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.
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W ostatnich latach jesteśmy świadkami szybkiego rozwoju sieci komputerowych. W wielu dziedzinach życia sieci komputerowe używane są jako podstawowy środek służący do przesyłania wielu rodzajów informacji. Awaria elementu sieci komputerowej może mieć duże znaczenie, gdyż nawet krótkotrwała przerwa w transmisji powoduje utratę wielu informacji. Konsekwencją awarii mogą być: straty finansowe, konflikty polityczne, ludzkie zdrowie. Stąd wzrost znaczenia kryteriów niezawodnościowych służących do projektowania przeżywalnych (ang. survivable) i samonaprawialnych (ang. selfhealing) sieci komputerowych. W tej pracy poruszono zagadnienia związane z niezawodnością sieci komputerowych zorientowanych połączeniowo, gdyż w większości sieci szkieletowych używane są techniki połączeniowe. Skoncentrowano się na dwóch popularnych technikach: ATM (ang. Asynchronous Transfer Mode) oraz MPLS (ang. Multiprotocol Label Switching). Przedstawiono oraz porównano najważniejsze metody służące do zapewniania niezawodności. Dodatkowo przeanalizowano różne sposoby oraz algorytmy służące do projektowania niezawodnych sieci komputerowych.
EN
Currently we are witnesses of tremendous development of computer networks. Many organizations, institutions, companies use computer networks as a primary medium for transmitting of many kind of information. Service disruptions in modern networks, are expected to be important, since loss of services and traffic in high-speed fiber systems could cause a lot of damages including economic loses, significant revenue loss, political conflicts, human health. Hence engineers and network companies work on self-healing restoration methods to provide network reliability and survivability. In this paper problems of network reliability and survivability in connection oriented networks are addressed, since most of backbone network technologies are connection oriented. Two techniques: ATM and MPLS are presented, discussed and compared with special focus on main methods proposed to provide reliability and survivability. Furthermore the most important techniques and algorithms applied in the process of reliable network design are analyzed.
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The main objective of this paper is to develop an effective evolutionary algorithm (EA) for the path-assignment problem in survivable connection-oriented networks. We assume a single-link failure scenario, which is the most common and frequently reported failure event. Since the network flow is modeled as a non-bifurcated multicommodity flow, the discussed optimization problem is NP-complete. Thus, we develop an effective heuristic algorithm based on an evolutionary algorithm. The main novelty of this work is that the proposed evolutionary algorithm consists of two levels. The “high” level applies typical EA operators. The “low” level is based on the idea of a hierarchical algorithm. However, the presented approach is not a classical hierarchical algorithm. Therefore, we call the algorithm quasi-hierarchical. We present its description and the results of simulation runs over various networks.
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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.
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