IEEE is currently standardizing a new high-speed backbone technology for MANs--Resilient Packet Ring (RPR). A key performance objective of RPR is to achieve high utilization, spatial reuse, and fairness simultaneously. However, the algorithms proposed in current draft standards have some critical limitations. As shown in unbalanced traffic scenario, drafts RPR algorithm will suffer from dramatic bandwidth oscillations within nearly the entire range of the link capacity. In this paper, we propose a new dynamic bandwidth allocation algorithm called Distributed Bandwidth Reallocated in Rings (DBRR), which is based on approximately virtual-time. It shows that with fairness information propagated along the ring, each node can remotely approximate the ideal fair rate for its own traffic at each downstream link, and the whole ring can obtain the maximum spatial reuse and nearly lossless throughput.
Metro edge is a critical part of end-to-end path
RPR can permanently oscillate in a wide range
Throughput loss is approximately 15% and is dependent on delays and filter settings
Root cause is unbalanced fair rates (vs. input rates)
DVSR as a high-performance, implementable approximation to RIAS fairness
Significant convergence time and throughput improvement of DVSR vs. RPR