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DOI: 10.1023/A:1017462927359
Print publication date: 3/1/2002
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by Pras, Aiko; Festor, Olivier

DOI: 10.1023/A:1014510910520
Print publication date: 3/1/2002
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by Ozmutlu, H. Cenk; Gautam, Natarajan; Barton, Russell

To predict the delay between a source and a destination as well as to identify anomalies in a network, it is useful to continuously monitor the network by sending probes between all sources and destinations. Some of the problems of such probing strategies are: (1) there is a very large amount of information to analyze in real time; and (2) the probes themselves could add to the congestion. Therefore it is of prime importance to reduce the number of probes drastically and yet be able to reasonably predict delays and identify anomalies. In this paper we formulate a graph-theoretic problem called the Constrained Coverage Problem to optimally select a subset to traceroute-type probes to monitor networks where the topology is known. To solve this problem, we develop a heuristic algorithm called the Constrained Coverage Heuristic (CCH) algorithm, which works in polynomial time, as an alternative to the standard exponential-time integer programming solution available in commercial software. The application of the Constrained Coverage Problem to randomly generated topologies yielded an 88.1% reduction in the number of monitored traceroute-type probes on average. In other words, networks can be successfully monitored using only 11.9% of all possible probes. For these examples, the polynomial time CCH algorithm performed remarkably well in comparison to the standard exponential time integer programming algorithm and obtained the optimal (in 24 of 30 examples) or near optimal (second best solution in the remaining examples) solutions in a comparatively negligible amount of time.

DOI: 10.1023/A:1014457726450
Print publication date: 3/1/2002
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by Boutaba, Raouf; Polyrakis, Andreas

During the past years, IP networks have grown considerably in size and complexity: the number and the variety of the connected devices have increased, new applications have emerged and Quality-of-Service is increasingly demanded. In such networks, traditional management techniques seem to suffer from significant scalability and efficiency limitations. Policy-Based Networking (PBN) has emerged as a promising paradigm for IP networks operation and management. In PBN, policy servers enforce network policies by sending the appropriate configuration data to the managed devices. IETF is currently developing COPS (Common Open Policy Service) and its extension for policy provisioning, COPS-PR, as the protocols to implement PBN. COPS-PR, although initially biased towards DiffServ, has received significant attention and seems efficient for several other management areas, such as accounting and IP filtering. However, in COPS-PR, the rigidity of the policy-enforcing mechanisms at the managed devices restricts the intelligence that can be pushed into them. This work attempts to raise these limitations by extending the COPS-PR protocol with meta-policies. Meta-policies are rules that can be stored and processed by the devices, independent of their semantics. They allow intelligence to be pushed towards the managed device, making in this way the scheme more efficient, scalable, distributed and robust.

DOI: 10.1023/A:1014405609612
Print publication date: 3/1/2002
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by Papaioannou, Thanasis G.; Sartzetakis, Stelios; Stamoulis, George D.

The demand for QoS provisioning support over Internet grows continuously. One of the factors contributing to this demand is the increasing penetration of Application Service Providers (ASPs) to the market. This necessitates the development of mechanisms for the efficient realization of Service Level Agreements (SLA). In this paper, we develop and evaluate an approach for efficient SLA selection and implementation (support, policing/shaping, and charging) in a DiffServ-over-MPLS network domain. We describe how this approach is applied in a realistic service provision scenario based on the ASP service model. A negotiation process between a user and a network provider is introduced; thus the user can choose from the alternative options for allocation of resources the one that better matches his needs. For the purposes of negotiation, we develop an appropriate utility model that expresses user preferences in a simple yet informative way. Furthermore, we discuss the implementation of our approach in a small-scale experimental DiffServ-over-MPLS network, for the case of a simple scenario of ASP services provision. We also assess the economic efficiency of our approach by means of simulation experiments, the results of which advocate that our approach is incentive compatible, in the sense that individual optimization by each user (in SLA selection) also leads to improved social welfare. Our approach is quite general and can be combined with several policies for network management, or as a complement to the traffic engineering procedures.

DOI: 10.1023/A:1014453525541
Print publication date: 3/1/2002
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by Bauer, Michael A.; Akhand, Hadee A.

Advances in networks during the past decades have fostered the deployment of a variety of Internet applications. Many of these applications have a range of Quality-of-Service (QoS) requirements, some involving network throughput, delay, and reliability. Consequently, there is growing need for network services that can differentiate applications having QoS requirements from those without and to be able to further classify applications with QoS requirements into different classes at the IP-network level. The Internet Engineering Task Force (IETF) has proposed Differentiated Services (DiffServ) to provide QoS in IP-based networks. The goal of DiffServ is to define configurable types of packet forwarding that can provide service differentiation for large aggregates of network traffic. We report on our investigation of Relative Proportional Differentiated Services to implement DiffServ in IP-based networks and one that supports the provisioning and management of QoS for Internet Applications. The main contributions of the paper are the introduction of a novel traffic conditioning architecture for the marker and shaper/policer which relies on feedback from a metering component, and the provision for a QoS manager to enable a network administrator or a management application to dynamically adjust control parameters.

DOI: 10.1023/A:1014401508703
Print publication date: 3/1/2002
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by Khalil, Ibrahim; Braun, Torsten

Customers of Virtual Private Networks (VPNs) over Differentiated Services (DiffServ) infrastructure are most likely to demand not only security but also guaranteed Quality-of-Service (QoS) in pursuance of their desire to have leased-line-like services. However, expectedly they will be unable or unwilling to predict the load between VPN endpoints. This paper proposes that customers specify their requirements as a range of quantitative services in the Service Level Agreements (SLAs). To support such services Internet Service Providers (ISPs) would need an automated provisioning system that can logically partition the capacity at the edges to various classes (or groups) of VPN connections and manage them efficiently to allow resource sharing among the groups in a dynamic and fair manner. While with edge provisioning a certain amount of resources based on SLAs (traffic contract at edge) are allocated to VPN connections, we also need to provision the interior nodes of a transit network to meet the assurances offered at the boundaries of the network. We, therefore, propose a two-layered model to provision such VPN-DiffServ networks where the top layer is responsible for edge provisioning, and drives the lower layer in charge of interior resource provisioning with the help of a Bandwidth Broker (BB). Various algorithms with examples and analyses are presented to provision and allocate resources dynamically at the edges for VPN connections. We have developed a prototype BB performing the required provisioning and connection admission.

DOI: 10.1023/A:1014449424633
Print publication date: 3/1/2002
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by Lin, Geng; Shen, Chien-Chung

DOI: 10.1023/A:1014497307794
Print publication date: 3/1/2002
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by Fonseca, Nelson L. S. da; Oliveira, Rodrigo M.

DOI: 10.1023/A:1014446723724
Print publication date: 3/1/2002
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