DPoE: What’s the buzz? Flexibility, interoperability are a few of the key features

Thu, 02/13/2014 - 7:45pm
Shridhar Kulkarni, product manager, access network solutions, Aurora Networks

Not only are consumers demanding higher speeds, higher service reliability, multi-screen services and high-definition TV (HDTV), operators are also facing the challenge of trying to maintain their competitiveness. One way for cable operators to maintain their lead and indeed increase their market share is to expand service offerings to commercial subscribers.

But deploying the technologies to deliver these next-generation services directly to businesses, which may include industrial parks and large office clusters, is by no means a small feat. While it may be a key opportunity, providing such bandwidth-intensive business offerings only adds to the already existing bandwidth constraints being faced by the industry. To stay ahead of the competition, continue to drive greater revenue and cost-effectively meet customer requirements, cable operators need solutions that can accommodate the heavy-bandwidth demands caused by these next-generation business services for not only today, but for the future as well.

In the past, operators have deployed commercial services using a point-to-point architecture, which has proven to be costly due to the higher fiber-count requirements in the plant and greater switching and aggregation port requirements in hubs and headends. Thus, the industry has begun to shift to favor a passive optical network (PON) and subsequently an Ethernet passive optical network (EPON) for commercial deployments.

Expanding role of EPON

With the commercial services opportunity, it’s clear that efficient use of EPON technology to reach an expanding base of customers will be the key to driving growth. Some of the more important trends underscoring this point include:

High-Capacity Data Transfers: Many business and institutional sectors, including health, education, financial and government, are leveraging the efficiencies of big data processing and storage technology to aggregate huge volumes of data for multiple uses across multiple access points. For example, school districts and local governments are now seeking to support centralized storage and distribution of video and other bandwidth-intensive content for libraries and classrooms as well as high-speed data interconnection of all facilities with central administrative offices.

PRI, SIP trunking and hosted PBX: Operators are responding to growing demand for low-cost multi-line voice services, including the commonly used 23-line private line interface (PRI) service traditionally delivered over T1 trunks. Session Initiation Protocol (SIP) trunking is now very popular with larger enterprises and this definitely presents an opportunity for cable operators. Hosted PBX, too, has become an important opportunity that leverages existing HFC plant as well as Ethernet fiber extensions to deliver low-cost PBX support from the cloud.

Metro Ethernet Services: The Metro Ethernet Forum (MEF) has standardized several umbrella service categories, each of which supports a wide range of specific applications and all of which require high bandwidth connections. With the ability to remotely scale bandwidth in increments as granular as 1 Mbps and as high as 10 Gbps, Metro Ethernet-compliant operators can deliver several classes of service backed by strong service level agreements.

Enterprise Video: The emergence of video as a linchpin to operations is one of the big drivers behind demand for high bandwidth among businesses of all types.

Cellular Backhaul: This service has been an important proving ground for operators in the use of Metro Ethernet. By virtue of cellular providers’ ever greater data transport requirements as they evolve from 3G to 4G networks, cellular backhaul promises to be a strong business for operators for some time to come, including repeat business with existing customers who will require more transport capacity.

And this is without considering the longer-term view in residential services.

The advent of the DPoE specification

Two years ago, member companies of CableLabs developed the DOCSIS Provisioning of EPON (DPoE) specification as an extension of the earlier DOCSIS certification programs with the goal of increasing interoperability and productivity, while providing cable operators with a means to deliver business connectivity services over fiber networks. In order to do this, the DPoE specification makes it possible to implement DOCSIS provisioning, as it is the prevalent technology for providing Internet and IP services over HFC networks. Furthermore, the DPoE system promotes wide-scale interoperability both from the perspective of vendor hardware and services deployment. It allows a mix of equipment from different manufacturers and adds functionalities that enable end-to-end provisioning and transport of advanced business service applications.

 While the development of the DPoE system has been relatively recent, its evolution has proven quite rapid. The initial DPoE specification, version 1.0, was completed in March of 2011 and focused on providing high-speed data and MEF Ethernet Private Line (EPL) services. This is the most common approach for using DOCSIS back-office provisioning processes to deliver business data services over EPON access networks, and is the standard that most chipset vendors currently implement.

Fast forward to late 2012 when the DPoE specification version 2.0 was released. Version 2.0 expanded the focus of the DPoE system to more complex services, including quality of service (QoS) capabilities and added requirements for features such as IPv6, multicast and service OAM. Additionally, version 2.0 included support for advanced MEF services such as Ethernet Virtual Private Lines (EVPL) as well as E-Tree and E-LAN architectures that enable multi-point-to-multi-point business connectivity, rather than having just a point-to-point architecture.

Today, DPoE does not address high-order services such as voice, IPTV, Wi-Fi, and residential gateway features. For residential PON deployments it will be imperative for operators to deploy these services over the top of the DPoE-laid pathways. It is also critical for vendors to offer seamless provisioning of these advanced services as elegantly as possible as part of the access network ecosystem.

Benefits to cable operators

The benefits of a DPoE network are extensive. As noted earlier, DPoE specifications enable wide-scale vendor and equipment interoperability. This not only coincides with DOCSIS back-office servers, but also with other suppliers’ equipment. As a result, DPoE optical network unit (ONU) suppliers can expect their products to interoperate with all others that adhere to the DPoE standard, regardless of what other devices are within the network.

Additionally, the continued use of DOCSIS provisioning makes it possible to send configuration information to millions of DOCSIS devices. Building on this, DPoE enables services to be managed just like those delivered over cable modem networks. EPON ONUs are provisioned just like a cable modem while the EPON optical line terminal (OLT) behaves like a cable modem termination system, offering the same IP service capabilities. In addition, by adhering to MEF services specifications, DPoE network devices provide architecture and requirements to support advanced business and Ethernet services applications. As a result, operators can roll out commercial services without the need to change costly technology such as existing back office software and operations support systems (OSS), and not to mention all the people trained in those technologies.

DPoE standards are great enablers that are assisting the cable industry’s goal of attaining all-fiber, all-IP networks to serve commercial subscribers – while reusing much of their back-office investment. However, while DPoE networks already have the potential to provide cable operators with extensive benefits, there are opportunities to go above and beyond what is currently offered. For example, to remain competitive, cable operators must provide additional service offerings along with data, such as voice and Wi-Fi, which currently are outside the scope of DPoE specifications.

To DPoE networks… and beyond

 The good news is that there are independent, augmented solutions that can elegantly integrate into the DPoE ecosystem, thus facilitating high-order services provisioning.

Clearly, the ability to maximize the benefits of a DPoE system as new specifications emerge is important to an operator’s growth potential in EPON services. But so, too, is the ability to leverage existing infrastructure and advanced operations tools to maximum advantage in the extension of EPON services to ever larger segments of the market.

Operators should look for cable-optimized EPON technology; there are portfolios of solutions available today, including distributed OLT technology, optimized for deployment in fiber optic nodes, that enables operators to continually expand the reach and range of service options while minimizing capex and opex costs.

By developing the means by which cable companies can leverage their current network investments to support a variety of migration paths for EPON in commercial and ultimately residential markets, there is now a framework for operators to cost-effectively expand services as new opportunities arise. No matter what path chosen, there will be assurance that they can use management tools native to the services and devices they offer.

The creation of DPoE specifications has made it much easier for operators to provision and manage their EPON services. With a DPoE-compatible framework, operators can use their DOCSIS management tools to automate operations across all DOCSIS-related and Metro Ethernet service categories, and in special cases, including those that have yet to be addressed by DPoE specifications.


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