Our study is motivated by the need for per-flow fairness in a ring aggregation network. This paper proposes a multicolor marking and queuing delay suppression scheme called N rate N + 1 color marking (NRN + 1 CM) that is designed to achieve per-flow fairness. The key idea is to assign a color to a frame according to the flow input rate with high burst tolerance using a simple marker. The color indicates the dropping priority. When congestion occurs, frames are selectively discarded based on their color and the dropping threshold. The accumulation of queuing delay is suppressed with a dropping threshold notification process. The effect of NRN+1 CM was confirmed by a theoretical analysis and computer simulations.

A cascade aggregation can enable access networks to be deployed efficiently in areas with a low subscriber density. To achieve fairness for best effort (BE) traffic from subscribers, we proposed N rate N+1 color marking (NRN+1CM). However, it is important to realize weighted fairness. Network operators often provide different services that limit the maximum bandwidth or ensure that bandwidth is allocated with appropriate weights. This paper proposes weighted NRN+1CM which can set the maximum bandwidth and the weight for each subscriber and to allocate bandwidth based on the weights. The proposed algorithm modifies the color generation probability with the weight. If the input rate exceeds the maximum rate, frames are discarded to limit the output rate. We confirmed the effect of the proposed algorithm from computer simulations. The throughput ratio matched the weights and the throughput was limited to the maximum rate regardless of changes in traffic.

With cascade aggregation, which can enable access networks to be deployed efficiently in areas with a low subscriber density, the problem arises of unfairness of Best Effort (BE) traffic between subscribers. This paper proposes an N rate N+1 color marking (NRN+1CM) function for achieving bandwidth fairness on cascade aggregation. The basic idea behind NRN+1CM is to color subscribers' BE frames and discard BE frames based on queue length and frame color. Multicolor markers have been studied but existing multicolor markers cannot estimate burst traffic rates accurately. We propose a multicolor marker with a single token bucket. The proposed marker can select a color from N+1 colors according to the traffic rate, independent of burstiness. NRN+1CM is scalable because it works on a simple queue configuration without messaging between layer-2 switches. Numerical simulations show that NRN+1CM can select colors accurately and achieve approximately fair bandwidth sharing.

In Ethernet Passive Optical Network (EPON) systems, Dynamic Bandwidth Allocation (DBA), which is based on the queue status request via REPORT massages, is one of indispensable functions in order to provide fair and high bandwidth utilization. However, REPORT messages does not always contains the same values even if the same REPORT formats are used in the same queues size condition because the contents of REPORT messages are not concretely specified and remains some flexibility. In this paper, in order to solve this issue and improve EPON interoperability, we propose the diversity DBA method that can accommodate various ONUs with different REPORT implementation. The diversity DBA has two functions that are discrimination of REPORT implications and fair bandwidth allocation for any ONUs with different REPORT implications. Moreover, we simulate the bandwidth allocation based on the diversity DBA and show their successful results to confirm its validity.