Survivability in a new pan-European carriers' carrier network based on WDM and 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 network 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, flexibility, and cost. The introduction of such new technology presents specific technical issues, although it lays the foundation of future optical networking. Network outages are an important concern since, by using WDM, tens of gigabits of data are transported on each fiber. On one hand, traffic interruption is avoided as much as possible through secure fiber routings, cable protection, high design and equipment standards, and security. On the other hand, network protection techniques are used to limit the impact on services when inevitable outages occur. We explain the role of the different technologies in TEN's network. We concentrate on WDM and optical networking where optical channels are used to interconnect the equipment used by the different technologies. We focus on optical network protection techniques and illustrate that a clear requirement exists for this. We also emphasize interworking issues that come into play when multiple technologies are combined in the same network. It is not the intent to discuss only future requirements, but also to explain how the different aspects are currently implemented in TEN's operational network.