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 .
Resilient Packet Ring is a new technology being standardized by IEEE 802.17 working group. This paper describes the ways to accomplish uniform traffic handling and spatial traffic handling by comparison. Since uniform shaping cannot avoid head of line blocking or decrease the jitter of bandwidth utilization on multiple chock point ringlet, this paper proposes a solution for shaping of spatial traffic handling. Virtual destination queues are introduced to the shaper to avoid HOL, and a special kind of dynamic priority is added to the scheduler to optimize bandwidth utilization. A simulation model is set up to exam the performance of VDQ aware shaper, which is the first phase to accomplish spatial shaping.