A new proposal for assuring services in internet

In this paper we present a new mechanism to provide an assured service in terms of target rate and fair excess bandwidth, like the Internet Assured Service. Research in Internet Assured Service faced up both questions in separate ways proposing different traffic conditioners to work with the RIO buffer management, and proposing different modifications to this buffer management, among others. In this work, we suggest using a buffer management scheme different from RIO that also treats in-of-profile and out-of-profile packets differently but avoiding interference between them. This scheme is used together with the Counters Based traffic conditioner because of its high accuracy in guaranteeing target rates. We evaluate and compare by simulation the performance of our proposal using TCP RENO sources. One important issue to be considered is that the proposal is a feasible alternative to the standard architecture for Differentiated Services in Internet.This work was supported by the Spanish Research Council under grant TIC2000-1734- C03-03

Cell Multiplexing and Adaptive Scheduling for Wide Area ATM Networks

The ATM UBR, GFR over ABR service categories have been designed for data. However several studies have responded poor TCP performance over satellite ATM resources. We first discuss the various design options available for TCP end systems, IP-ATM switches for long latency connections. We discuss the buffer management policies generated and rate services and the virtual stores destination options in ATM. We present comparison of ATM service categories for TCP transport over satellite links. Keywords: Video Teleconferencing, Adaptive Schedulin

Proportional bandwidth distribution in IP networks implementing the assured forwarding PHB

Recent demands for new applications are giving rise to an increasing need of Quality of Service (QoS). Nowadays, most IP-based networks tend to use the DiffServ architecture to provide end-to-end QoS. Traffic conditioners are a key element in the deployment of DiffServ. In this paper, we introduce a new approach for traffic conditioning based on feedback signaling among boundary nodes and traffic conditioners. This new approach is intended to provide a poportional distribution of excess bandwidth to endusers. We evaluate through extensive simulations the performance of our proposal in terms of final throughput, considering contracted target rates and distribution of spare bandwidth. Results show a high level of fairness in the excess bandwidth allocation among TCP sources under different network conditions

Counters-based modified traffic conditioner

Traffic conditioners play a key role in implementing the Assured Service in the framework of the DiffServ approach. Many research papers have focused on finding the best traffic conditioner able to assure contracted target rates and to fairly distribute the excess bandwidth among competing sources. Nevertheless, none of the proposals presented so far accomplishes simultaneously both features. We propose a traffic conditioner for the Internet Assured Service called Counters-Based Modified (CBM) that strictly guarantees target rates and performs a fair share of the excess bandwidth among TCP Reno sources. The ability of strictly providing the inbound bandwidth is inherited from its predecessor the Counters-Based algorithm, and the fairness in the outbound bandwidth distribution is met by probabilistically dropping OUT packets in the traffic conditioner. To determine the dropping probability of an OUT packet, the amount of excess bandwidth and the average RTT of all connections in the traffic conditioner have to be known. Although this fact implies using some sort of signaling, it results more feasible than other proposed intelligent traffic conditioners. The CBM traffic conditioner is evaluated under different conditions by simulation using TCP Reno sources. Simulation results presented in this paper lead us to suggest it as a feasible election for the traffic conditioner device implementation in DiffServ.This work was supported by the Spanish Research Council under grant FAR-IP TIC2000-1734-C03-03

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

SZEROKOPASMOWE SATELITARNE SIECI DANYCH W KONTEKŚCIE DOSTĘPNYCH PROTOKOŁÓW I PLATFORM CYFROWYCH

Satellites are the transmission medium for providing connectivity and building global, continental, or regional networks around the world (satellite operators effectively use satellites to support Internet traffic), and point-to-point connections are also possible. In practical use, there are combinations of VSAT networks with terrestrial wireless extensions, allowing end users to increase the capabilities offered via satellite. This paper provides selected information on broadband satellite networks using VSAT technology, including available protocols and transmission platforms. The aim of the article is also to present the chosen technical aspects of satellite networks working with the usage of VSAT technology.Satelity stanowią medium transmisyjne dla zapewnienia łączności i budowy sieci globalnych, kontynentalnych czy regionalnych na całym świecie (operatorzy satelitarni efektywnie wykorzystują satelity do obsługi ruchu internetowego), przy czym możliwe są także połączenia typu punkt-punkt. W praktycznym użyciu są kombinacje sieci VSAT z bezprzewodowymi rozszerzeniami naziemnymi, co pozwala zwiększyć użytkownikom końcowym możliwości oferowane za pośrednictwem satelity. W artykule zamieszczono wybrane informacje na temat szerokopasmowych sieci satelitarnych z wykorzystaniem technologii VSAT, z uwzględnieniem dostępnych protokołów i platform transmisyjnych. Celem artykułu jest także przedstawienie wybranych aspektów technicznych sieci satelitarnych pracujących z wykorzystaniem technologii VSAT

How (Un)Fair are the ABR Binary Schemes, Actually?

It is well known that a simple binary feedback rate--based congestion avoidance scheme cannot ensure a fairness goal of the Available Bit Rate (ABR) service, namely, max--min fairness. In this paper we show how the rates are distributed for the network consisting of the binary switches, and end--systems employing an additive--increase/multiplicative decrease rate control. The modeling assumptions fairly resembles the ABR congestion avoidance, and applies to an arbitrary network topology. The results are obtained on the basis of a stochastic modeling, upon which we obtain certain analytical results, and conduct a numerical simulation. We validate the stochastic modeling through a discrete--event simulation. We believe that modeling presented in this paper enlight the performance issues of the binary ABR schemes. Keywords ABR, ATM, congestion control, binary scheme, EFCI, fairness, max--min, proportional fairness, stochastic approximation, ODE, Lyapunov, Runge-Kutta

Análisis de las prestaciones del acondicionador de tráfico CBM en un dominio DiffServ

The Counters-Based Modified (CBM) traffic conditioner was introduced in a previous work as a feasible option to implement the Assured Forwarding (AF) service in DiffServ. In this paper we present an end-to-end performance analysis of TCP Reno sources that employ the CBM in a DiffServ domain. We present simulation results in a three-RIO-node topology under miscellaneous characteristics: different contract rates, heterogeneous RTT, co-existance of best-effort and AF sources, and eficience of CBM when some network node does not implement service differentiation. As shown in simulation results, it is possible to guarantee an AF service that ensures contracted target rates and performs a fair share of the excess bandwidth.Este trabajo se enmarca dentro del proyecto CICYT FAR-IP (TIC2000-1734-C03-03)