WHITE PAPER Future-Proofing BPON Architectures for Tomorrow’s GPON and N-GPON Future-Proofing BPON Architectures for Tomorrow’s GPON and N-GPON As the final touches are added to Gigabit Passive Optical Network (GPON) standards and with next-generation GPON (N-GPON) standards already underway, it should be clear to service providers that additional network upgrades are imminent as demand for bandwidth continues to increase. Today’s fiber-to-the-premise (FTTP) architectures, deployed with broadband PON (BPON) technology, are meeting the needs of small business and residential customers, but are they being constructed with easy upgradeability once bandwidth usage demands it? ADC believes there will be a logical migration from BPON to GPON architectures in coming years, followed by a similar move to N-GPON for even more bandwidth delivery. The question for service providers and network engineers is simple – have you considered the necessary steps for today’s BPON to enable the smoothest, most cost effective migration to GPON and, ultimately, N-GPON? The ultimate goal When deploying PON architectures, much of the cost is directed toward the infrastructure of fiber deployment and electronics. With that in mind, ADC is alerting network planners that the ultimate goal is to build PONs so the next upgrade is only a matter of replacing the electronics at each end of the network. Adding new services to the existing network should be achieved without having to change or re-deploy any infrastructure between the central office (CO) and the premise. The motivation for migration to GPON lies in its additional capabilities. As demand for bandwidth and cutting edge services rises, GPON offers many advantages. One of these advantages is a significantly higher data rate. BPON transports data at 622 Mbits/sec downstream and 155 Mbits/sec upstream. A move to GPON would increase those rates to 2.4 Gbits/sec downstream and 1.2 Gbits/sec upstream. GPON also provides for higher split ratios to service more homes. A centralized BPON system uses 1x32 splitters to service up to 32 customers. GPON offers a 1x64 split enabling up to 64 customers to be serviced from a single splitter. This splitter upgrade makes it relatively easy for service providers to opt for centralized splitter configurations. However, it could involve a significantly higher investment for service providers deploying cascaded splitter architectures, such as 1x4 splitters feeding 1x8 splitters – another important consideration for network architects deploying new PONs. GPON is expected to span greater distances, an ongoing issue in FTTP deployments. The GPON standard promises enhanced interoperability, support for legacy services, and physical interconnect conformance and performance. Each of these issues makes it important for service providers to ensure the PON networks they are deploying today will easily and cost effectively scale to GPON and other future standards. Page 3 Future-Proofing BPON Architectures for Tomorrow’s GPON and N-GPON The actual components deployed in today’s PON systems – connectors, cables, splitters, etc. – are already GPON- capable. These components have the capacity to carry many types of signals, from BPON to GPON. This could hold true for migration to N-GPON as well. Discussions about adding CWDM as one method of N-GPON migration could present additional technical challenges. Adding WDM to PON architectures will present significant issues, such as different band passes, using low water peak fiber, splitters for specific transmission ranges, and the need to accomplish testing in different band passes. For example, today’s BPON and GPON systems operate in the 1310 and 1490 nm ranges (and sometimes at 1550 nm in the case of video overlays). N-GPON may introduce new band pass ranges. ADC products already support wavelength ranges from 1260 to 1625 nm. However, even if the equipment can handle new band pass ranges, it’s still critical for network planners to look ahead toward other issues associated with migrating the network to GPON or N-GPON. For example, when BPON customers demand new services associated with GPON technology, the network should be as prepared as possible to accommodate them. Choosing the proper fiber distribution hub (FDH) – one with extra splitter slots for easy expansion – and the right splitter modules for BPON will decrease costs associated with future upgrades to GPON or N-GPON. Getting GPON services to BPON customers The real challenge lies in how quickly and easily the service provider can bring new GPON services to customers that demand them – and how to handle customers who are happy with the current services and don’t want to upgrade. Once the decision has been made to upgrade from BPON to GPON, the cost of delivering new services falls on either the customer or the service provider – and some customers won’t be willing to pay for services they don’t need. Therefore, it’s important to plan a migration to GPON that will ensure the satisfaction of all customers – and that will depend on how the BPON is constructed from day one. For example, a service provider for a 5000-home community has a very high take rate – 4500 homes are purchasing BPON services today. In-house marketing studies indicate that as many as 40%, would be willing to purchase additional services associated with a GPON upgrade. During the marketing campaign, the first 10% of those customers indicated they would be ready to purchase services within the first few months. This poses an interesting scenario – one that is entirely dependent on how the BPON was originally designed within the network. The first step is to install a GPON-capable optical line terminal (OLT) in the CO to support the new GPON services. The 10% of customers taking the services would need their BPON optical network terminals (ONTs) at the side of their homes replaced with GPON ONTs. This will also require going to the FDH to install a new splitter associated with the GPON card. The distribution fiber (F1) now extends from the CO to the FDH and through the new GPON splitter. The final step is to switch each customer connection from the BPON splitter – thus removing that BPON port from service – to a new GPON splitter port. Although this may seem relatively easy, the service provider could incur significant expense during this process if the FDH was not installed with a migration in mind. The migration-minded FDH The first consideration for a migration-ready FDH is to ensure crossconnect capability – the ability to connect from any splitter port to any customer. Installing a centralized splitter architecture from the start will make this a much easier – and less costly – process. Individual drop cables can simply be swapped from BPON to GPON splitter ports for customers desiring the new services. A second consideration can be easily overlooked during an original PON deployment, but becomes clear when faced with a future upgrade to GPON. Ensuring that extra splitter slots are available in the FDH to enable easy installation of new GPON splitters – without having to remove BPON splitters to free up slots. Without spare splitter slots, a high take rate would require waiting until 32 customers were ready to upgrade, taking them all out of service, and replacing a BPON splitter with a GPON splitter in the same slot. The alternative would be to simply convert from BPON to GPON for all customers, even those that do not desire new services. However, that would also require changing out the ONT at every home – a very expensive proposition. The importance of extra splitter slots in the FDH is clear to allow easy and efficient migration of individual customers from BPON to GPON. In fact, ADC suggests as much as a 50% increase in available splitter slots to allow fast and affordable upgrades. Extra splitter space also enables providers to reclaim BPON splitters for future use in other portions of the network. These benefits can only be realized by deploying an FDH with additional splitter slots available. Finally, there may also be a need for additional “parking space” in the FDH to enable easier crossconnect activity. A parking lot can be used to place out-of-service cables temporarily while maintenance and customer churn issues are resolved. It not only provides an extra convenience to the technician, but helps keep connectors free of debris that could affect operating performance. WHITE PAPER Website: www.adc.com From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 • For a listing of ADC’s global sales office locations, please refer to our website. ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 106061AE 2/08 Original © 2008 ADC Telecommunications, Inc. All Rights Reserved WHITE PAPER Extra is better ADC’s message to service providers is simple – plan for the future. Deploy PON systems with interconnect capability in architectures that achieve the highest reliability and flexibility. Add extra slots in each FDH for additional splitters and more parking space for easy access and to accommodate any foreseeable take rate during an upgrade. Consider the cost savings of reclaiming used splitters for future use. It may be ten years away – or perhaps less than five – but sooner or later every FTTP network will require some type of upgrade. Planning for an upgrade as an inevitable reality, rather than just a remote possibility, is ADC’s position. Proper planning can make the transition faster, less expensive, and increase customer satisfaction. Ensuring the FDH is migration-ready will make all the difference. . PAPER Future-Proofing BPON Architectures for Tomorrow’s GPON and N -GPON Future-Proofing BPON Architectures for Tomorrow’s GPON and N -GPON As the final touches. BPON to GPON architectures in coming years, followed by a similar move to N -GPON for even more bandwidth delivery. The question for service providers and