Survivability in a new pan-European carriers' carrier network based on WDMand SDH technology: Current implementation and future requirements

A pan-European carriers' carrier network, like other carrier networks, must cope with the enormous traffic inflation by introducing appropriate networ k solutions. WDM technology is the solution adopted by GTS Carrier Services ' Trans European Network unit (TEN, formerly known as Hermes Europe Railtel ), driven by bandwidth requirements, infrastructure limitations, flexibilit y, and cost. The introduction of such new technology presents specific tech nical issues, although it lays the foundation of future optical networking. Network outages are an important concern since, by using WDM, tens of giga bits of data are transported on each fiber. On one hand, traffic interrupti on is avoided as much as possible through secure fiber routings, cable prot ection, high design and equipment standards, and security. On the other han d, network protection techniques are used to limit the impact on services w hen inevitable outages occur. In this article we explain the role of the di fferent technologies in TEN's network. We concentrate on WDM and optical ne tworking where optical channels are used to interconnect the equipment used by the different technologies. We focus on optical network protection tech niques and illustrate that a clear requirement exists for this. We also emp hasize interworking issues that come into play when multiple technologies a re combined in the same network. It is not the intent to discuss only futur e requirements, but also to explain how the different aspects are currently implemented in TEN's operational network.