Rafal Stankiewicz

Quality of service terminology in IP networks

This article provides an overview of commonly used terminology related to quality of service assurance in IP networks. Several approaches to QoS definition, including those of IETF, ITU, and ETSI, are presented and compared. Terms associated with QoS like class of service, grade of service, service level agreement, as well as service level specification (SLS), traffic conditioning agreement (TCA), and traffic conditioning specification (TCS) are discussed. Terminology used in two QoS architectures, IntServ and DiffServ, is also introduced.

QoX: What is it really?

The article puts in order notions related to Quality of Service that are found in documents on service requirements. Apart from presenting a detailed description of QoS itself, it overviews classes of service (CoS) proposed by main standardization bodies and maps them across various transmission technologies. Standards and concepts related to less commonly used, though not less important, terms such as Grade of Service (GoS), Quality of Resilience (QoR), and Quality of Experience (QoE) are also discussed. While provisioning of QoS, CoS, GoS, and QoR is related to various aspects of networking and network performance, QoE describes resulting service features as perceived by the customer. Relations between those intrinsic network features and resulting human-experienced quality are discussed. The above set of QoX terms (where X stands for Service, Experience, etc.) is sufficient to describe and distinguish all aspects of service provisioning.

A survey of QoE assurance in converged networks

High user satisfaction with using an application or service is the most meaningful quality evaluation criterion. For this reason the set of issues encompassed by the term quality of experience (QoE), i.e., the quality perceived subjectively by the end-user, is key to Internet service providers, network and software engineers, developers and scientists. From the technical point of view, to assure a high level of QoE, an appropriate level of quality of service (QoS), grade of service (GoS), and quality of resilience (QoR) must be provisioned by the network involved in service delivery. This paper studies QoE provisioning approaches with respect to the following convergence requirements: any service, anywhere, anytime, any user device, any media and networking technology, and by any operator. Challenges related to QoS, GoS and QoR provisioning in converged networks and implications on QoE provisioning are discussed. Convergence between fixed and wireless networks as well as within wireless networks based on different technologies, are considered. A variety of technologies and concepts for future converged networks are discussed.

Interaction patterns between P2P content distribution systems and ISPs

Peer-to-peer (P2P) content distribution systems are a major source of traffic in the Internet, but the application layer protocols they use are mostly unaware of the underlying network in accordance with the layered structure of the Internets protocol stack. Nevertheless, the need for improved network efficiency and the business interests of Internet service providers (ISPs) are both strong drivers toward a cross-layer approach in peer-to-peer protocol design, calling for P2P systems that would in some way interact with the ISPs. Recent research shows that the interaction, which can rely on information provided by both parties, can be mutually beneficial. In this article we first give an overview of the kinds of information that could potentially be exchanged between the P2P systems and the ISPs, and discuss their usefulness and the ease of obtaining and exchanging them. We also present a classification of the possible approaches for interaction based on the level of involvement of the ISPs and the P2P systems, and we discuss the potential strengths and the weaknesses of these approaches.

A survey on methods to provide multipath transmission in wired packet networks

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, Valiants 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.

Analytical Models for Multi-RED Queues Serving as Droppers in DiffServ Networks

The paper proposes analytical models of two types of multi-RED queues, WRED and RIO-C, serving as droppers in DiffServ networks. Both are scrutinized under two types of configuration of threshold parameters: staggered and overlapped. The proposed analysis uses the M(n)/M/1/K and M(n)/D/1/K queuing models (queuing systems with balking). Additionally, in the case of RIO-C, a Bernoulli scheme is adopted in the model. The models are validated under two types of traffic: ftp-like and web-like. Recommendations on the selection of the most appropriate model are provided.

Modeling of TCP behavior in a DiffServ network supporting assured forwarding PHB

The paper presents a mathematical model of the TCP behavior in a DiffServ network and its empirical validation. The assured forwarding per hop behavior is modeled. The model is modular - individual components of DiffServ nodes are described by separate sets of equations. It makes it easy to develop a model of a system consisting of various types of DiffServ node elements (meters/markers, shaper/droppers) just by changing some of the equations. The input traffic is divided into several traffic aggregates each having a part of a bottleneck capacity dedicated to it.

Cost-Driven Peer Rating Algorithm

The paper presents a concept of a rating algorithm aiming at overall peer-to-peer traffic reduction (and locality awareness) and decrease of load on costly links, thus diminishing operators costs. The rating algorithm is not only performed by a sole Oracle, as is typically proposed, but its operation is also supported by a similar entity located in other domains. Due to this concept, a usually omitted fact that the inter-domain routes are asymmetrical is properly dealt with. Simulations performed on a real topology show the usefulness of the presented approach.

Enterprise-oriented cybersecurity management

Information technology is widely used in processes vital to enterprises. Therefore, IT systems must meet at least the same level of security as required from the business processes supported by these systems. In this paper, we present a view on cybersecurity management as an enterprise-centered process, and we advocate the use of enterprise architecture in security management. Activities such as risk assessment, selection of security controls, as well as their deployment and monitoring should be carried out as a part of enterprise architecture activity. A set of useful frameworks and tools is presented and discussed.

Analytical models for DiffServ meter/markers

The paper presents mathematical models for meter/markers serving as DiffServ node elements. Models for two types of token bucket based meter/markers: single rate three color marker and two rate three color marker and a model for a rate estimator based meter/marker, i.e. time sliding window three color marker, are provided. Experimental validation of these models is also presented.