Future Generation Computer Systems 19 (2003) 313–326 QoS and SLA aspects across multiple management domains: the SEQUIN approach Christos Bouras a,b,∗ , Mauro Campanella c , Michal Przybylski d , Afrodite Sevasti a,b,e a Department of Computer Engineering and Informatics, University of Patras, 26500 Rion, Patras, Greece b Computer Technology Institute, 61 Riga Feraiou Str., 262-21 Patras, Greece c INFN-GARR, Via Celoria 16, 20133 Milan, Italy d Poznan Supercomputing and Networking Center, ul. Noskowskiego 10, 61-704, Poznan, Poland e Greek Research and Technology Network, 56 Mesogion Av., 11574 Athens, Greece Abstract The aim of this work is to define and implement an end-to-end approach to quality of service (QoS), operating across multiple management domains and exploiting a combination of link layer technologies. The architecture for the Premium IP service is presented, which aims at offering the equivalent of an end-to-end virtual leased line service at the IP layer across multiple domains. Also, the results of the initial testing performed for the validation of the service and the provisioning model for Premium IP are described. The work presented has been carried out in the framework of SEQUIN, a European Commission-funded research project. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Quality of service; Premium IP service; Differentiated services; Service level agreement; Monitoring 1. Introduction The need to support differentiated quality of service (QoS) has been recognized since the creation of the previous generation backbone networks and has been delivered, until recently, using ATM technology. How- ever, with the advent of gigabit networks, ATM alone is no longer available to deliver end-to-end service dif- ferentiation and QoS. The availability of high-speed ∗ Corresponding author. Present address: CTI, PO Box 1122, Patras 26110, Greece. Tel.: +61-960375; fax: +61-996314. E-mail addresses: bouras@cti.gr (C. Bouras), mauro.campanella@garr.it (M. Campanella), michalp@man.poznan.pl (M. Przybylski), sevastia@cti.gr (A. Sevasti). transmission media and networking equipment, as well as the evolution of quality-demanding applications op- erating over the Internet protocol (IP) have raised inter- est in the provision of advanced quality services at the network layer, in addition to the traditional best-effort service of the Internet. In the research field, a number of alternatives for service differentiation and QoS provision have been proposed and standardized, but in the case of backbone networks, the Differentiated Services [2] architecture has prevailed, due to its scalability and deployment feasibility. The DiffServ framework stands out by at- tempting to provide service differentiation to traffic in a scalable manner, featuring the aggregation of indi- vidual application flows with similar quality needs. It introduces the definition of different service classes to 0167-739X/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0167-739X(02)00156-5