A data view of the metro puts in perspective the different metro services and how they are offered by the different providers.
Figure 1-6 shows a view of the metro with the emphasis on the data access, data aggregation, and service delivery. As you can see, the metro is divided into three segments:
Metro access— This segment constitutes the last-mile portion, which is the part of the network that touches the end customer. For business applications, for example, access equipment resides in a closet in the basement of the enterprise or MTU.
Metro edge— This segment constitutes the first level of metro aggregation. The connections leaving the buildings are aggregated at this CO location into bigger pipes that in turn get ...