantage of such automatically switched inter-domain connectivity is still an open issue. This article focuses on the analysis of applicability of one of these mechanisms: P-cycle-based protection. The proposed solution is based on the decomposition of the multi-domain resilience problem into two sub-problems, namely, the higher level inter-domain protection and the lower level intra-domain protection. Building a P-cycle at the higher level is accomplished by certain tasks at the lower level, including straddling link connection, capacity allocation and path selection. In this article, we present several methods to realize inter-domain P-cycle protection at both levels and we evaluate their performance in terms of availability and spent resources. A discussion on a proposal of implementation of signalling based on extensions of existing protocols such as RSVP-TE and the PCE architecture illustrates the practical viability of the approach. © 2008 Springer Science+Business Media, LLC.}, keywords = {Computer networks; Optical data processing; Network architecture; Fiber optic networks; RESILIENCE; RESILIENCE; Do-mains; multi-domain networks; multi-domain networks; One hands; P-cycle; P-cycle; Optical Networks; Path selections; Capacity allocations; GMPLS networks; Internal structures; Rsvp-te; Traffic engineerings}, year = {2009}, eissn = {1572-8188}, pages = {35-47} } @CONFERENCE{MTMT:2669469, title = {Benchmarking of Floating Car Data Sources}, url = {https://m2.mtmt.hu/api/publication/2669469}, author = {Szigeti, János and Laborczi, Péter and Gordos, Géza}, booktitle = {16th ITS World Congress and Exhibition on Intelligent Transport Systems and Services}, unique-id = {2669469}, abstract = {Most Floating Car Data (FCD) systems use data of fleet management companies to monitor the currents state of traffic. However, the original task of these systems (e.g., tracking positions and status of taxis or protecting vehicles) are different from measuring travel times. Consequently, it is important to measure the ``quality'' of a given fleet from the Floating Car Data point of view. Usually, the number of vehicles and the mean time between two measurements is used to assess the quality of the data but these numbers are misleading in many cases. Other approach would be to carry out the whole process until travel time estimation and compare the resulting travel times with other sources. This process is very time consuming and cannot be carried out because of lack of data in most cases. FCD source benchmarking method -- proposed in this paper -- is a simple way of estimating, monitoring and comparison of different data sources. The inputs of the method are the data sets only, not even the digital map is needed. The method proved to be efficient in a Floating Car Data project in Budapest.}, year = {2009} } @article{MTMT:2645131, title = {Optical core networks research in the e-photon-one project}, url = {https://m2.mtmt.hu/api/publication/2645131}, author = {Callegati, Franco and Cugini, Filippo and Ghobril, Paul and Gunreben, Sebastian and López, V and Martini, Barbara and Marińo, Pablo Pavón and Perényi, Marcell Ádám and Szigeti, János and Segovia, Juan and Staessens, Dimitri and Sengezer, Namik and Tornatore, Massimo}, doi = {10.1109/JLT.2009.2024090}, journal-iso = {J LIGHTWAVE TECHNOL}, journal = {JOURNAL OF LIGHTWAVE TECHNOLOGY}, volume = {27}, unique-id = {2645131}, issn = {0733-8724}, abstract = {This paper reports a summary of the joint research activities on Optical Core Networks within the e-Photon-ONe project. It provides a reasonable overview of the topics considered of interest by the European research community and supports the idea of building joint research activities that can leverage on the expertise of different research groups.}, year = {2009}, eissn = {1558-2213}, pages = {4415-4423} } @inproceedings{MTMT:2639327, title = {Rule-Based Topology Advertisement Supporting Generalized Protection}, url = {https://m2.mtmt.hu/api/publication/2639327}, author = {Szigeti, János and Cinkler, Tibor and Romeral, Ricardo}, booktitle = {ONDM}, unique-id = {2639327}, abstract = {Routing in multilayer optical networks can be made efficient if Label Switched Paths are searched in a Wavelength Graph that represents the state and the switching facilities of the network devices very accurately. Maintaining the Wavelength Graph by using the conventional Link State Advertisement control mechanism leads to scalability problem. Much of the link state information is, however, redundant as the set of state changes triggered by a single resource allocation or release are in correlation. By introducing a rule-based topology advertisement and maintenance method, the amount of control messages can be significantly reduced without deteriorating the quality of routing. This paper proposes an extension to the method to be able to handle various protection schemes in the network simultaneously. Although the proposed method is primarily developed for optical networks and Wavelength Graphs it can be applied efficiently also onto pure MPLS networks.}, year = {2009}, pages = {129-135} } @inproceedings{MTMT:2618027, title = {Adaptive Multi-Layer Traffic Engineering with Shared Risk Group Protection}, url = {https://m2.mtmt.hu/api/publication/2618027}, author = {Cinkler, Tibor and Hegyi, Péter and Geleji, Géza and Szigeti, János and Ladányi, Ákos}, booktitle = {2008 IEEE International Conference on Communications, Vols 1-13}, doi = {10.1109/ICC.2008.1006}, unique-id = {2618027}, year = {2008}, pages = {5367-5371}, orcid-numbers = {Hegyi, Péter/0000-0003-2384-8576; Ladányi, Ákos/0000-0002-3974-0722} } @article{MTMT:1789125, title = {Multidomain shared protection with limited information via MPP and p-cycles}, url = {https://m2.mtmt.hu/api/publication/1789125}, author = {Szigeti, János and Gyarmati, László and Cinkler, Tibor}, doi = {10.1364/JON.7.000400}, journal-iso = {J OPT NETW}, journal = {JOURNAL OF OPTICAL NETWORKING}, volume = {7}, unique-id = {1789125}, issn = {1536-5379}, abstract = {The internet consists of a collection of more than 21,000 domains called autonomous systems operated mostly under different authorities (operators?providers) that, although they cooperate over different geographical areas, compete in a country or other area. Recently, the path computation element concept has been proposed to generalized multiprotocol label switching controlled optical board networks to make routing decisions for interdomain connections taking into account traffic engineering, quality of service and resilience considerations. Still the question of protection shareability emerges. For dedicated protection it is enough to know the topology of the network to be able to calculate disjoint paths. However, to reduce network resource usage by sharing of protection resources (e.g., end-to-end shared protection) it is also mandatory to know the exact working and protection path pairs for all the demands. This can be checked within a domain where not only the full topology and link-state information is flooded but also the working and protection paths are known for each connection; however; over the domain boundaries for security and scalability reasons no such information is being spread. We propose using two techniques that do not require flooding the information on working and protection paths while still allowing the sharing of resources. These two techniques are the multidomain p-cycles and the multidomain multipath routing with protection. After explaining the principles of these methods we evaluate the trade-off between the resource requirement and availability of these techniques by simulations.}, year = {2008}, pages = {400-409} } @inproceedings{MTMT:32643789, title = {Incremental availability evaluation model for p-cycle protected connections}, url = {https://m2.mtmt.hu/api/publication/32643789}, author = {Szigeti, János and Cinkler, Tibor}, booktitle = {DRCN 2007, 6th International Workshop on the Design of Reliable Communication Networks}, doi = {10.1109/DRCN.2007.4762278}, unique-id = {32643789}, abstract = {QoS routes need availability assurance. Regardless of the applied protection scheme, there are several heuristic algorithms that can approximate the availability of connections based on the availability parameters of network components along the connection path. Accurate approximation can be achieved with simple and fast calculation only for the most basic protection schemes, the more complex the protection scheme is the more complex and long running calculation is required to get the result. Though, the inaccuracy of the heuristic algorithms is negligible in the most cases of practical usage. In this paper we present an availability calculation method for p-cycles that exploits the special properties of the p-cycle protection scheme and provides accurate results without enumerating all the possible network or protection configuration states. The method evaluates the availability of the connection along the working path link-by-link incrementally, pre-calculating also those conditional availabilities of the connection-part that may be used in latter calculations. Theoretically, the complexity of the algorithm is still O(2n), however, in fact n does not get high, moreover, it can be kept moderate low if the size of the cycles is constrained.}, keywords = {Heuristic methods; Portals; Large scale systems; Availability; Telecommunication networks; Heuristic algorithms; Calculation methods; Special properties; P-cycle; conditional probability; Evaluation models; protection schemes; P-cycle protections; Working paths}, year = {2007} }