Introduction

Present Ethernet deployments on the LAN side are mature, very well understood, fairly inexpensive, and serve the requirements well. In the last decade, Ethernet technology has evolved from the 10 Mb/s shared wire model to switched operation over unshielded twisted pair (UTP) that support 1000 Mb/s and then on to fiber optic transmission from 100 Mb/s to 10 Gb/s rates with transmission distances spanning from 2 to 2000 km using long-haul dense wavelength-division multiplexing (DWDM) systems [1]. Newer Ethernet versions also support up to eight classes of service and unicast/multicast/broadcast modes via the VLAN technique. This evolution makes it a good candidate for both LAN and WAN interconnection space. Recent projections estimate that close to US$29 billion will be spent worldwide on Ethernet in metropolitan networks between 2004 and 2008 [2]. But Ethernet technology lacks carrier-grade features such as QoS, provisioning, fault tolerance, TDM compatibility, OAM, and self-healing, making it unsuitable for backbone and carrier space. Recently there has been a lot of standards activity at the Metro Ethernet Forum (MEF), the Internet Engineering Task Force (IETF), and the International Telecommunication Union (ITU) with regard to addressing these requirements, thus paving the way for wider deployment of Ethernet as a carri-er-class interconnection fabric [3]–[5]. Early deployments are on in the Asia-Pacific region.