ce, resiliency, and manageability. This has resulted in a number of evolutionary changes to Ethernet technology, and we will describe how some of these requirements are being addressed. Nevertheless, it is acknowledged that such solutions will have to compete in the marketplace with the other technologies that can provide the infra- structure to deliver Ethernet services. Chapter 14 Next Generation Ethernet What Is Carrier-Grade Ethernet? Those working on Ethernet will find themselves frequently hearing the term "carrier-grade Ethernet." But what does it mean? The reality is that there are many definitions of "carrier- grade," and it can often be assumed that it is whatever the speaker wants it to mean. In some cases it might mean specific technological solutions for the delivery of Ethernet ser- vices over a WAN technology such as SDH/SONET or MPLS and how these are constructed to deliver a solution, or it might mean implementations based purely on Ethernet technol- ogy, a combination of the two, or simply a service that meets a service level agreement that is more than just best effort. The view offered here of what constitutes a carrier-grade, or indeed carrier-class, solution is any solution that delivers providers with a set of features that allow the service provider/network provider to offer services that can meet defined performance criteria in the form of a service level agreement and provide operational capabilities to manage both the service and the network. There is a big step change in the requirements from those needed in many enterprise networks to those required in the wide area network. Some of the requirements that often appear in the network provider space include, but are not limited to A decoupling of the description of a service from any underlying technology. The service provider wants to avoid the close coupling of service features to a particular technology because this makes any form of future technology migration while retaining that service a very difficult proposition. Operational sup