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EN
This research began when observations were made on any-to-any-connection services that require QoS (Quality of Service) and tunnel measurements. Tunnel is a technique to interconnect between local networks that are separated through a public network. Research questions found looping caused by traffic issues when sending data in the MPLS service layer-2 tunneling service. Furthermore, this research hypothesis proposes optimizing QoS performance in the application of the SR-TE (Segment Routing-Traffic Engineering) method in the MPLS (Multi-Protocol Label Switching) network and analyzing traffic based on MAC addresses using the looping-protection method. This research contributes to optimizing the MPLS network and is a recommended solution for simplifying control-plane operation, especially the SR-TE method and looping-protection in the L2- VPN MPLS service. The purpose of this study is to analyze the performance of MPLS networks, as well as analyze the application of L2-VPN (Layer 2 Virtual Private Network) MPLS networks. The targeted TKT (Technology Readiness Level) is 3rd-Level, which is an analytical and experimental proof of the MPLS tunnel network model on Layer-2 VPN services. The results of the research concluded that testing the SR-TE method is a solution to simplify the process of labeling data traffic that is global labelling, then the looping-protection method is a solution to eliminate looping indications. The QoS obtained has also shown an "excellent" category based on TIPHON standards.
PL
W artykule krótko scharakteryzowano technologie w sieciach pierścieniowych oraz właściwości techniki MPLS. Przeprowadzono analizę możliwości implementacji i weryfikacji procedur zestawiania ścieżek LSP w sieci dostępowej MPLS o topologii pierścieniowej.
EN
The article briefly describes technologies in ring networks and the properties of the MPLS technique. An analysis of the possibility of implementing and verifying the procedures for setting up LSP paths in the MPLS access network with ring topology was performed.
PL
Technologia Wieloprotokołowej Komutacji Etykietowej (MPLS – MultiProtocol Label Switching) dostarcza odpowiednie mechanizmy wspierające proces zachowania jakości usług, jednak wymaga nadrzędnego elementu sterującego. Takim elementem może być kontroler zrealizowany w koncepcji Sieci Definiowanych Programowo (SDN – Software Defined Networking), wprowadzający abstrakcję, rozdzielającą płaszczyznę przekazywania od płaszczyzny sterowania. W niniejszym artykule przedstawiono sposób połączenia obu technologii w ramach jednej sieci wielodomenowej.
EN
Multiprotocol Label Switching (MPLS) provides appropriate mechanisms to support the process of maintaining the quality of services. However, it requires a superior control element. Such an element may be a controller implemented according to Software Defined Networking concept, introducing abstraction that separates the forwarding plane from the control plane. This article presents the method of combining both technologies within one multi-domain network.
PL
Sieci sterowane programowo (SDN, Software- Defined Networks) są obecnie wdrażane już nie tylko w sieciach laboratoryjnych czy też kampusowych, ale także w rozległych sieciach operatorskich oraz centrach danych. Jednakże rozwiązanie to, pierwotnie zaprojektowane dla sieci kampusowych, cechuje się problemami ze skalowalnością (w szczególności, gdy wykorzystywany jest protokół OpenFlow). W niniejszym artykule zaproponowano nowe metody wyboru wag łączy umożliwiające realizację transmisji wielościeżkowej z agregacją przepływów dla sieci SDN. Mechanizm ten pozwala także na znaczne ograniczenie liczby wymienianych pakietów sygnalizacyjnych.
EN
Nowadays, Software-Defined Networks (SDN) are in the phase of deployment not only in laboratories or campus networks, but also in ISPs and data center networks. Due to fact that SDNs were primarily designed for campus networks, they face some scalability issues (especially when OpenFlow is used). In this article, new methods of link weight selection providing multipath transmission together with flow aggregation are proposed. Moreover, the presented mechanism significantly reduces communication between the controler and switches.
PL
Koncepcja sieci sterowanych programowo (SDN - Software-Defined Networking) wzbudziła wielkie zainteresowanie zarówno środowiska naukowego, jak i producentów sprzętu telekomunikacyjnego oraz operatorów. Duże sieci implementujące tę koncepcję zderzyły się z problemem ograniczonej wielkości tablic przepływów w urządzeniach przełączających. W artykule przedstawiono mechanizm umożliwiający redukcję liczby przepływów instalowanych w tablicach przełączników szkieletowych sieci. Dzięki zastosowaniu procedury agregacji przepływów korzystającej z centralnie sterowanej dystrybucji etykiet MPLS osiągnięto znaczną redukcję liczby wpisów. Ponadto, proponowany mechanizm oparty na równoczesnej transmisji wielościeżkowej umożliwia efektywne wykorzystanie dostępnych zasobów.
EN
Software-Defined Networking (SDN) concept has been attracting interest of the research community and vendors/operators. Huge networks implementing SDNbased solutions have faced a problem of limited sizes of flow tables in switches. The paper presents a mechanism enabling reduction of flow entries in the core switches. Thanks to implementation of a flow aggregation procedure, based on introduction of centrally managed MPLS label distribution done by SDN controller, significant reduction of flow entries has been obtained. Moreover, the proposed mechanism delivers a concurrent multipath transmission optimally utilizing available resources.
PL
W artykule przedstawiono technologię MPLS (ang. MultiProtocol Label Switching), która reprezentuje nowy poziom w rozwoju standardów wykorzystywanych w połączeniach technologii przełączania warstwy drugiej modelu odniesienia ISO/OSI z technologią routingu w warstwie trzeciej. Podstawowym celem procesu standaryzacyjnego MPLS jest stworzenie elastycznej struktury sieci, która będzie posiadała dużo większą efektywność niż dotychczasowe systemy sieci oraz będzie w dużo większym stopniu skalowalna. Analizując wyniki otrzymane w badaniach symulacyjnych, można stwierdzić, iż zastosowanie sieci MPLS jest w stanie zagwarantować optymalną jakość usług dla różnego rodzaju aplikacji.
EN
The article presents MPLS (Multiprotocol Label Switching), which represents a new level in the development of standards used in combinations of switching technology of the second layer ISO/OSI reference model and routing technology in the third layer. The primary objective of the standardization of MPLS is to create a flexible network structure, which will be much more efficient than existing systems and networks, and will be much more scalable. Having analyzed the results obtained in the simulation tests, we can conclude that the use of MPLS network is able to guarantee optimal quality of service for all kinds of applications.
EN
In the paper we continue our research on traffic modelling in the Next Generation Network (NGN) architecture, which includes the IP Multimedia Subsystem (IMS) elements. A simulation model of a single NGN domain with transport stratum based on the Multiprotocol Label Switching (MPLS) technology is proposed, which allows evaluation of mean response time of this stratum. The simulation model is applied to verify the results obtained using the previously proposed analytical model.
PL
W artykule przedstawiono kontynuację badań dotyczących modelowania ruchu w architekturze Sieci Następnej Generacji (Next Generation Network, NGN) zawierającej elementy koncepcji IP Multimedia Subsystem (IMS). Zaproponowano model symulacyjny dla pojedynczej domeny sieci NGN z warstwą transportową bazującą na technologii Multiprotocol Label Switching (MPLS), który umożliwia wyznaczenie średniego czasu odpowiedzi tej warstwy. Model ten wykorzystano do weryfikacji wcześniej opracowanego modelu analitycznego.
EN
MPLS architecture for transport networks play the significant role in the development of next generation networks, in particular with regard to the guarantee of continuity of communications "end-to-end" through a variety of heterogeneous segments of the telecommunications network. The article presents the concept of Mobile MPLS-TP with the use of OAM channels to support the mobility of users and optimize "Handoff" procedure in a hierarchical network topology.
9
Content available remote Analiza odporności MPLS VPN na narażenia zewnętrzne
PL
Artykuł zawiera analizę i sprawdzenie możliwych reakcji sieci MPLS na ingerencję osób niepowołanych oraz na awarie urządzeń. Do jego realizacji wykorzystano routery firmy Cisco, na których została zbudowana badana sieć szkieletowa, która składała się z pięciu urządzeń. Zostały one połączone w klasyczny model niezawodnościowy w kształcie koperty. Badania polegały na symulowaniu zdarzeń według wcześniej przygotowanych scenariuszy oraz diagnostyce zachowań sieci na poszczególne awarie. W tym celu użyto analizatory i generatory ruchu sieciowego. Dodatkowo badano czasy zbieżności protokołów routingu działających wewnątrz sieci oraz sposobów ich reakcji na wymuszenia zmiany tras.
EN
This article presents analysis and possible reactions of MPLS network on unauthorized access and on device’s failure. Five Cisco routers joined into a core network were used to conduct the project. The devices were connected into a classic reliability model with envelope shape. The key aspects of the research were incidents’ simulation in line with previously prepared scenarios as well as diagnosis of network’s reactions to a particular type of a device failure. These effects were modelled using special devices such as analysers and generators of data traffic. Additionally, the range of the project included measuring convergence time of the routing protocols acting inside the network combined with analysis of reactions to forced changes of route.
10
PL
W pracy przedstawiono i porównano powstałe (lub powstające) w ostatnich latach ważniejsze standaryzacje przeznaczone dla sieci transportowych opartych zarówno na klasycznych rozwiązaniach telekomunikacyjnych, jak i o przełączany Ethernet. Opisano też sposoby transportu danych w sieciach komputerowych. Wskazano na uwarunkowania, które powodują, że rozwiązania typu Ethernet mogą zdominować i zdominują sieci operatorskie. Opisano technologię OTN i wskazano jej podstawowe zalety (w porównaniu z sieciami transportowymi poprzedniej generacji SONET/SDH), w tym redukcję kosztów transportu, efektywne wykorzystanie widma optycznego, elastyczność w architekturze, projektowaniu i wykonaniu sieci, bezpieczeństwo.
EN
This paper presents and compares existing and forthcoming standards for data networks designed with native Ethernet in mind. It will discuss aspects and conclude that Ethernet-type solutions will shape provider networks in the future as they do now. The paper also includes a presentation of OTN technology and compares OTNs with networks of the previous generation, i.e. SONET/SDH, highlighting the advantages of OTN: reduced costs of data transport, efficient exploitation of the optical spectrum, security aspects and the elasticity of architecture in terms of adaptability and scalability.
EN
This paper describes the performance of various methods of QoS assurance for each connection in an environment composed of virtual networks and dedicate end-to-end connections inside them. The authors worked on the basis of research conducted with the use of the authorial network management system named Executed Management, which uses resources virtualization platforms VMware and Mininet for testing purposes. We briefly describe our system and techniques we used and some alternatives we tested and discarded because of their limitations. Functionality and performance of proposed solution to widespread implemented mechanisms as OpenFlow and MPLS are compared. Reasons for selecting well-known techniques to isolate networks and limit bandwidth on different levels of virtualization are considered. The purpose of this paper is to show out our studies and performance we achieved.
EN
Growing expectations for a fast access to information create strong demands for a universal telecommunication network architecture, which provides various services with strictly determined quality. Currently it is assumed that these requirements will be satisfied by Next Generation Network (NGN), which consists of two stratums and includes IP Multimedia Subsystem (IMS) elements. To guarantee Quality of Service (QoS) all NGN stratums have to be correctly designed and dimensioned. For this reason appropriate traffic models must be developed and applied, which should be efficient and simple enough for practical applications. In the paper such a traffic model of a single domain of NGN with transport stratum based on Multiprotocol Label Switching (MPLS) technology is presented. The model allows evaluation of mean transport stratum response time and can be useful for calculating time of processing requests in the entire NGN architecture. Results obtained using the presented model are described and discussed. As a result of the discussion, elementary relationships between network parameters and transport stratum response time are indicated.
13
Content available remote An algorithm of choosing LSPs in the MPLS network with unreliable links
EN
In this paper an algorithm for choosing LSPs in the MPLS network with unreliable links is proposed. The number of lost packets on the failed LSP depends on the restoration time of this LSP on the global backup path. In turn, the restoration time depends on the distance between the node which detected failure and the node responsible for traffic redirection from failed to global backup LSP. To reduce restoration time the distance between these nodes is decreased by length limitation of active LSP. The formulated problem covers limitation of the path length determined by the number of links and limitation of LSP failure probability. The algorithm solving the formulated problem of optimization gives a local solution for given limitations.
PL
W pracy zaproponowano algorytm wyboru ścieżek LSPs w sieciach IP/MPLS o zawodnej strukturze. Liczba utraconych pakietów na uszkodzonej ścieżce LSP zależy od czasu odtwarzania uszkodzonej ścieżki na ścieżce zabezpieczającej. Aby ograniczyć czas odtwarzania, odległość pomiędzy węzłami jest ograniczona poprzez ograniczenie długości ścieżki aktywnej. Rozważany problem obejmuje ograniczenie nałożone na długość ścieżki, mierzonej liczbą łączy oraz ograniczenie prawdopodobieństwa uszkodzenia ścieżki. Algorytm rozwiązujący sformułowany problem optymalizacji przy zadanych ograniczeniach wyznacza rozwiązanie lokalne
EN
Preemption is a traffic engineering technique in Multiprotocol Switching Network that enables creation of high priority paths when there is not enough free bandwidth left on the route. Challenging part of any preemption method is to select the best set of paths for removal. Several heuristic methods are available but no wider comparison had been published before. In this paper, we discusses the dilemmas in implementing preemption methods are presented the simulation studyof well known existing algorithms. Based on the results, we provide recommendations for deployment of preemption for the two most common evaluation criteria: number of preemption and preempted bandwidth.
15
EN
This paper discusses compact node-link formulations for MPLS fast reroute optimal single path layout. We propose mathematical formulations for MPLS fast reroute local protection echanisms. In fact, we compare one-to-one (also called detour) local protection and many-to-one (also called facility backup) local protection mechanisms with respect to minimized maximum link utilization. The optimal results provided by the node-links are compared with the suboptimal results provided by algorithms based on non-compact linear programming (path generation) approach and IP-based approach.
16
EN
The problem that this paper investigates, namely, the working route assignment (WRA) problem, is one that arises naturally from problems of survivable network design that have recently received significant attention in data networking community. We consider an existing MPLS backbone transport network, which is in an operational phase and augmenting its resources is not possible. To address the issue of network survivability we apply restoration, i.e. after a network failure broken connections are dynamically restored. The main goal of our work is twofold. First, we want to develop an effective objective function for optimization of working routes in order to scale network flows and prepare the network for future failures and restoration. Second, we plan to find an efficient method to solve the WRA problem with this new objective function. Therefore, a function called RCL (Residual Capacity and Lost Flow in Link) facilitating the function LFL (Lost Flow in Link) developed previously by the author is formulated. Next, we present an approximation approach, called Lagrangean relaxation with heuristics (LRH) aimed to solve WRA with RCL as objective function. We further draw comparisons between LRH and an existing heuristic based on Flow Deviation algorithm. We also examine the performance of RCL against other functions in the context of network survivability. The results of simulation tests demonstrate that the new algorithm provides sub-optimal results, which are significantly better than other heuristic and the new function RCL can be effectively applied for assignment of working routes in survivable MPLS networks.
17
EN
Our discussion in this article centers around various issues related to the use of anycasting in connection-oriented computer networks. Anycast is defined as a one-to-one-of-many transmission to deliver a packet to one of many hosts. Anycasting can be applied if the same content is replicated over many locations in the network. Examples of network techniques that apply anycasting are Content Delivery Networks (CDNs), Domain Name Service (DNS), Peer-to-Peer (P2P) systems. The role of anycasting is growing concurrently with the popularity of electronic music, movies, and other content required by Internet users. In this work we focus on the optimization of anycast flows in connection-oriented networks. We formulate a model of anycast connections and next propose a heuristic algorithm based on the Lagrangean relaxation aimed to optimize jointly routes for anycast and unicast connections. Results of numerical experiments are presented and evaluated. Finally, we analyze briefly problems related to anycasting in dynamic routing and multi-layer networks.
PL
W referacie dokonano analizy budowy i funkcjonowania oraz metodyki tworzenia wirtualnych sieci prywatnych VPN (Virtual Private Networks). Omówiono zagadnienia związane z realizacją VPN w sieci IP Telekomunikacji Kolejowej oraz przedstawiono warunki realizacji tej usługi i zaproponowane koncepcję sieci TK VPN dla spółki kolejowej.
EN
Paper presents analysis of structure, functioning and methodology of creation of the Virtual Private Networks (VPN). There are described the problems connected with realization of VPN in the IP net of Railway Telecommunication as well as there are presented conditions of realization such a service for Railwayi Companies. The nets VPN allow to assure communication for a lot of users on the base of the common net's infrastructure, in the way which guarantee the logic separation between the groups which are determined in the respective sub-nets.
19
Content available remote On line routing of guaranteed bandwidth with restoration
EN
In this paper the problem of finding a pair of link (node) disjoint active Label Switched Path (LSP) and backup LSP in Multi Protocol Label Switching (MPLS) networks is considered. It was assumed that capacity on the links of the backup Label Switched Paths can be shared. We focus on online algorithms for routing of guaranteed bandwidth of active LSPs and backup LSPs under partial information model in order to optimize the total amount of bandwidth consumed in the MPLS network. We consider only the case of protection against single link (node) failure. In this paper the comparison of two known routing algorithms was carried out. The first of them is based on Integer Linear Programming [3, 4] The second one is based on active-path-first heuristics [8]. In order to avoid the trap-problem the concept of Conflicting Link Set is used. Moreover, new algorithm based on active-path-first heuristics was proposed too. In this paper special attention has been paid to bandwidth consumed in the network, number of rejected connection set-up requests and running time of considered algorithms. The obtained results have proved that the proposed algorithm is comparable to the other algorithms but it has shorter running time then the existing ones.
EN
This paper addresses the problem of non-bifurcated multicommodity flow optimization in survivable networks. As the objective we apply the Lost Flow in Link (LFL) function, which is an upper bound of the flow that can be lost due to a failure of a single link. Since the problem under consideration is NP-complete we propose an exact algorithm to find optimal results. To facilitate the high computation complexity caused by the NP-completeness, we propose three cut inequalities: mixed integer rounding, cover inequality and upper bound on the objective function. Cuts are combined with the branch-and-bound algorithm to construct the branch-an-cut algorithm. We evaluate the proposed cuts by making numerical experiments using five network topologies with various demand patterns. Results of simulation prove the robustness of our approach - combined application of all three cuts reduces the number of nodes and decision time by 80% compared to the branch-and-bound algorithm.
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