Abstract

A significant percentage of the overall data traffic supported by metro Ethernet networks is classified as ‘best effort’ traffic. Since the network does not guarantee zero packet loss for best effort data traffic, it can be over-subscribed. In other words, the Service Provider is permitted by its service level agreement with its customer to provision best effort traffic such that the aggregate bandwidth of the best effort traffic supported on a transmission channel is greater than the available bandwidth of that channel. Over-subscription of data traffic enables efficient utilization of transmission resources.

However, the architecture of today’s metro Ethernet networks does not enable the Service Provider to over-subscribe best effort data traffic, and realize the cost savings resulting from efficient transmission resource utilization. Essentially, a SONET channel is dedicated to each Ethernet service between the SONET transport network ingress and egress network elements, regardless of the classification of the data traffic (e.g., best effort or high priority).

This paper describes the results of an economic analysis that compares the capital and operational costs of today’s metro Ethernet network versus an alternative metro Ethernet network. The alternative metro Ethernet network incorporates Layer 2 switches at intermediate points in the network (i.e., between the customer’s premises or access point of presence and the metro core) that enable the over-subscription of best effort traffic within the metro Ethernet network.

This economic analysis shows that combined capital and operational cost savings of up to 60% can be achieved by deploying the alternative metro Ethernet network instead of today’s metro Ethernet network. The primary components of the capital cost savings associated with this analysis are stand-alone Ethernet switch, SONET add/drop multiplexer and digital system cross-connect panel elimination, and a reduction in the number of fibers and/or lambdas required to support the transport of data traffic in the metro core. The primary components of the operational cost savings are reductions in the time associated with completing service orders and resolving trouble tickets, monthly leased fiber facilities costs (CLEC/IXC only), the power consumed by transport and switching equipment, and the amount of physical space required to accommodate the transport and switching equipment. Additionally, Service Providers can realize revenue earlier, since the time interval between the receipt and completion of service orders is reduced.

In summary, by incorporating over-subscription at intermediate points in the network, Service Providers can realize significant capital and operational savings through efficient utilization of transmission resources.

© 2005 Optical Society of America