The Importance of Dynamic Bandwidth Allocation in GPON Networks
Abstract
This article describes Bandwidth Allocation in the PON network and highlights the advantages
of Dynamic Bandwidth Allocation (DBA). A well-defined DBA algorithm can significantly
improve network performance, provide a means of flexibly tailoring network responsiveness
and enable a service provider to generate more revenue from their FTTH networks without
boosting raw bandwidth by increasing the percentage of acceptable oversubscription.
A GPON Bandwidth Allocation algorithm allows the Optical Line Terminal (OLT) to control
upstream bandwidth allocation to the Optical Network Terminals (ONT). This article compares
currently available Bandwidth Allocation methods and their impact on the service provided to
the subscriber. By simulating a real-life TCP download scenario, it shows that Status Reporting
(SR) DBA is a superior tool to provide a high level of quality of service.
When using Static Bandwidth Allocation or Non-Status Reporting (NSR) DBA, operator
visibility into the upstream channel is limited. The PON access network can easily turn into a
bottleneck, limiting overall network performance, as the inability to control upstream latency
can result in latencies of 10mS and longer in the upstream channel alone. In addition, packet
loss is inevitable using NSR DBA. As a result, the operator cannot oversubscribe the network,
cannot provide symmetrical 100 Mbps services and cannot maximize its revenue potential.
SR-DBA provides excellent visibility into the upstream channel. When using SR DBA, tight
control reduces upstream latency by 90% and limits it to the 1mS range, enabling symmetrical
services at 100 Mbps and beyond. The SR-DBA supports oversubscription and can allocate
bandwidth equivalent to 5 Gbps and beyond, leveraging the traffic burstiness characteristics.
About PMC
PMC-Sierra is a leading provider of high-speed broadband communications and storage
semiconductors and MIPS-Powered processors for Enterprise, Access, Metro Optical Transport,
Storage Area Networking and Wireless network equipment. The company offers worldwide
technical and sales support, including a network of offices throughout North America, Europe
and Asia. The company is publicly traded on the NASDAQ Stock Market under the PMCS
symbol and is included in the S&P 500 Index.
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