01889nas a2200145   4500008004100000245010300041210006900144300001500213520128100228100002101509700002201530700001901552700001601571856015601587       2004                        eng d00aProviding and verifying advanced IP services in hierarchical DiffServ networks - the case of GEANT0 aProviding and verifying advanced IP services in hierarchical Dif  a 321 - 3363 aThe differentiated services (DiffServ) framework is widely proposed as an efficient method for providing
advanced IP services to large-scale networks, with QoS requirements. However, the provisioning of such
services in production networks has proved to be more difficult than initially expected, in defining, setting
and verifying appropriate Service Level Agreements (SLAs). GEANT, the Gigabit core pan-European
research network, on a pilot basis introduced ‘Premium IP’ service, offering bounded delay and negligible
packet loss to the European National Research & Education Networks (NRENs) that it interconnects.
However, large scale provisioning of this new service requires the definition of efficient interaction
procedures between administrative domains involved and methods for SLA monitoring. This paper focuses
on these issues and presents the experience acquired from the early experiments in GEANT, as an example
of hierarchical Gigabit multi-domain environment, enabled with QoS provisioning to its constituent
NRENs. This model scales more efficiently than the common peering Internet Service provider (ISP)
commercial paradigm. Finally, we outline other options that promise QoS, such as Layer 2 VPNs in MPLS
backbones, with non-standard (yet) mechanisms.1 aBouras, Christos1 aSevasti, Afroditi1 aLiakopoulos, A1 aMaglaris, B  uhttp://telematics.upatras.gr/telematics/publications/providing-and-verifying-advanced-ip-services-hierarchical-diffserv-networks-case-geant?language=en