Optical-fiber access networks are reaching more business enterprises and consumers every day. Still, for most businesses, fiber access will not be a reality for many years, while the demand for the bandwidth for services fiber can provide is already very real today.

Carriers are committed to Ethernet access evolution and cannot afford to be limited by the media by which they reach their customers. Their business enterprise customers want high-bandwidth, resilient, Quality of Service (QoS)-guaranteed applications such as Internet Protocol Virtual Private Network (IP-VPN), Voice over IP (VoIP), and transparent local area networks (LANs), and, for their own competitive concerns, they want them today.

Legacy access networks pose an obstacle in these revenue opportunities for carriers. Time Division Multiplexing (TDM) transport in the access network for data services can fail to deliver on customer expectations for bandwidth and service performance, creating significant operational expenses for carriers.

However, a maturing class of multi-service Carrier Ethernet solutions changes the equation -- offering the service performance and cost-effective scalability that carriers require even in areas where fiber access to customers is not yet available. Providing the flexibility to offer Ethernet over copper, TDM, or fiber facilities, they position a carrier to successfully compete wherever it is along the path of Ethernet access evolution.

The Gaping Hole Between Fiber and Copper Technologies
Tier 1 carriers seek to extend superior levels of efficiency and service capability throughout their footprint, and competitive local exchange carriers (CLECs) are urging the Federal Communications Commission (FCC) to protect their access to customers via copper and fiber. With fiber being the long-term future of carrier access networks, all service providers are preparing themselves for that competitive fact.

Nonetheless, a lack of fiber connections to many businesses, homes, and mobile cell-site towers continues to set up a huge revenue opportunity today for service providers who can deliver leading-edge, high-bandwidth Ethernet services via legacy access media and battle cable operators for business in the “fiber gap”. More than 75 percent of U.S. business Ethernet services reached users by access media other than direct fiber in 2009, according to Vertical Systems Group (www.verticalsystems.com). And the legacy business opportunity is unlikely to disappear soon, especially for lower-speed services. Vertical Systems Group forecasts that copper connectivity will shoulder a sharply rising percentage of sub-10 Mbps services, reaching nearly 10 times as much as will fiber by 2013. Carriers for the foreseeable future must continue to be capable of delivering a wide range of service options across the full gamut of access media, copper, and fiber.

Ratification of IEEE 802.3ah Ethernet in The First Mile in 2004 standardized Ethernet service delivery over widely installed, legacy copper access infrastructure. EFM delivered a critical breakthrough for the industry. Ethernet access is so much more affordable, more flexible, and easier to scale than Asynchronous Transfer Mode (ATM) or Synchronous Optical Network (SONET) approaches. Even more importantly for carriers, EFM enabled service providers to increase bandwidth and service options to most of the subscribers in their footprint.

Since then, ongoing innovations in EFM solutions have steadily enhanced carrier capabilities and efficiencies. Carrier Ethernet equipment has become more powerful, more reliable, smaller, more energy-efficient, and easier to install and use. Most recently, multi-service platforms have emerged that enable any Ethernet service to be introduced over any access media from the same chassis. These multi-service platforms enable a seamless migration from traditional, expensive TDM-centric delivery of Ethernet services to end-to-end, IP-based delivery -- future-proofing service providers for their Ethernet access evolution. (See Figure 1.)

Figure 1. TDM-to-Ethernet Migration.

Bridging the Gap: Multi-Service Carrier Ethernet Benefits
The emergent multi-service Carrier Ethernet platforms enable ubiquitous Ethernet service delivery and competitive service-creation velocity across existing copper and TDM infrastructure, in addition to fiber. These capabilities expand a carrier’s immediate market opportunity for cost-effectively serving business and institutional customers by an estimated 10-fold. A carrier simply surveys the physical media available across its customer base and strategically deploys the best possible services for the lowest possible operational expenses, easily migrating to fiber-based delivery in the future. (See Figure 2.)

Figure 2.  Ethernet services over any infrastructure to any location.

By supporting all Metro Ethernet Forum (MEF) service models (E-LINE, E-LAN, and E-TREE) the new multi-service Carrier Ethernet platforms enable pay-as-you-grow rollout of a complete range of legacy and next-generation services, such as:

• wholesale offerings
• Ethernet business services via copper or fiber
• digital subscriber line access multiplexer (DSLAM) backhaul
• dedicated Internet access
• private lines
• layered VoIP transport
• multi-tenant Ethernet
• mobile backhaul

In introducing next-generation Ethernet offerings and transitioning away from legacy ATM- and SONET-based services, carriers must not jeopardize current revenue streams by compromising on the carrier-class qualities that have grown customary of established services. For example, the ability to deliver and guarantee multiple service-level agreements (SLAs) per subscriber is critical. And, in the case of an Ethernet mobile backhaul service across the Last Mile connection between a mobile communications tower and exchange center, any mix of native Ethernet and native TDM voice must be delivered simultaneously while maintaining all of the key performance characteristics (delay, jitter, timing, etc.) of a conventional T1 connection. Ultimately, the call quality must be indistinguishable.

While carriers are firmly committed to expanding their fiber access networks to more and more of their enterprise, residential and wholesale customers, there can be no waiting for state-of-the-art services in the interim. Multi-service Carrier Ethernet enables a carrier to strike this important balance.

Maturing Solutions Key Features
As the need for multi-service Carrier Ethernet solutions has grown increasingly clear, the systems have grown increasingly sophisticated in terms of factors such as ease of use, reliability, and troubleshooting. Carriers must achieve a faster time to service for new customers, prevent customer churn by minimizing service downtime, and contain long-term operational costs.

The emergent multi-service Carrier Ethernet has matured to deliver key features and functionality in these areas:

1. High-performance Ethernet switching and simplified service creation.

2. Architecture flexibility, such as the capability to deploy Ethernet services across any media type, copper and fiber.

3. Full front-access design in a modular configuration.

4. Low power consumption with a small-chassis footprint.

5. Temperature hardening.

6. Flexible deployment options such as vertical/horizontal mounting and equal suitability for central offices, controlled environmental vaults, outside plant remote terminals, cell sites or customer locations.

7. Plug-and-play configuration of "zero-touch" customer-premises equipment (CPE).

8. Advanced Time Domain Reflectometer (TDR) capabilities for simplifying copper qualification.

9. Transport of Ethernet and TDM traffic in their native format with full network timing.

10. Sophisticated, hierarchical QoS functionality and rate-reach tools.

11. Flexible and scalable bonding engine.

12. Macros for automating routine tasks.

13. Management based on command-line and graphical-user interfaces.

14. No single point of failure.

Many carrier requests for proposals (RFPs) are now demanding these types of system characteristics in order to streamline the work of telecommunications engineers, designers, planners, outside plant managers, and deployment professionals. The lasting impact is a low total cost of ownership (TCO).

Gap Is Gone!
Many carriers have typically operated separate systems from multiple vendors for transporting Ethernet services over fiber, copper, and TDM bonded circuits. Some carriers have achieved return on investment (ROI) within 6 months of deploying a solution such as Hatteras Networks' multi-service HN6100 to consolidate their disparate service traffic.

Deploying a single multi-service Carrier Ethernet solution to support all of its Ethernet services moving forward enables a carrier to greatly simplify operations and cut ongoing operational costs. By transitioning to transparent Ethernet services for voice and data business connectivity and infrastructure backhaul solutions over either existing or future access facilities, the carrier gains a more efficient, cost-effective strategy to scale for bandwidth growth while keeping its customers availed to service innovations as they emerge. At the same time, the carrier positions itself to cost-effectively pursue Ethernet service revenue opportunities throughout its service footprint today while adopting a gradual, pay-as-you-grow strategy to Ethernet access evolution.

About the Author
M. Vijay Raman serves as Vice President of Product Line Management and Marketing for Hatteras Networks. Since Mr. Raman joined Hatteras in Q4 2008, he has successfully launched 6 products including the HN6100 multi-service Ethernet switching platform which garnered 8 Product Review/Awards since October 2009. For more information, email: vraman@hatterasnetworks.com or visit www.hatterasnetworks.com.

What’s In an Ethernet Service?

Ethernet services are becoming more and more ubiquitous each year, and you may be wondering what type of Ethernet service is right for you. As part of its far-reaching work in the definition and promotion of Ethernet services, the Metro Ethernet Forum (MEF) has defined 3 basic types of Ethernet services, each providing a different kind of connectivity for your potential use.

Types of Ethernet Service

E-Line
An E-Line service is the Ethernet equivalent to a traditional point-to-point TDM circuit. An E-Line service provides connectivity between exactly 2 endpoints, and attempts (as much as possible) to mimic a direct Ethernet cable between 2 sites. An E-Line service can be used anywhere a traditional TDM (T1, E1, SONET, etc.) service is used.

E-LAN
For those familiar with Ethernet in the enterprise, the E-LAN service is probably the most familiar. An E-LAN service provides multipoint connectivity between any number of endpoints in a virtual mesh -- where any endpoint can communicate directly with any other endpoint. An E-LAN service can be very useful in serving a business customer with more than 2 locations: it provides a clean Layer Two connection between all of the sites.

E-Tree
An E-Tree service may be more commonly known as a hub-and-spoke service. An E-Tree is derived from an E-LAN service in that it connects any number of endpoints together, but it differs in that certain endpoints are designated as roots of the E-Tree. The roots of the E-Tree (there can be multiple) can talk to any endpoint in the tree, whether it is another root or a non-root (leaf) endpoint. The leaves can only talk directly to root endpoints; leaf endpoints cannot talk directly to each other. An example where this service architecture is useful is in a residential ISP application, where one router feeds many customers. An E-Tree would allow each customer to talk to the router (or redundant routers), but would not allow customers to directly connect to (or attack) other customers.

These 3 service types form the foundation for all Ethernet services, and allow you to choose the connectivity that best fits your needs: point-to-point, multipoint-to-multipoint, or point-to-multipoint. Once you’ve decided the type of connectivity you need, there are many other options to consider: how you want to handle VLANs over your Ethernet hand-offs, what kind of QoS you need, how you want to handle specific Layer Two control protocols that might not be transparent to your carrier’s network, etc.

All of these options and variations are discussed in length in the tutorials and white papers available on the Metro Ethernet Forum website. Go to http://www.metroethernetforum.org and follow the links to the Information Center to learn more.

Matt Squire is Senior Vice President of Engineering and CTO for Hatteras Networks, a provider of Ethernet-over-copper access solutions for Metro Ethernet networks. Dr. Squire has more than 15 years of experience in developing and promoting Ethernet standards and technologies, and is a board member for the Metro Ethernet Forum. For more information, visit www.hatterasnetworks.com.

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