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Cross Border Dark Fibre triangle for multiple 10 gigabit connection of Austrian, Czech and Slovak research and education networks enabled by advanced photonic technology

CESNET association has increased the capacity of the interconnection between CESNET2, the Czech national research and education network, and the partnering Austrian academic network ACOnet, by upgrading the existing capacity from shared connection via SANET (Bratislava) to a dedicated 10 Gb/s channel. This means that ACOnet, CESNET2 and SANET are connected together via a cross-border dark fibre triangle.

The optical line from Brno to Vienna, which is approximately 224 km long, has been equipped with CLA PB02 optical amplifiers that have been developed as a part of optical research activities of the association. Chromatic dispersion of G.652 optical fibre has been compensated by new compensating elements – Fibre Bragg Gratings (FBG). FBGs were successfully deployed and tested for the first time on the CESNET2 line Brno–Bratislava in February 2006. The design of this line has been done for capacity up to 8×10 Gb/s and fixed DWDM (Dense Wavelength Division Multiplexing) multiplexers and demultiplexers are used. Terminal routers are equipped with Xenpak DWDM pluggable optical transceivers. IP traffic statistics are available on

All devices have been installed only at the end points of the line in Brno and Vienna and no in-line elements have been deployed – the Nothing In Line (NIL) method has been used again and as far as we know, 8×10 Gb/s over 224 km of dark fibre is the longest NIL distance that has been reported for any production network. The main advantage of the NIL solution is represented by lower deployment and operational costs and increased reliability. Via this method, networking and photonics research facilitates international collaboration of researchers in different research areas.

In comparison with point to point Cross Border Fibre connection, in the case of fibre failure, triangle connection allows redirection of traffic in times less than 60 ms, so overall reliability of end to end connections is improved significantly. This is achieved by Layer-2 protocols (802.1q and 802.1w), avoiding a slower and more complicated solution on the IP level. 10 GE VLANs are implemented on this background, giving the impression that distances between countries have disappeared.

ACOnet ( is a network for science, research and education in Austria,  operated by the University of Vienna. ACOnet provides a powerful and resilient backbone network infrastructure, mainly based on Gigabit and 10 Gigabit Ethernet technology, with its major points of presence co-located at Universities in Graz, Innsbruck, Klagenfurt, Linz, Salzburg and Vienna. ACOnet supplies its customers with multi-gigabit Internet access with a special focus on good national and regional connectivity through public and private peerings and excellent connectivity to the European and global research community via GEANT2.

CESNET association was founded by universities and the Academy of Sciences of the Czech Republic. It is currently financed primarily by its members and the Research and Development Council. The association operates and develops CESNET2, the national gigabit optical network intended for research and education, and participates in research and development of information and communication technologies. Thanks to its research activities and achieved results, CESNET association represents the Czech Republic in European GN2 project, as well as in other international projects. Among other countries, the association currently cooperates with Canada, the Netherlands, and the USA on the construction of GLIF (Global Lambda Integrated Facility), a global lambda network whose Czech section is called CzechLight.

SANET association, established in 1991 by Slovak universities, schools and the Slovak Academy of Science as a non-profit organization operates dark fibre infrastucture consisting of leased fibres in the national backbone and owned fibres in the metropolitan area networks. On top of this infrastructure SANET provides multigigabit IP and layer-2 services for academic, research and educational organizations in Slovakia. Since 2002, the association is actively promoting cross-border dark fibre connections with neighbouring countries. SANET represents Slovak Republic in TERENA and CEENet organizations. More information about SANET can be found at

SANET, Vazovova 5, 811 07 Bratislava, Slovakia, tel/fax: +421-2-52498094,