Lexicographically optimal balanced networks

We consider the problem of allocating bandwidth between two endpoints of a backbone network so that no parts of the network are unnecessarily loaded. We formulate the problem as lexicographic optimization and develop algorithms for its solution. The solution consists of: (1) identifying a cut in the network where the optimal load can be determined on all the links of the cut and (2) considering the same problem for each of the subnetworks to which the cut is dividing the original network.     

The AGAVE approach for network virtualization: differentiated services delivery

This paper describes a new paradigm to realize network virtualization and defines two novel concepts, network planes and parallel Internets, to achieve service differentiation. These concepts are packaged in a technology-agnostic and a multi-dimensional approach for the delivery of Internet protocol (IP) service differentiation, both intra- and inter-domain. The definition of the aforementioned concepts covers several dimensions, mainly routing, forwarding, and traffic management ones. Unlike some radical “Post IP” proposals, this paper advocates an evolutionary approach for enhancing the level of experienced connectivity services (including quality of service and robustness) and therefore to enhance the Internet of the future. Both the rationale and the merits of our approach are explained. In addition, this paper focuses on the critical problem of determining the network planes and parallel Internets to be engineered by a given IP network provider to meet the service connectivity requirements of external service providers. Finally, in order to assess the validity of the proposed approach, a network plane Emulation Platform is described.     

Service-driven traffic engineering for intradomain quality of service management

Quality of service delivery in IP networks is an important area for service providers, pointing to new business opportunities for premium quality traffic. While there has been relevant research on traffic engineering for QoS management, the problem has never been addressed through a holistic approach that brings together service management and traffic engineering. We present an integrated approach to intradomain QoS management that brings together two-level service management and traffic engineering approaches, coupled through the concept of the resource provisioning cycle. We present validation results for MPLS-based traffic engineering through both testbed experimentation and simulation; we also present validation results for monitoring through testbed experimentation. The article updates, enhances, and validates the top-level view of this integrated architecture presented in our earlier paper (see Trimintzios, P. et al., IEEE Commun. Mag., vol.39 no.5, 2001).     

Provisioning for interdomain quality of service: the MESCAL approach

This article presents an architecture for supporting interdomain QoS across the multi-provider global Internet. While most research to date has focused on supporting QoS within a single administrative domain, mature solutions are not yet available for the provision of QoS across multiple domains administered by different organizations. The architecture described in this article encompasses the full set of functions required in the management (service and resource), control and data planes for the provision of end-to-end QoS-based IP connectivity services. We use the concept of QoS classes and show how these can be cascaded using service level specifications (SLSs) agreed between BGP peer domains to construct a defined end-to-end QoS. We illustrate the architecture by describing a typical operational scenario.     

Interdomain routing through QoS-class planes [Quality-of-Service-Based Routing Algorithms for Heterogeneous Networks]

This article presents an approach to delivering qualitative end-to-end quality of service (QoS) guarantees across the multiprovider Internet. We propose that bilateral agreements between a number of autonomous systems (ASs) result in the establishment of QoS-class planes that potentially extend across the global Internet. The deployment of a QoS-enhanced border gateway protocol (BGP) with different QoS-based route selection policies in each of the planes allows a range of interdomain QoS capabilities to coexist on the same network infrastructure. The article presents simulation results showing the benefits of the approach and discusses aspects of the performance of QoS-enhanced BGP     

Experiments and enhancements for IP and ATM integration: the IthACIproject

IthACI has been a European project in the ACTS framework concentrating on fast layer 2 forwarding methods for IP traffic based on labeled flow mechanisms. The approach is also known as IP switching and is considered promising for enhancing IP performance. Several flavors of IP switching have been proposed by various vendors (e.g., IP switching by Ipsilon, Tag Switching by Cisco, ARIS by IBM, IPSOFACTO by the NEC), all of them different and not interoperable. IP switching has been adopted by the IETF under the umbrella of multiprotocol label switching (MPLS). Although MPLS has made remarkable progress, a number of issues remain largely open for further investigation. The scope of the IthACI project was to address such issues and propose solutions. The issues addressed were multicast, QoS, resource management, and mobility support in a multicast environment. IthACI conducted both theoretical and experimental work. Three network islands, each based on a different flavor of IP switching, were set-up and the interoperability of these different IP switching/MPLS flavors were investigated and demonstrated     

Barley beta-glucosidase: expression during seed germination and maturation and partial amino acid sequences

Confusion regarding proper use of the terms rate and risk persists in the literature. This has implications for the proper modeling of prognosis and transition between health states in decision analysis and related techniques. The issue is complicated by the plethora of terms related to rate and risk. Although the suggestion to use the terms force and probability as substitutes for rate and risk has some appeal, the change in terminology by itself is unlikely to solve all the confusion or misuse of terms. This paper clarifies the proper definitions and estimations of rates and risks and suggests critical factors for the decision analyst to remember when using, modeling, or interpreting transition rates and risks.     

Technology interoperation in ATM networks: the REFORM system

This article addresses the applicability and interoperation of standards and emerging technologies for the operation and management of ATM networks. The issue is tackled from a practical perspective based on experiences gained through the design, realization, and experimentation of a system developed by the ACTS AC208 REFORM project. Assuming an ATM-based network infrastructure offering a range of services with distinct QoS guarantees, the REFORM system encompasses the required functions for ensuring cost-effective network survivability and availability; fast-responding reliable fault detection and self-healing mechanisms, distributed dynamic routing functions with inherent load balancing capabilities, efficient VP layer design, and dynamic network reconfiguration functions. A number of standards and emerging technologies were used for designing and realizing the wide spectrum of functionality incorporated within the REFORM system, including ITU-T OAM 1.610 and Q.2931, ATM Forum UNI 3.0 and PNNI v. 1, OMG CORBA and Component Model, TINA NRA and ISO/OSI, and ITU-T TMN. Based on the experience gained, the article discusses and draws conclusions on the applicability, coexistence, and interoperation of the adopted technologies. It is shown that these technologies can coexist, through careful design, to the benefit of network design and operation     

A management and control architecture for providing IPdifferentiated services in MPLS-based networks

As the Internet evolves toward the global multiservice network of the future, a key consideration is support for services with guaranteed quality of service. The proposed differentiated services framework is seen as the key technology to achieve this. DiffServ currently concentrates on control/data plane mechanisms to support QoS, but also recognizes the need for management plane aspects through the bandwidth broker. In this article we propose a model and architectural framework for supporting DiffServ-based end-to-end QoS in the Internet, assuming underlying MPLS-based explicit routed paths. The proposed integrated management and control architecture will allow providers to offer both quantitative and qualitative services while optimizing the use of underlying network resources