Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Conducted and analysed QoS tests in both local testbed and 6NET's QoS-enabled IPv6 network

The first set of tests investigated how it is possible to implement a QoS service that is suitable for real time applications. The QoS service under testing was based on DiffServ EF (expedited forwarding) PHB, which provides strict priority to properly marked packets. The second set of tests investigated the "intra-class fairness" for AF (assured forwarding) traffic, i.e. how does (free) link capacity is efficiently shared among different flows in a (partially) congested network. The third set of tests investigated the combined operation and interaction of different QoS mechanisms, such as traffic policing, traffic shaping and class-based queuing. These mechanisms are usually applied on edge routers at the interface towards the network provider network. Therefore, inappropriate tuning of these mechanisms may severely affect services provided. The last set of tests investigated the performance achieved by data transfer applications that used Less that Best Effort (LBE) services in a production network.

The second phase of QoS tests took into account the defined QoS model and extended the QoS activity across 6NET’s backbone network. Initially, the proposed QoS model, which is based on the Differentiated Services (DiffServ) architecture, was studied taking into account several aspects, such as network dimensioning, policing and admission control. In particular, the 6NET QoS model includes the implementation of the IP Premium service, which is based on the EF (expedited forwarding) PHB (Per Hop Behavior) and provides absolute prioritization to this type of traffic. It also includes the BE (Best Effort) and the LBE (Less than Best Effort) services.

Afterwards, the appropriate configuration to allow 6NET to provide QoS services was formed and possible conflicts with other network services were identified. The configuration was applied to all 6NET’s backbone network routers providing the aforementioned QoS services to the connected NRENs. Finally, a number of tests were defined in order to evaluate the performance of the QoS services in the 6NET network. The prioritization of IP Premium traffic was examined, by testing the marking, traffic policing and traffic shaping mechanisms. A wide range of scenarios with various patterns of foreground and background traffic were performed in order to thoroughly investigate the applied QoS model and its impact.

The performed QoS tests in 6NET backbone indicated that this IPv6 QoS model can be the basis for production services. The mechanisms under test operated efficiently, as the experimental results prove, without any performance degradation on backbone routers. The above observations remained true even in heavy network congestion and the final performance results that a user or an application experienced correspond to the QoS service’s specification.

Reported by

University of Patras and Research Academic Computer Technology Institute
PO Box 1122
26504 PATRAS
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