ONU buffer elimination for power savings in passive optical networks

In this paper, we examine the effects of a power saving scheme in Passive Optical Networks (PON). Buffers in network equipment have been a cause of concern since they consume significant power. In a PON, the Optical Network Unit (ONU) buffers client node packets before forwarding to the Optical Line Terminal (OLT). We propose a scheme that reduces or eliminates buffers in the ONU thereby providing reduction in cost and power. However, this can potentially increase the packet delay due to buffering at the client node. This paper analyzes the delay performance using simulated and theoretical models. The increase in delay due to buffering at the EN instead of the ONU is found to be less than 300 microseconds, for the studied workloads; the total packet delay is also less than 800 microseconds. This is within the access network delay budget (typically 2 milliseconds) for different traffic types and loads. © 2011 IEEE.