Robert Wojcik - Academia.edu (original) (raw)

Papers by Robert Wojcik

Computer Communications, 2019

Flow-Aware Multi-Topology Adaptive Routing (FAMTAR) is a new approach to multipath and adaptive r... more Flow-Aware Multi-Topology Adaptive Routing (FAMTAR) is a new approach to multipath and adaptive routing in IP networks which enables automatic use of alternative paths when the primary one becomes congested. It provides more efficient network resource utilization and higher quality of transmission compared to standard IP routing. However, thus far it has only been evaluated through simulations. In this paper we share our experiences from building a real-time FAMTAR router and present results of its tests in a physical network. The results are in line with those obtained previously through simulations and they open the way to implementation of a production grade FAMTAR router.

International Journal of Communication Systems, 2017

We demonstrate a new approach to assuring fairness in flow-aware networking. Standard routine in ... more We demonstrate a new approach to assuring fairness in flow-aware networking. Standard routine in flow-aware networking guarantees that each flow receives the same amount of resources. This property can be exploited by dividing a single transmission into a number of flows. We propose and evaluate the per-user fair packet scheduling mechanism, which ensures fairness among users (not flows). We also compare the new mechanism with the one already known from the literature, which is based on altering the admission control routine. Evaluation shows that the new concept of fairness provides better performance and fair resource distribution regardless of the behavior of users.

Journal of Network and Systems Management, 2016

As global internet traffic continues to increase, network operators face challenges on how to eff... more As global internet traffic continues to increase, network operators face challenges on how to efficiently manage transmission in their networks. Even though attempts are underway to make optical networks automatic, the majority of actions related to traffic engineering are still performed manually by the administrators. In this paper we propose an Automatic Hidden Bypasses approach to enhance resource utilization in optical networks. Our solution uses the softwaredefined networking concept to automatically create or remove hidden bypasses which are not visible at the network layer. The mechanism increases throughput and reduces transmission delays.

2013 International Conference on Computing, Networking and Communications (ICNC), 2013

Fair rate degradation and its negative impact on the performance of transmissions in Flow-Aware N... more Fair rate degradation and its negative impact on the performance of transmissions in Flow-Aware Networks is a documented problem. In addition, a simple solution to the problem is known. In this paper, it is shown that the measurement-based admission control block can be enhanced so that the problem of fair rate degradation becomes negligible. The proposed solution allows better tuning of the mechanism and, therefore, provides better quality assurance. It is shown that the amount of time in which the fair rate drops below a certain threshold can be drastically minimized compared to the standard static approach.

Lecture Notes in Computer Science, 2009

This paper presents the impact of congestion control mechanisms proposed for Flow-Aware Networks ... more This paper presents the impact of congestion control mechanisms proposed for Flow-Aware Networks on packet transmission in the overloaded network after a link failure. The results of simulation based analysis show how to set the values of the congestion control parameters in order to decrease the acceptance time of the interrupted streaming flows in the backup link. The research was performed for three congestion control mechanisms, the Enhanced Flushing Mechanism (EFM), the Remove Active Elastic Flows (RAEF), and Remove and Block Active Elastic Flows (RBAEF) in two different cross-protect router architectures, with the PFQ (Priority Fair Queuing) and with the PDRR (Priority Deficit Round Robin) scheduling algorithms. Moreover, the advantages and weaknesses of using the proposed solutions in FAN, considering the effects of a network element failure, are described and analyzed.

2010 IEEE International Conference on Communications, 2010

In this paper, it is shown that the admission control routine in Flow-Aware Networks (FAN) may le... more In this paper, it is shown that the admission control routine in Flow-Aware Networks (FAN) may lead to severe fair rate degradation, which negatively impacts the performance of streaming applications. In order to prevent this negative behavior, the limitation mechanism is proposed. The aim of the mechanism is to limit the maximum number of new flows that may be admitted on a link between any two consecutive network's automeasurements. The solution is efficient, viable and dramatically reduces the fair rate degradation.

2012 IEEE International Conference on Communications (ICC), 2012

A new fairness concept for Flow-Aware Networks (FAN) is presented and analyzed in the paper. In c... more A new fairness concept for Flow-Aware Networks (FAN) is presented and analyzed in the paper. In contrast to basic FAN, where elastic flows are treated similarly, it assumes fair access to the resources for each user independently of how many flows it generates. A new method for estimating the values of the fair rate, which is the key congestion control parameter in FAN is also provided. The new solution allows for reducing the oscillations of the periodically measured values which influences more stable transmission in the network. The new method allows for describing the traffic in a more realistic way, simultaneously simplifying its implementation in the FAN routers. Finally, the results of the simulation analysis of FAN with the new fairness algorithm and the Remove and Accept Most Active Flows (RAMAF) congestion control mechanism are presented for two versions of the TCP protocol: NewReno and NewJersey.

GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference, 2009

A complete system which ensures reliable transmission of streaming flows in Flow-Aware Networks (... more A complete system which ensures reliable transmission of streaming flows in Flow-Aware Networks (FAN) is presented and analyzed in the paper. A new congestion control mechanism, called RPAEF (Remove and Prioritize in access Active Elastic Flows), is described in details. It allows for fast acceptance of new streaming flows in the admission control (AC) block of FAN routers. The mechanism of limiting the number of new flows accepted in the AC block is provided as an answer to the scalability problem of all congestion control mechanisms proposed for FAN up to now. The global list of protected flows ensures that all streaming flows redirected from the primary route in case of a network element failure are immediately accepted in the first router on a backup route. The advantages and weaknesses of the proposed solutions are described and analyzed. Moreover, it is shown that the simultaneous implementation of all of them ensures fast, scalable and reliable transmission of streaming flows in FAN.

IEEE Communications Letters, 2014

Internet routing processes currently rely on protocols that were developed more than ten years ag... more Internet routing processes currently rely on protocols that were developed more than ten years ago. Today, we have far more computational power and memory at our disposal, and it is possible to take advantage of these resources in order to greatly increase the efficiency of routing protocols. Therefore, we propose a new approach to routing packets in IP-based networks: Flow-Aware Multi-Topology Adaptive Routing, or FAMTAR. FAMTAR combines flow-aware traffic management and an adaptive routing mechanism. A standard routing protocol is used to find the optimal path between two nodes in a network. FAMTAR makes it possible to automatically create additional paths when such demand occurs. Between two endpoints, the transmission may follow n different paths, where n is limited only by the topology of the network. In this letter, we compare FAMTAR to a classic routing protocol and demonstrate FAMTAR's superiority.

2009 11th International Conference on Transparent Optical Networks, 2009

In this paper, the admission control policies proposed for Cross-Protect routers in Flow-Aware Ne... more In this paper, the admission control policies proposed for Cross-Protect routers in Flow-Aware Networks (FAN) are compared. A Multilayer FAN (MFAN) architecture defines policies to decide which flows are more suitable to be transmitted through the optical layer in case of congestion. In this work, we evaluate how to include the information of such policies in the admission control process. As a result of the analysis, a new admission control strategy is proposed. This solution inherits the advantages from already established admission control proposals while ensuring fast acceptance times of new streaming flows.

Computer Networks, 2015

IP networks were designed to provide general connectivity. At their advent, routing methods focus... more IP networks were designed to provide general connectivity. At their advent, routing methods focused only on finding one optimal path between given endpoints. Although many solutions to sending traffic via multiple paths have appeared over time, the majority of current IP networks are still managed to support only single-path transmissions. This survey examines various approaches which can provide multipath transmissions in existing IP networks. Firstly, the most recognizable solutions are presented, and later, less well-known proposals are introduced. We show how it is possible to realize multipath transmission in source and hop-by-hop routing, multi-topology routing, bio-inspired routing solutions, Valiant's routing, Multi-Protocol Label Switching, Software-Defined Networks, Flow-Aware Multi-Topology Adaptive Routing, Shortest-Path Bridging, Transparent Interconnection of Lots of Links, network virtualization, and Multipath TCP. Moreover, the mentioned approaches are compared, contrasted and subjectively assessed. The goal of the survey is to show that multipath transmissions can be achieved in the current IP networks and in many different ways.

2014 16th International Telecommunications Network Strategy and Planning Symposium (Networks), 2014

Measurement-based admission control mechanism in Flow-Aware Networks (FAN) may lead to performanc... more Measurement-based admission control mechanism in Flow-Aware Networks (FAN) may lead to performance issues related to over-admitting, especially when traffic sources generate large number of flows. When too many new transmissions arrive close in time to each other, all of them may be accepted even though there is no room in the outgoing link. The source lies, unfortunately, in the very basic principles of the mechanism. In this paper, we show that there is a simple, yet very efficient remedy to the problem. The proposed solution utilizes the Random Early Detection algorithm. As a result we can steer the number of accepted flows taking into consideration current load in a link. The proposed solution has significant advantages over currently available algorithms for admission control in FAN. Moreover it provides better performance which is confirmed by the simulation results.

IEEE Communications Magazine, 2014

Lecture Notes in Computer Science, 2011

Overlay applications generate huge amounts of traffic in the Internet, which determines a problem... more Overlay applications generate huge amounts of traffic in the Internet, which determines a problem for Internet Service Providers, since it results in high charges for inter-domain traffic. Traditional traffic management techniques cannot deal successfully with overlay traffic. An incentive-based approach that employs economic concepts and mechanisms is required in order to deal with the overlay traffic in a way that is mutually beneficial for all stakeholders of the Future Internet. This "TripleWin" situation is the target of Economic Traffic Management (ETM). A wide variety of techniques are employed by ETM for optimizing overlay traffic management considering performance requirements of overlay and underlay networks together with cost implications for ISPs. However, the assessment of ETM requires an innovative methodology. In this article this methodology is described and major results are presented as obtained accordingly from the evaluation of different ETM mechanisms.

2009 7th International Workshop on Design of Reliable Communication Networks, 2009

Network operators are migrating towards IP over WDM architectures. In such multi-layer networks, ... more Network operators are migrating towards IP over WDM architectures. In such multi-layer networks, it is necessary to efficiently use the resources available from both layers in order to provide coordinated recovery strategies. Thanks to the development of the control plane (GMPLS and ASON), it is feasible to set up and tear down lightpaths automatically, so the WDM layer itself can support failure recovery. This paper describes a multi-layer recovery strategy in a FAN/WDM (Flow-Aware Networking/Wavelength Division Multiplexing) architecture. We propose using the EHOT (Enhanced Hold-Off Timer) algorithm to control network operation after link or node failure. Although FAN operates only on the IP level, the presented analysis shows that it is possible to ensure sufficiently low (less than 50 ms) recovery times in FAN working over an intelligent optical layer. Additionally, the paper shows the motivation for FAN networks and presents the results of carefully selected simulation experiments which allow for evaluating the duration of outages in data transmission under various conditions.

Computer Networks, 2010

Any queries or remarks that have arisen during the processing of your manuscript are listed below... more Any queries or remarks that have arisen during the processing of your manuscript are listed below and highlighted by flags in the proof. Please check your proof carefully and mark all corrections at the appropriate place in the proof (e.g., by using on-screen annotation in the PDF file) or compile them in a separate list.

Transactions on Emerging Telecommunications Technologies, 2014

A resilience analysis of protection cycles (p-cycle) configurations for Double Rings with Dual At... more A resilience analysis of protection cycles (p-cycle) configurations for Double Rings with Dual Attachment (DRDAs) architectures is presented in this work. DRDAs are composed of two rings with corresponding nodes connected by two separated links. There are several possible configurations of p-cycles, which may be used in DRDAs for improving link or node protection upon link failure. The values of the parameters Mean Time To Failure and Mean Time To Disconnection are analysed in the paper to show the best choice of p-cycles in DRDAs architectures.

2017 International Conference on Computing, Networking and Communications (ICNC), 2017

IEEE Communications Letters, 2016