A modular, scalable DWDM system expands backbone bandwidth allowing Italian service provider FastWeb to offer high-speed Internet services
By Wilfried Schrupp, Account Manager Italy, South Africa and Switzerland, Siemens Information and Communication Networks
Dense Wavelength Division Multiplexing (DWDM) technology can push terabit-scale traffic through an optical fibre over hundreds or thousands of kilometres. However, in the rush to get a product to market, ultra-high-capacity DWDM equipment has not always been delivered as promised. Equipment that worked effectively in the laboratory has sometimes collapsed under the stress of live operations - and some carriers have been burnt as a result.
The Optical Networks Division of Siemens has delivered one of the first systems of this scale. The turnkey DWDM solution was deployed for FastWeb, the Italian provider of broadband telecommunications, Internet and media-related services. Currently in full operation, the system allows FastWeb to offer high-speed Internet service throughout Italy, thanks to a highly modular architecture that enables cost-effective, scalable growth.
The vision of FastWeb - a subsidiary of Milan-based network services provider e.Biscom which employs more than 1500 - is to provide a single network able to carry data, voice and video over IP, and to deploy this to business and residential customers in Italy and beyond. e.Biscom can then deliver a broad range of rich media services, from corporate video-conferencing and e-commerce transactions to consumer entertainment such as streaming video, TV on demand, and music files.
e.Biscom's high-speed Internet service operates at 10Mbit/s, allowing users to share all forms of content. Services are delivered throughout Italy by FastWeb. e.Biscom has also launched similar activities in Germany through acquisition of Hamburg-based broadband provider HanseNet.
FastWeb supplies residential users and business customers with Internet access at very high speed to support the latest bandwidth-intensive applications. To guarantee this speed to a growing number of users, transmission capacity at all network levels had to be dramatically increased.
Also, the ever-expanding range of services and applications required a solution that could be upgraded easily. Another key objective was cost management, which required an efficient transmission system and streamlined network administration.
To enable FastWeb to meet its future bandwidth needs Siemens delivered a complete DWDM system that provides virtually unlimited bandwidth in the backbone network while also bringing DWDM technology to regional and metropolitan networks.
Currently more than 2,000km of the network are in place between key Italian cities, and expansion is underway to cover the entire country, including Sicily.
The system went live - on schedule - in July 2001.
The solution features two products from the Siemens TransXpress DWDM product line: Infinity MTS 2.0 for the backbone network; and WaveLine for metro and regional networks.
The equipment also handles grooming and aggregation at all levels, from 64kbit/s for individual phone calls through to 2.5Gbit/s at the metro level and 10Gbit/s at the backbone. Siemens has also supplied a network management system that monitors all network elements and streamlines bandwidth provisioning.
As e.Biscom Chief Technology Officer Clint Cooper explains, "We have high bandwidth needs that can only be met by DWDM. We are partnering with Siemens because they can meet all our bandwidth needs through their TransXpress product line, both in the backbone portion of the network and the metropolitan distribution."
The MTS 2.0 backbone network deployed for FastWeb can transport data, video, and voice at up to 1.6Tbit/s using 160 channels at 10Gbit/s over a single fibre.
It can be upgraded to 3.2Tbit/s using 80 channels at 40Gbit/s. Highlights include flexible provisioning by remotely configurable optical add/drop multiplexers (OADMs) along with technology that greatly reduces costly optical termination and regeneration equipment. The system also includes advanced dispersion management, forward error correction, automatic gain tilt control and erbium-doped fibre amplifiers.
As well as high bandwidth, the MTS 2.0 network enables FastWeb to scale up to meet demand, minimising initial capital costs. Rather than deploying - and paying for - all 160 wavelengths at once, service providers can deploy optical filters in DWDM terminals in 20-wavelength increments.
The OADM granularity is two add/two drop channels on one card. This modular solution allows FastWeb to invest in capacity only when it's needed. Currently FastWeb can use 80 channels transporting 10Gbit/s each in its backbone.
In-service upgrades allow bandwidth to be extended without taking down the network, disconnecting phone calls, or disrupting other services. Upgrade modules are plug & play - remotely configurable by the network management software with a few mouse clicks.
In high-channel DWDM systems opto-electrical regeneration comprises the bulk of equipment cost. It is therefore imperative to reduce the number of electrical regeneration points to a minimum in order to avoid costly optical-electrical-optical (OEO) conversion.
The MTS 2.0 backbone provides better economy than DWDM solutions dependent on line regeneration equipment. EDFA-based optical line repeaters perform optical amplification on all DWDM channels simultaneously at much lower cost than OEO regeneration equipment, so the backbone network can span up to 1500km without electrical regeneration.
Raman pump amplification further reduces equipment costs by extending fibre reach before an optical line repeater is needed. The technique splices a laser pump directly into the fibre span, making the fibre the actual gain medium and effectively shortening the fibre span. Combined with EDFA technology, Raman amplification reduces the number of optical line repeaters needed, while maintaining signal quality.
The MTS2.0 backbone operates with remotely configurable OADMs that allow local traffic to be dropped and added without the need to terminate or regenerate express signals. Individual channels can be dropped to an OADM without disturbing the others. OADM sites are equipped with hardware to drop or add wavelengths by remote control, using tuneable transponders that can be adjusted to the actual dropped wavelength. These elements allow FastWeb to fulfil a customer request for bandwidth within hours, rather than days or weeks.
Also, using network management software for remote bandwidth provisioning, bandwidth can be deployed dynamically to meet changing traffic patterns and market conditions - if a customer in Reggio Emilia requests a 10Gbit line, a network administrator in Milan can provide it with a few mouse clicks.
The WaveLine DWDM transport product family, optimised for metro and regional networks, operates in ring or line topologies inter-operating with the MTS 2.0 DWDM backbone as well as local networks providing electrical SDH transport.
Like the MTS 2.0, WaveLine is designed for cost-effective managed transport of Gigabit services. It supports up to 32 DWDM channels, each with up to 2.5Gbit/s of bandwidth.
The modular design allows channel upgrades in convenient increments, as well as remotely configurable optical add-drop multiplexing for local traffic.
The third element of the FastWeb solution - the Telecommunications Network Management System - allows remote monitoring and configuration of all DWDM/SDH network elements (including third-party equipment). TNMS can manage the configuration of the entire network to handle end-to-end service provisioning and automatic routing. It can also monitor and manage each network element individually. For FastWeb, a single central administrator can efficiently manage the entire network.
Siemens also performed network planning using its automated TransPlan network design tool. TransPlan optimises the optical links, considering not only the physical location of possible regenerator sites but also all fibre parameters and limiting effects when light is pumped into optical fibres with high power. With a few mouse clicks, TransPlan generates a list of materials to create a technically sound and economical tailor-made solution. This is then transmitted to Siemens and the equipment dispatched, saving both time and costs by eliminating days of engineering work.
The FastWeb network is not the first large- scale Siemens DWDM project. In a joint initiative with WorldCom, Siemens set the world record for transmission capacity on a single fibre in an installed network (3.2Tbit/s) by deploying 80 wavelengths of 40Gbit per wavelength for a total capacity.
For rapidly growing carriers like as FastWeb, such advanced DWDM technology provides the foundation to support the latest bandwidth-intensive services that users demand.
"The ability to efficiently meet current and emerging bandwidth needs is essential in our business," concludes e.Biscom's Clint Cooper. "This technology allows us to deliver the superior service that we promise to corporate clients and consumers."
Regional Account Manager for Italy, South Africa and Switzerland