The IEEE 802.17 Working Group has taken another step forward in providing standards to Resilient Packet Ring (RPR) architectures by approving draft 2.4 of the RPR standard. Some companies have already had their RPR equipments for good market perspectives before the final standardization of RPR specifications. These equipments can supply services such as Ethernet Private Line (EPL), Transparent LAN Service (TLS), Ethernet Line Aggregation (ELA) and so on. Quality of Service (QoS) is an important part implemented in these equipments. Only when there is promise of QoS for RPR equipment, can commercial clients put their key applications to its network. Both the edge and the ring of RPR equipment need take QoS into effect to get QoS guarantees. This paper mainly deals with edge QoS study of RPR equipment. Policing, classification, shaping, and scheduling that are used for edge QoS process are introduced in the paper. And a QoS process method for traffic across rings is discussed at the same time.
This paper evaluates the performances of the contention-based channel access mechanism of IEEE 802.11e, called enhanced distributed coordination function (EDCF), compared with the 802.11 legacy MAC in supporting voice, video and data applications through network simulation of a scenario of 802.11e. Then we discuss the effects of Contention Window (CW) and Arbitration Inter-Frame Space (AIFS) on service differentiation and total throughput. We also consider an optional feature of the EDCF, called contention-free burst (CFB). Through our simulation study, we can draw a conclusion that the EDCF with TXOP can provide better-differentiated channel access for different traffic types than EDCF without TXOP especially at high traffic load conditions. But the movements caused by the parameters in CFB seem a lot bouncing and instability when in different application and configuration.
The Resilient Packet Ring (RPR) IEEE 802.17 standard is under development as a new high-speed backbone technology for metropolitan area networks (MAN) . Bandwidth reclamation has been concerned in RPR specifications from draft 0.1 to draft 2.4. According to specifications, allocated bandwidth can be reused, or reclaimed, by a lower priority service class whenever the reclamation does not effect the service guarantees of any equal or higher priority classes on the local station or on any other station on the ring . The class-based queuing (CBQ) algorithm is proposed to implement link-sharing . A hierarchical link-sharing structure can be used to specify guidelines for the distribution of 'excess’ bandwidth  and it can rate-limit all classes to their allocated bandwidth. There is some sameness between the link-sharing of CBQ and bandwidth reclamation of RPR. The CBQ is a mature technology while RPR is a new technology. Given CBQ improvement and full use so as to make its thought suitable for bandwidth reclamation of RPR is the focus of our work. In this paper, we present the solution that can solve the reclamation problem, which proves to be effective by simulation.
Resilient Packet Ring (RPR) is a newly developed Layer 2 access technology for ring topology based high speed network. Fairness Algorithm (FA), one of its key technologies, takes responsibility for regulating each station access to the ring. Since different methods emphasize particularly on different aspects, the RPR Work Group have tabled several proposals. This paper will discuss two of them and propose an improved algorithm, which can be seen as a generalization of the two schemes proposed in  and . The new algorithm is a distributed algorithm, and uses a multi level feedback mechanism. Each station calculates its own fair rate to regulate its access to the ring, and sends fairness control message (FCM) with its bandwidth demand information to the whole ring. All stations keep a bandwidth demand image, which update periodically based on the information of received FCM. The image can be used for local fair rate calculation to achieve fair access. In the properties study section of this paper, we compare our algorithm with the two existing one both in theoretical method and in scenario simulation. Our algorithm has successfully resolve lack of the awareness of multi congestion points in  and the drawback of weakness of fault tolerance in .