As marketing luminaries have pointed out, "Ultimately, the provider's end game must be to deliver sustainable / reliable value to business customers beyond technology in a transparent network, providing a high level of customization... and compelling consolidation of vertical applications on a single or hybrid network".9 This seems to cement the role of Ethernet in the carrier network. However, gone are the halcyon days of build it and they will come, replaced by the need to economically justify incremental infrastructure builds. As many analysts have mentioned, ILEC providers like TELUS must carefully balance the existing investment in the legacy network with emerging technology investment. Through careful analysis of TELUS' existing network resources and newer carrier grade Ethernet transport equipment, TELUS has determined the best architecture for the deployment of metro Ethernet services is a hybrid, which is heavily dependant upon the available network resources and marketing forecasts. Specifically the following conclusions have been drawn: 1. For metro Gigabit Ethernet service, economics heavily point towards the implementation of a native Ethernet platform for aggregation and switching. Direct fibre connection between native Ethernet switches is the most economic alternative for short fibre cross sections, while the use of DWDM proves in for longer cross sections. 2. In terms of MDU access and the delivery of metro 10/100 Mb/s Ethernet, the use of native Ethernet switches is most economic if there are more than 3 services per location. Below 3 services, the legacy architecture (point-to-point FOIRLs) still proves in. There is also a case for the use of RPR or EoS technology in situations where SONET platforms already exist for TDM traffic requirements, and distance from customer premise to central office or POP is significant. 3. RPR continues to be evaluated as the draft matures towards ratification. The solution has proven in for rural backhaul of 10/100 Mb/s services, for high capacity access in rural (e.g. Oilfield applications) locations where fibre is sparse and existing latent capacity exists, and in situations where a SONET platform already exists and allocated or leased fibre costs are significant. 4. Where possible TELUS should continue to leverage latent network capacity and the legacy infrastructure to realize the most cost effective service. One architecture does not support all scenarios, and hence it is necessary to continually evaluate emerging architectures and technologies for delivering Ethernet service to customers.
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