A CARRIER'S PERSPECTIVE ON IMPLEMENTING NEW DATA PROTOCOLS OVER LEGACY NETWORKS

摘要

In the coming years, there will be a high demand for data-oriented client services. Much of this demand will be due to the popularity of Ethernet, which is continually becoming more functional and less expensive. All service providers, including legacy inter-exchange carriers (IXC), are hoping to profit from this trend. However, despite the expected increase in demand, it is difficult for a legacy IXC to capitalize on this market because the revenue per bit from data traffic has generally been low. Thus, a legacy IXC must have an efficient, cost-effective method of transporting data through the network that requires little in the way of upgrades or new equipment deployments. The industry has responded to this challenge by developing a set of protocols enabling SONET/SDH networks to carry data traffic more efficiently. The set of protocols includes Generic Framing Procedure (GFP), Virtual Concatenation (VCat), and Link Capacity Adjustment Scheme (LCAS). Together, the protocols are commonly referred to today as next generation SONET/SDH, because the protocols work with SONET/SDH to help it to more efficiently transport data. The International Telecommunications Union (ITU) has recently standardized the protocols, a step that should enable some degree of interoperability. Currently, some system vendors and many chip vendors are offering products that support at least some of the features of GFP and VCat. In this paper we show how a legacy IXC can use next generation SONET/SDH protocols to decrease the cost of transporting data traffic through the SONET/SDH network. The paper also discusses several important next generation SONET/SDH implementation issues, including deployment strategies, trade-offs of granularity in VCat, service multiplexing, and operations management. All of the issues are discussed from the point of view of a legacy carrier attempting to reverse the trend of the difficulties related to generating profits from data services.