Basic DWDM Ring Commissioned on the CESNET2 Network

The CESNET association completed construction of a DWDM (Dense Wavelength Division Multiplexing) optical transmission system in the ring topology Prague–Brno–Olomouc–Hradec Kralove–Prague within the national research and education network CESNET2 at the end of 2005. The system utilises 32-channel ROADM (Reconfigurable Add/Drop Multiplexer) at all access points, based on PLC (Powerline Communication) technology often employed in optical switches. The software-reconfigurable ROADM enables flexible establishment of optical transmission channels over a DWDM network as well as their branching off or insertion at required network nodes, thus providing bandwidth on-demand facilitating increasingly frequent unforeseen data transfers and the related bandwidth requests. The DWDM system itself is designed and constructed in order to provide up to 32 10 Gbps channels as well as to enable transparent transmission of an independent "coloured signal", i.e. a signal created outside the DWDM system).

Completion of the basic DWDM ring also enabled an upgrade of the IP/MPLS (Multi Protocol Label Switching) layer of the network to 10 Gbps on the lines between Prague and Hradec Kralove, Hradec Kralove and Olomouc, and Olomouc and Brno.

The DWDM technology and implementation of ROADM represents a significant shift in the development of the optical network towards provision of bandwidth on-demand and creation of a logically independent networks on common optical fibre infrastructure. The added benefit is the capability to satisfy demanding and potentially aggressive applications with specific requests on dynamic response of the network (e.g. low latency) and bandwidth – such as Grids – without affecting services provided to traditional applications.

The optical layer enables upgrading of transmission capacity to 10 Gbps as well as provision of lambda services for research projects and connected users on a national and international scale. The implemented DWDM technology produced by Cisco Systems and supplied by Intercom Systems, a. s., enables operation of several optical channels on a single leased optical fibre. In subsequent stages, the technology will offer integration to the existing IP network and transition to the IP-optical backbone, including implementation of optical switches for dynamic switching of optical paths.

The first optical line providing the bandwidth of 10 Gbps utilising the DWDM technology was commissioned by CESNET at the end of 2004 between Prague and Brno.

The CESNET association was founded by Czech universities and the Czech Academy of Sciences. It is currently financed primarily from the budget of the governmental Council for Research and Development, and member contributions. The association conducts research and development in the area of information and communication technologies, builds and develops the national gigabit optical network CESNET2 dedicated to science, development and education. Thanks to the its research activities and the results achieved, CESNET acts as a representative of the Czech Republic within the development project of the pan-European network GEANT2 and actively partakes in its implementation. Besides other activities, the association partakes in the Global Lambda Integrated Facility (GLIF) project.