Metro Ethernet

Metro Ethernet is a type of Carrier Ethernet used for the creation of metropolitan area networks (MANs). Used to connect a community, an academic environment, or a large corporation in a single wide area network or the Internet, the technology’s high degree of scalability allows it to accommodate very large areas. Until fairly recently, larger metropolitan areas were served with SONET/SDH, which delivered high speeds and strong performance across great distances, but at great cost. The development of carrier-class Ethernet has made it possible to accomplish the same thing for substantially lower cost from both an operating expenses, and capital expenses perspective. In the first early experiments of Metro Ethernet, carriers were reluctant to use Ethernet as a carrier technology. But two factors made it possible; that standard, best-effort Ethernet has more recently been embedded with high-end characteristics, and also the fact that Ethernet is already widely used in most enterprise installations.

Most carrier Ethernet MAN technologies today can support up to 40 kilometers using single-mode fiber. In addition to use in private government agencies, multi-site universities, and larger corporations, Metro Ethernet is being employed by some carriers which have chosen to phase out SONET deployments in favor of the less expensive Metro Ethernet option.

Replacement of SONET with Metro Ethernet is becoming even more attractive as higher Ethernet bandwidths become common, and Metro Ethernet incorporates standards for Quality of Service and self-restoration. One of the most attractive elements of SONET was its self-healing function; Carrier Ethernet now competes effectively with that through its own end-to-end restoration facility.

Already, Metro Ethernet is changing the way large organizations communicate, through a highly standardized and proven platform. It is already in wide use throughout much of the Asia-Pacific region, especially in India and China; and delivers significant cost savings to corporate users.

The basic design of Ethernet has long been used for LANs, but limitations on cable length—especially in higher speeds—long made it impossible to extend Ethernet to a metropolitan area. The development of a carrier-class standard however, changed the equation by delivering a higher degree of scalability, quality of service, and reliability.

In the United States, service providers are starting to recognize the benefits of delivering Metro Ethernet solutions. In some circumstances that demand extremely high performance, such as when video transmission is required, Metro Ethernet may be delivered in the form of Ethernet over SDH/SONET, or Ethernet over MPLS. Simple Ethernet alone is typically used for smaller Metro installations. The demand for fast and ubiquitous access to bandwidth-demanding applications and files like video, coupled with the demand for lower prices, has created an ideal environment for the commercial delivery of Metro Ethernet. Some carriers, faced with demand for Ethernet services, simply put an Ethernet interface on their SONET networks, and this worked to a degree, and gave Ethernet users the advantages of SONET’s Quality of Service and resiliency. However, the cost of such a solution is high, and some carriers are already starting to phase out SONET in favor of Metro Ethernet. Another supporting argument for carrier use of Metro Ethernet is that, because of the high bandwidth delivery capability, it can be used to deliver “triple play” services of cable television, telephone, and Internet, a package that has become increasingly popular. Nearly half of all carriers deploying Metro Ethernet are doing so to support the triple play offering.

There are many advantages. Besides its obvious high level of scalability, Metro Ethernet is multi-purpose, and can be used to deliver multiple types of data streams, including voice, data, and video. The capacity can be allocated in real time, so congestion can be easily bypassed; and further, the service can be managed on an individual customer-by-customer basis to meet the demands of each end user organization.

The last-mile connection however, will be the icing on the cake that delivers superior service to the desktop. While the Metro Ethernet network may transmit data effectively between major regions, how it is delivered on the “last mile” basis to the endpoints will also make a big difference as to how the final service feels to the user. As a practical matter, delivering the last mile in exceptionally large Metro Ethernet networks may require cooperation between multiple service providers. However, the last mile, regardless of which company implements it, is an easy connection, since Ethernet is most often used in corporate and residential networks.

Metro Ethernet, and its incorporation of carrier-class features, has dramatically changed the telecom industry and has allowed it to deliver more services to a wider area, and at a lower cost. The widespread demand for “triple play” offerings is a big driver for Metro Ethernet platforms. While Metro Ethernet’s popularity has increased, other options like ATM or private line services has decreased, due to the price comparison. Carrier-class Ethernet offers the same services as more expensive ATM services for example, at nearly half the cost. Many carriers deploying large-scale Metro Ethernet installations are using it not only for deployment of the triple play, but also for delivery of Ethernet virtual private LAN services, Ethernet private lines, and virtual private lines.

The technology has been proven, and Metro Ethernet offers the same advantages of performance and scalability as more costly solutions like ATM or SONET. Carriers, as well as end users, will enjoy reduced operating expenses as well as reduced capital expenditures by taking advantage of a Metro Ethernet service.

Ethernet has evolved beyond the simple, best-effort, lossy technology, to one capable of carrier-class provisioning and equal in quality and functionality to much more expensive options. Metro Ethernet now supports high-end functions such as high reliability, OAS support, and Quality of Service, making Ethernet the dominant technology of tomorrow.