Fairness with N Rate N+1 Color Marking on Cascade Aggregation for Access Network

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.