An upgrade route for core transport networks

In this paper we take a pragmatic view of the benefits of a transparent layer of optical cross-connects to supplement the SDH transport layer currently being deployed by all major telecommunications operators. We describe the findings of a cost study of future scenarios for the BT Core Transport Network under a range of different traffic carrying capabilities and technologies. The study shows that there is potential for all-optical transport technology to be cost effective particularly if very high blocks of traffic are to be routed. For 20 times current traffic levels (expected soon after the year 2000 with the take up of broadband services) use of an optical layer is predicted to give capital cost saving of up to 50%. We also explore the benefits of deploying an optical layer for resilience to cable breaks, an issue of growing importance to network operators.