Reduction of ONU buffering for PON/VDSL hybrid access networks
Today's growing internet traffic requires service providers to offer customers faster transmission rates. To keep up with such high transmission rates, service providers need to deploy fiber optical networks. However, due to the high cost involved in deploying the fiber media, this may not prove to be a feasible solution. Instead, service providers can deploy fiber media up to a distribution point, such as a customer's block, and continue the last few hundred feet using the already deployed legacy copper wire media. In our study we investigate downstream/upstream transmission coordination for passive optical network (PON) / Digital Subscriber Line (DSL) hybrid access networks. Our goal is to reduce the required buffer size at the optical network unit (drop point) that bridges the fiber and copper transmission media. We provide extensive experimental analysis, via analytical models and computer simulation, of various flow control mechanisms including: our novel GATED flow control, Ethernet PAUSE flow control and traffic Shapers. With our simulation models we can observe the performance tradeoffs in packet drops and packet delay when using reduced buffer sizes. We found a clear tradeoff between reducing buffer requirements with no or low loss and packet delay. We observed that at lower network loads, the PAUSE flow control and no flow control mechanisms provide a lower packet delay and a reduced buffer size compared to GATED flow control. However, at higher network loads, GATED flow control provides a more stable performance. The best solution is to activate the GATED flow control mechanism only when the network loads reach a certain threshold. Exploring this further serves as a promising path for further investigation.
Gurrola, Elliott Ivan, "Reduction of ONU buffering for PON/VDSL hybrid access networks" (2013). ETD Collection for University of Texas, El Paso. AAI1551225.