Cable Makes Its Mark at FTTH Connect
Over the past two years, members of the CableLabs Optical Technologies team had the privilege to speak at the Fiber-To-The Home (FTTH) Council’s yearly FTTH Connect event. FTTH Connect annually attracts many thought leaders from both the vendor and service provider communities.
One observation we made while attending FTTH Connect was the growing appetite of FTTH Connect attendees to learn more about cable industry initiatives and solutions. Not only were the presentations well attended, but in one instance the Q&A session lasted for 30 minutes past the allotted time. Presentations provided FTTH perspective in a cable network, motivation for fiber deployments to complement the HFC network, PON traffic modeling, and supporting cable’s triple play services with fiber home run implementations. This appetite for more cable knowledge was somewhat surprising but welcome.
The impetus for CableLabs’ involvement was not only to show the world that the cable industry is pushing FTTH solutions, but also to introduce the FTTH community to CableLabs as a leader of innovation and R&D solutions. CableLabs has introduced several solutions to provide a means and support strategies of operators for pushing fiber deeper into the HFC network, including FTTH. These solutions include DOCSIS Provisioning of EPON (DPoE), Triple Play over PON and the group of specifications based on the Distributed CCAP Architecture.
Based on the show in 2015, we set out to increase our contributions at the 2016 FTTH Connect event. We proposed an entire cable track to the FTTH Council and were unanimously approved. We then set out to offer cable’s story at this year’s conference. It begins with Guy McCormick, Senior Vice President at Cox Communications, who will be one of the shows keynote speakers. Cox Communications is one of the most forward-thinking cable companies in the world, and they have an aggressive strategy around FTTH deployments. Jon Schnoor will discuss how we achieve fiber parity with cable services to that of the HFC access network. Steve Burroughs will present how to move beyond technology specific provisioning and work toward an access network agnostic infrastructure through virtualization. Curtis Knittle will explore next generation PON solutions that will establish 100 Gbps EPON and include an operator’s perspective on their transition to FTTH including challenges, technology tradeoffs, operational challenges and solutions. Curtis Knittle is also hosting a panel regarding FTTH in cable, that will explore an operator’s perspective.
If you’re planning to attend FTTH Connect 2016, be sure to attend the cable industry sessions to see what is cool and interesting!
Technology Implications of 2Gbps Symmetric Services
Service providers and municipalities alike continue their push toward offering gigabit services over fiber networks. In fact, fiberville is a web site dedicated to listing which service providers and municipalities provide fiber solutions. Recently, Comcast significantly upped the ante by announcing a 2 Gbps symmetric service that will become available in certain locations. The services announced will be 2 Gbps downstream and 2 Gbps upstream. This is a substantial announcement due to the 2 Gbps speeds and symmetrical services which facilitate faster file uploads which is of interest to individuals who work from home, small businesses and gamers.
With all that speedy yumminess, let’s examine some of the technologies required for delivering multi-gigabit symmetrical services to homes and businesses.
Setting the Stage
When a provider deploys broadband services there is typically a peak rate, above the advertised speeds, that provides the headroom necessary for them to support the speeds and service level agreements (SLAs) associated with the service.
When the total available bandwidth is shared among multiple users, like it is in PON solutions, an unscientific but common practice is for the network to support at least twice the highest advertised rate. Specifically, to support an advertised service of N Gbps, the peak rate must provide for at least 2xN Gbps. Thus, for a 2 Gbps service the peak rate must be at least 4 Gbps to safely support the SLA using common practices. This premise allows the operator to investigate and determine the technology to use in order to support the advertised speeds. Once the technology is chosen, then the engineering work required to build out the solution may begin.
Let’s look at the two fiber to the home solutions that will support a 2 Gbps symmetric service today: Point-to-Point Fiber and 10 Gbps Ethernet Passive Optical Network (10G-EPON).
Point to Point Fiber: Best Performance
Point-to-point topology is a “home-run” active Ethernet fiber implementation that provides dedicated fiber from the home all the way through the access network to the headend. It is analogous to building your own personal highway from home to your office so you can get to work faster. While this solution provides the ultimate future-proof network, in terms of bandwidth, flexibility and network reach, it requires a significant amount of fiber and associated optical transceivers. Running a dedicated fiber to a residential customer premise is both complex and resource intensive due to additional fiber management and ongoing maintenance. However, it delivers the best performance to meet customer needs.
10G-EPON: An Efficient 2-Gig Symmetrical Solution
While there are many flavors of Passive Optical Networks (PON), (see: OnePON), 10G-EPON with its symmetric 10 Gbps links, is the only standardized, and commercially available PON technology able to provide at least 4 Gbps peak rate to support a 2 Gbps symmetrical service level agreement. Because of its point-to-multipoint topology and passive implementation, 10G-EPON is a cost effective solution in terms of operations, fiber consolidation, and headend real estate required.
CableLabs has championed PON initiatives through contributions to international standards, hardware and software certification, and interoperability events. CableLabs is facilitating a common approach to provide fiber solutions that will allow for quicker and higher-scale PON deployments.
Both 10G-EPON and point-to-point fiber solutions can provide 2 Gbps symmetrical services, opening up a world of possibilities for cable operators and customers alike. From the realization of all-IP delivered services, more efficient network implementations, improved cloud services, and overall future proofing the network, 2 Gbps symmetrical fiber deployments are a reality today.
Jon Schnoor is a Senior Engineer at CableLabs.
OnePON™: Addressing the Alphabet Soup of PON
APON, BPON, EPON, GEPON, GPON, G.epon, NGPON1, XGPON1, XGPON2, NGEPON, NGPON2, TWDM-PON, WDMPON – did I leave any out? I’m sure I did.
The alphabetical possibilities to represent different versions of passive optical networking (PON) technologies will soon be exhausted. I’m being overly dramatic, of course, but trying to make the point that all these different versions of PON, driven by membership in two somewhat competing standards development organizations, not only causes the eyes of network engineers to glaze over, but has contributed to confusion and indecision among service providers globally.
What is a PON?
In the strictest sense, a PON is an all-fiber network which consists of only passive optical components (specifically splitters and combiners), except at the endpoints of each fiber, where there is an electrically-powered termination device – either an optical line terminal (OLT) or optical network unit (ONU). The aforementioned PON technologies also assume a point-to-multipoint topology in which downstream transmission from an OLT is received by all ONUs, but upstream transmission by an ONU is received only by the OLT.
Admittedly, not all of the acronyms above represent actual PON standards, so here is an unofficial, very short description of the meaning of each acronym:
APON (ATM PON) – The first PON technology standardized by the ITU. APON used Asynchronous Transfer Mode (ATM) cells to transport data across the PON. APONs typically provided up to 622 Mbps downstream and up to 155 Mbps upstream.
BPON (Broadband PON) – ATM is known to be an inefficient transport technology, so APON was renamed to BPON to distance the technology from ATM, even though it still used ATM for transport. Supported bit rate also increased to 1.2 Mbps downstream and 622 Mbps upstream, but most (all?) were deployed at 622 Mbps downstream and 155 Mbps upstream.
EPON (Ethernet PON) – The first PON standard developed by IEEE which uses Ethernet frames to transport data across the PON. 1G EPON provides symmetric 1 Gbps links, while 10G EPON provides symmetric 10 Gbps links. There is also a variant that provides 10 Gbps downstream and 1 Gbps upstream.
GEPON (Gigabit Ethernet PON) – Many people use GEPON to refer to EPON. Others use GEPON to refer to an early, unstandardized version of 100 Mbps PON used in Japan.
GPON (Gigabit PON) – A non-ATM based PON standard from the ITU which uses GPON Encapsulation Method (GEM) to transport Ethernet frames, ATM cells, and native TDM data across the PON. GPON provides 2.5 Gbps downstream and 1.25 Gbps upstream. ATM and TDM are de-facto obsolete, and no GPON equipment supports it, resulting in a network solution which also transports only Ethernet frames – like EPON.
G.epon (EPON with a GPON flavor) – Not to be confused with GEPON, which existed first, G.epon is an ITU term used for EPON devices which can be configured using the GPON mode of ONU configuration called ONU Management Control Interface (OMCI).
NGPON1 (Next Generation GPON) – ITU name for a family of 10 Gbps PON standards (see XGPON1 and XGPON2) – this was the first “next generation” activity in the ITU.
XGPON1 / XGPON2 (10G GPON) – XGPON1 represents an ITU standardized versions of GPON capable of 10 Gbps downstream and 2.5 Gbps upstream. XGPON2 was supposed to represent symmetric 10G bps GPON, but it was never completed.
NGEPON – This is the name for the current IEEE activity to define an EPON standard beyond 10 Gbps – the next generation of EPON.
NGPON2 – This is the name for the current ITU activity to define a family of post-10 Gbps GPON solution(s) - the second “next generation” PON effort in the ITU. The technology of choice for this new standard uses Time and Wavelength Division multiplexing – the origin of the TWDM-PON acronym.
I’m sure I missed a few hyphens in all those acronyms, but I give up! It’s definitely clear as mud, right? Actually, it is very challenging to explain all the different PON standards and terminology. The bottom line is, service providers today are forced to choose between two PON solutions that do exactly the same thing – transport Ethernet frames from one side of an optical distribution network to the other side. Judging from the NGEPON (IEEE) and NGPON2 (ITU) activities, it looks like the madness will continue and the industry will have two next generation PON standards to choose from, much to the disadvantage of both service providers and vendors.
Learning from the Wireless Industry
Once upon a time in the wireless industry there were several competing standards simultaneously operating: GSM, North American TDMA, and Qualcomm’s CDMA. In addition, around the year 2000, WiMax made an entrance. These competing standards operated for anywhere between 8 and 12 years. Around 2006 the GSM/TDMA/CDMA trifecta finally converged to become what is today the LTE wireless standard. The interesting aspect of this technology convergence is the affect on CPE dongle pricing, as shown in the graph below.
Clearly, a single technical solution drives prices downward much quicker by achieving truly global scale. This has been a huge benefit for wireless service providers. Also beneficial for wireless device vendors, they get to focus their precious and limited development dollars on a single technical solution for the entire wireless market.
Clearly the global telecommunications industry does not need two different technologies to transport Ethernet frames across a PON. Today, the IEEE and the ITU are both working on yet another generation of PON standards which will continue the alphabet soup trend and continue to bifurcate the PON market. If the wireless industry may serve as an example, this will force service providers to unnecessarily pay higher prices, and device manufacturers to spend nearly twice the amount for product development if they wish to target the entire market.
The CableLabs OnePON™ Initiative is building toward creating a single PON solution that satisfies the requirements of the global service provider market. OnePON™ is not EPON, and it is not GPON. A third standardized PON solution is not a goal of the OnePON™ Initiative. On the contrary, the goal is to combine the best aspects of both IEEE and ITU solutions to create a single next generation solution. Service providers will reap the benefits of lower capital expenses for network deployments. Vendors will be able to focus on a single technical solution for PON which addresses the global PON market, resulting in saving a tremendous amount of development costs (compared to two PON solutions), which will help translate directly to lower costs for service providers.
As Director of Optical Technologies at CableLabs, Curtis Knittle leads the activities which focus on standardizing EPON and GPON technologies for use in cable operator networks. On a daily basis he witnesses firsthand the challenges and increased costs associated with two similar PON technologies.