3   Optical Networks

3.1   Objective of the activity

In 2004, the Optical Networks activity was focused mainly on the CEF (Customer Empowered Fibre) network research and development and on cooperation on the global experimental lambda infrastructure GLIF (Global Lambda Integrated Facility) research and development. Within this activity, we were dealing with:

We paid special attention to low-cost technologically advanced facilities which should enable extending the CEF networks, increasing the number of endpoint workplaces and their gradual deployment in developing countries.

Within the scope of the activity, the CESNET Association became a research workplace which also supports development of foreign CEF networks. Supporting the CESNET2 CEF network had become commonplace in the Optical Networks activity. Making GLIF accessible for all those workplaces in the Czech Republic that are able to participate in relevant international application projects and experiments, as well as its use as a national testbed for further international research cooperation (e.g., in the GN2 JRA4 where a new international fibre and lambda testbed is being built), are the long-term goals of the CzechLight network realisation.

The research results are being verified and used both in laboratory environment and in wide-area experimental networks, and later also in production networks (e.g., CESNET2, AMREJ, and GN2). In some cases we found out an advantage of passing from a common commercial relationship with fibre lessors (when one must be able to specify one's requirements of fibre lease and to acquire offers at acceptable prices) to a collaboration in the research and development field, which allows acquisition of optical lines of hyper-standard quality, frequent experiments on the line setup (e.g., changes of length and parameters of test lines, changes of the G.652 and G.655 fibre length ratio), testing an equipment developed for in-line use, etc.

The research team collaborates on the verification with network designers and operators in various countries, with widely varied conditions. The activity involves the participation in the EU project GN2 - Multi-Gigabit European Academic Network (the SA1, JRA3, and JRA4 activities) and in one grant project. Making ready for participation in the EU SEEFIRE project, the CzechLight Extension international project (R&D collaboration with a hardware supplier) and participation in another grant project is another result of the 2004 work.

The GN2-SA1 Procurement activity brings new routes and technologies for the GÉANT2 pan-European production network. The GN2-JRA3 activity researches the current state and further development of the Bandwidth Allocation and Reservation Service (in other words: "Bandwidth on Demand", BoD) in its connection-oriented end-to-end version.

The GN2-JRA4 research activity gathers knowledge about new network-building concepts and about interconnection of European national test networks, as well as testing new transmission technologies.

A goal of the EU SEEFIRE project is a study of network infrastructure availability and possible strategies in regional NREN development in south-eastern Europe. It should help involve those countries in the eInfrastructure community and increase their technological competence to cooperating internationally. The technical core of the work is the preparation of long-distance and international dark fibre connections and selecting low-cost advanced technology for lighting them.

The CzechLight Extension international project prepares the extension of the CzechLight experimental network both in the geographical and functional senses. Transmission and switching Cisco equipment for CEF networks will be developed and verified with the manufacturer's support and their applications will be tested within the project.

A grant of the Grant Agency of the Czech Republic, started in 2004, is focused on Optimizing the data transmission at 10 Gbps over G.652 fibres with respect to maximum transmission distance without deploying in-line EDFAs. A newly acquired grant of the Information Society programme targets the TDM-pumped Raman fibre amplifiers.

3.2   Supporting the CEF network development

In 2004, the Optical Networks activity started supporting development of foreign CEF networks. This support is usually based on the principle of mutual advantage. The EU (SEEFIRE project) supports us to faster deploy the project results in south-eastern Europe in 2005. This activity has also selected the program of the CEF Networks seminar attended by many international participants and has established the international mailing list for its participants. Besides, collaboration of the activity research team on acquiring fibres and verifying transmission systems for the CESNET2 network has become commonplace.

Independently, the leader of this activity was asked in January 2004 to give an overview lecture on deploying dark fibres in European NRENs at the TERENA Networking Conference 2004; he also became a member of the GN2 Procurement committee project. Within the frame of the GN2 preparation, the activity research team won the leadership of the Technology testing task in JRA4 and became an important part of JRA3.

At the Customer Empowered Fibre networks seminar which took place in Prague on 25th and 26th May 2004, 46 participants from 20 European NRENs, Canada and the USA took part. 17 lectures were presented about the CEF network deployment in the participants' countries and about the most important trends in this area. It has been found out that the results and concepts of the Optical Networks activity project team belong to the most advanced all over the world in the relative fibre deployment scope and in the use of advanced transmission equipment. A large number of participants appreciated the organisation of the seminar and they expect us to continue.

The CEF networks are characterised by the fact that it is their users themselves who operate them. These users only rent a fibre (alternatively, they have it laid) and they themselves acquire the hardware which transmits data over the fibre. Thus, they have the fibres - or a right to use them - and at the same time, they choose the way of building the network (especially its optical transmission system) and network management. As the users of customer empowered networks, often an R&D workplace staff, have specific requirements of transmission parameters and prices, the CEF networks are "tailor-made" according to the actual user needs.

The seminar participants came to the conclusion that the CEF networks are now successfully implemented in several countries, including the Czech Republic, within the NRENs. They also recommended further international cooperation which would mainly focus on continual exchange of the following information on the CEF networks in near future:

At the seminar, a discussion took place about the feasibility of building the GN2 pan-European production network as a CEF network, which has turned out to be very important for further development of the GN2.

Currently, CESNET is probably the most important organization worldwide in the sphere of long-span CEF optical network design and operation. This is the result of some four-year development supported also by the former and current research plan, by universities, the Academy of Sciences and by almost all of the dark fibre owners in the Czech Republic.

As one of the first organizations, CESNET took over the development of CEF networks rather early - at a time when this trend was hardly supported by anyone; in 1999, CESNET prepared a 323 km, 2.5 Gbps route Prague-Brno using leased optical fibres and started its operation in February 2000. As a result, gigabit transmission lines of the CESNET2 production network consisted not only of leased dark fibres terminated with transmission equipment maintained by the CESNET staff, but also of leased gigabit transmission services maintained by telecommunication operators. It was found out that leasing the dark fibres should be strongly preferred for cost reasons. Moreover, using one's own transmission equipment brings about very important advantages concerning the future network design and management. These networks offer not only the "best effort" services but also those needed for real-time applications (connection of distant expensive or unique research equipment, remote presence, remote collaborative environment, etc.).

Since 2002, intensive efforts have been made to convert the Czech Republic CESNET2 NREN to dark fibres. In contrast to other contemporary CEF networks worldwide, we opted to significantly decrease the number of regenerators and amplifiers which are connected to dark fibres in the field in so-called huts. As a result, instead of commonly used fibre lines with spans between huts of some 80 km, very long fibre segments of 150-200 km or single-span lines of about 300 km are deployed. This hut-skipping technology reduces the operational costs and is very important if lack of highly-qualified optical staff prevails. Consequently, the architecture of NRENs (placing the points of presence within university premises) as well as of other CEF networks can be adapted to minimise the number of huts used.

In 2003, CESNET started to cooperate with the supplier to build optical fibre first-mile lines. The conversion of the CESNET2 production network to customer empowered dark fibres was mostly finished in 2003.

By December 2004, CESNET was using 3,828 km of dark fibres, including 3,310 km within the CESNET2 production network; no domestic gigabit service from telecommunication operators has been rented. Most of these fibres are lighted as long-reach circuits. CESNET operates six single-fibre long-distance lines (over 350 km in total) at transmission speed of 100 Mbps, suitable especially for connecting smaller network nodes. International 1GE dark fibre line Brno-Bratislava for the Slovak NREN SANET connection and 1GE dark fibre line Ostrava-Bielsko-Biala for the Polish NREN Pionier connection are operational.

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Figure 3.1: Topology of the CEF CESNET2 network as of December 2004 (large image)

3.3   Supporting the experimental network access and use

GLIF is one of the most important global activities within the networking research and development. Participation in it is essential for the position of the Czech research in the world (50 most important world professionals chosen by the founding organisations participated in GLIF research negotiations). Correspondingly to the GÉANT2 hybrid network and GN2 testbed construction and in harmony with GLIF strategy we suppose that GLIF will not compete with any kind of service offered by these networks but it will investigate more advanced applications and global experiments.

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Figure 3.2: Global Lambda Integrated Facility (large image)

The Prague-Amsterdam GLIF lambda connection over the Dutch NetherLight experimental network was at 2.5 Gbps speed since 2003. The access was upgraded to 10 Gbps on 1st September 2004 - at a time when NetherLight changed from Cisco switches to Nortel switches. Despite this change, the connection worked well. The position of CzechLight within the GLIF network (and consequently within an American TransLight node) thus reached an adequate level; the possibilities of international experiments widened and the interest for the cooperation with the Czech Republic abroad increased. The results were presented at the world GLIF meeting in Nottingham in September 2004.

The CzechLight network is used for GLIF access and as a testbed for further tests and for accessing other networks (e.g., the GN2 testbed). The use of CzechLight therefore is and will be of the same character as the use of GLIF and testbeds: enabling the experimental development of networking and development of new and more advanced applications in the way which is unacceptable for production networks or at a time when it is not yet possible with production networks.

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Figure 3.3: CzechLight network (large image)

For the users from various branches of research, the CzechLight experimental network makes possible qualitatively new solutions of their requirements and needs which emerge during scientific and research cooperation. In the Institute of Physics of the Academy of Sciences of the Czech republic (FZÚ) in Prague 8 (Na Slovance 2), the Regional Computing Centre for Particle Physics was established. The Centre was opened on 1st November 2004. It provides computational and storage capacity for demanding calculations for the D0 experiment on TEVATRON accelerator in FERMILAB and for the ATLAS and ALICE experiments on LHC accelerator at CERN which is under construction. Among the cooperating workplaces in Prague are the Faculty of Mathematics and Physics of Charles University (MFF), the Faculty of Nuclear and Physical Engineering of the Czech Technical University Bøehová 7 and Trojanova 13 (FJFI), the Institute of Technical and Experimental Physics of the Czech Technical University (ÚTEF) and the Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, Øe¾ (ÚJF). Realization of the CzechLight access for these institutes is under way. So far, we have connected three of them by means of dedicated dark fibres (ÚJF, MFF, FZÚ). The connection tests have been successfully carried out at all the institutes. In collaboration with the CWDM project of the CESNET Development Fund, the GE lambda connection over PASNET for FJFI Bøehová is already prepared using the FWDM mux/demux technology for 1310 and 1550 nm wavelengths. By the end of 2004, after the rest of technical transmission equipment is delivered, the interconnection of the workplaces will be tested as one unit. The ÚTEF and FJFI Trojanova will be connected in the beginning of 2005. Next important step from the viewpoint of application development is to set up another optical connection from the above-mentioned institutes to other important international centres - e.g., RAL in England, FNAL in the USA, TAIPEI in Taiwan, etc.

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Figure 3.4: Current connection of particle physics workplaces to CzechLight (large image)

The particle physics applications belong to those in the world which initiated the creation of lambda networks and hybrid networks and they are also one of the first to use the CzechLight. Of course, the intention of CzechLight use is much broader. Within the Optical networks activity, we now offer collaboration on the CzechLight connection to groups from various fields when they are preparing applications needing the GLIF. During the realization, direct participation of the application researchers in the Optical networks activity or collaboration with another activity or another project organised by CESNET - according to the situation - is essential. Several first applications are thus of pilot character and they will be used as an example for other applications.

An application or its part may later move to the production network if it is necessary (e.g., because high availability is required) and feasible. Having the first mile solution - e.g., connecting the workplace over optical fibres which are now realized for the CzechLight connection - will be necessary even at a time when deploying the international and national transmissions at 10 Gbps and more over hybrid production networks providing lambda services is possible.

The accessibility of GLIF and CzechLight for applications depends on manual planning and resource allocation now. Although the resource allocation (mainly of transmission capacities) will later become programmable and therefore also faster, it will be generally considered as a time-limited allocation. But at the first stage of development, it is usually more than sufficient.

In 2005, the work on making the CzechLight accessible in the Czech Republic will continue for experiments on computer networks (such as international transmissions for the 6NET project), for experimental data transfers in the field of particle physics, for interconnecting the super-computer clusters, for remotely operated experiments and measurements and for accessing costly equipment (first tests on accessing the Spirent AX/4000 generator/analyzer with 10GE ports have been carried out), for medical projects and other applications. The aim is to connect all research workplaces capable of testing the use of lambda services for their international collaboration but unable to do this without the CzechLight. It will also be used for national GN2 testbed expansion within the GN2 JRA4 framework.

To make the CzechLight connectivity accessible in Moravia, its Brno node will be complemented by a 10GE switch. Its connection to the Prague node still has several variants: the suppliers of Prague-Brno fibre line will either manage to lower the attenuation to the 65 dB they promised, or the transmission error rate will be lowered by our using more sensitive receivers and filters, or we will use one in-line optical amplifier in each direction. Other workplaces in Bohemia will be connected with GE or 10GE using fibres from Prague (fibres to Plzeò have already been prepared). Moravian workplaces will use fibres from Brno.

3.4   Methods of data transmission over CEF networks

We focused on 1 Gbps (1GE) and 10 Gbps (10GE, SONET/SDH) NIL transmission testing in particular. Using CWDM GBIC, we successfully transmitted two 1GE channels over 325 km with sufficient margins. During these experiments we used an EDFA booster, Raman fibre amplifier and optical tunable filter for channel separation and noise suppression.

We extended the 10 Gbps experiments by testing 10 Gbps DWDM SONET Cisco ONS 15454 equipment. Transmission over a 290 km G.652 fibre is an important result of this testing. In this configuration, we used the following equipment: EDFA booster, Raman laser, two EDFA preamplifiers, four optical filters, and four DCF modules altogether.

Further tests were performed on G.655 fibres which we acquired in May 2004. With these fibres, the maximum distance was 290 km as well. In contrast to the G.652 link, using only one EDFA preamplifier, three filters and one DCF module was sufficient. Last group of tests was performed on a combination of G.652/G.655 fibres which has a considerable practical importance. Some lines for both CESNET2 and CzechLight networks are composed of these fibres. The most important result is an error-free 302 km/65 dB transmission where 10G DWDM SONET line cards were deployed and the line was composed of a 50 km G.652 and a 252 km G.655 section. The maximum distance when the ONS 15454 system was still operating was 313.4 km/67 dB but in this case, the bit error rate was too high and unacceptable for practical deployment. One of the most important findings from our testing the G.652 and G.655 fibres is as follows: the best properties of any line with regard to maximum transmission distance were reached when both ends contained at least a 15 km G.652 fibre section. The reason is a larger effective cross section and the resulting possibility of launching higher optical power. On the other hand, the G.655 fibre is preferable due to smaller chromatic dispersion. All these results were utilized for design and deployment of a 10G CzechLight line from Praha to Brno.

International cooperation started especially with colleagues from the Irish and Slovenian NRENs who expressed a serious interest in deploying optical amplifiers which are being developed in CESNET, and in deploying 10 Gbps NIL transmission.

We also continued our experiments in 10GE signal transmissions (Cisco Catalyst 6503) and we were able to overcome a line length of 287 km (the line consisted of 202 km G.655 and 85 km G.652 sections). We have also successfully tested the transmission of 2×10GE on this line where the maximum distance, when composed exclusively from the G.652 fibre, was limited to 252 km. A significant improvement is expected from deploying the DWDM XENPAKs where the receiver sensitivity is higher than that of 10G DWDM SONET/SDH line cards.

Figure demonstrates the possibility of covering the Czech Republic territory using the Cisco ONS 15454 system and NIL method. It is obvious that the most important line Praha-Brno remains the biggest problem.

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Figure 3.5: Coverage of the Czech Republic using Cisco ONS 15454 in NIL deployment

We were able to start the experiments in the 1310 nm band amplification thanks to the loan of praseodymium amplifier (PDFA) from FiberLabs and later purchase of two samples. Exploiting a very low chromatic dispersion of G.652 fibres in this band, especially for bit rates of 10 Gbps (and higher in the future), will bring advantages. With NIL concept in mind, we extended the transmission distance for 10GE XENPAK modules from 40 km up to 120 km, for 1GE LXE GBIC transceivers from guaranteed 30 km up to 125 km. With one inline amplifier, the maximum transmission distance increased up to 160 km, or 175 km. In addition to PDFA, we have also tested other amplification techniques in the 1310 nm band. We used a Raman fibre laser to counter-directionally pump the transmission fibre to obtain the distributed Raman fibre amplifier. Deployment of Raman amplification in the 1310 nm band is relatively new, we found only one vendor of this technology. It is important to keep in mind that the attenuation of a 160 km G.652 fibre is approximately 60 dB. We have plans to test 1GE with DFB lasers (longer transmission distances are expected) and above all other 10GE adapters (S2io, Chelsio) which are available with 1310 nm transceivers only. One Czech operator has shown particular interest in these results.

We investigated, both theoretically and experimentally, the possibility of stabilizing the gain in a cascade of three Raman fibre amplifiers. We have been using an eight-channel DWDM test system purchased from grant resources of the GA ÈR project. Simultaneously, we started theoretical analysis and experimental verification of broadband time-division multiplex pumped Raman fibre amplifiers optical characteristics. The ÚRE AV ÈR institute in cooperation with CESNET succeeded in obtaining a project within the framework of Information Society programme. Results of these projects will be used in future building of fibre networks and, possibly, also in the GÉANT2 and SEEFIRE international projects.

We applied the acquired theoretical and practical experience particularly to the extension of the CzechLight network. The point of presence in Brno was established in planned configuration with its 10 Gbps connection to the point of presence in Prague and realised as NIL but the actual error rate of this link is intolerably high. The main reason is the high attenuation of the line. The attenuation promised by the fibre provider for this line of 298 km composed of G.652+G.655 was 65 dB. At the time of handover, the attenuation of the line was 74 dB and after several adjustments by the lessor, current attenuation is about 67 dB. A laboratory line with the attenuation of 65 dB (302 km fibres on spools) used for data transmissions at 10 Gbps worked error-free. The lessor promised to further reduce the attenuation of the line and another improvement can be done on our side, too (tunable fibre gratings for compensating the chromatic dispersion, low-noise amplifiers based on the PC Light, improved optical filters for noise suppression).

The results of our research in this area were published at international conferences and in prestigious journals. A full list can be found in the Annex of this publication.

3.5   Transmission equipment for CEF networks

Within the PCLight activity, a prototype of fully remote-controlled optical fibre amplifier PCLight 2in1 was constructed as a part of PC-based network equipment called PC Light.

The core of PCLight 2in1 equipment is an EDFA module containing two amplifiers. The first is designed as a booster amplifier and the second as a pre-amplifier with a very low noise figure. Thanks to this construction, one can use the PCLight 2in1 amplifier on lines where optical amplification of the signal behind the transmitter and in front of the receiver is necessary, and this is possible both on single-end amplified shorter lines as well as on longer lines, including those with chromatic dispersion compensation. During the laboratory experiments with this amplifier, overcoming a distance of 225 km of G.652 fibre using just a booster at 1GE signal transmission, and distance of 300 km using both the booster and pre-amplifier was possible. At coincident fibre pumping by a Raman laser, the reachable distance has increased to 325 km. The PCLight 2in1 amplifier was successfully deployed in testing operation on a CzechLight 1GE experimental line Prague-Plzeò (length 159.4 km, attenuation 36.7 dB). It was also tested on a CESNET2 production network line Prague-Hradec Králové (150.4 km, attenuation 35.69 dB) which is being prepared.

Positive response not only from inside the CESNET organization led us to develop a new version which will use two EDFA modules in one case of 1U height. It will provide significantly higher reliability parameters thanks to a backup power supply, GSM modem for out-of-band management and important operational parameter monitoring (optical power outputs, power supply voltages, amplifier and power supply temperatures, fan rotational speed). The prototype is nearly finished, we are only waiting for replacement of supplied defective power sources.

Two types of PC 1GE LAN adapters for PCI-X bus have been developed for simple and economical connection to experimental networks (e.g., the CzechLight). The first type uses standard two-fibre CWDM transceivers. In laboratory environment, a maximum reachable distance of 125 km over G.652 fibre at transmission speed of 956 Mbps was achieved. This transmission speed corresponds to maximum achievable speed of a direct PC to PC connection with attenuators. We expect that the reachable distance should reach up to 140 km when newer transceivers, which have lately appeared on the market, are used. The second type of GE adapters is designated for economically effective full-duplex optical transmission over a single fibre. The first direction uses 1510 nm wavelength, the second direction uses 1590 nm. The span reached in laboratory was 105 km of G.652 fibre at a maximum transmission speed of 956 Mbps.

The interest in PC Light shows that the current component basis for optical transmission systems allows constructing significantly better/cheaper transmission equipment than that offered on the market. That in itself would not be a sufficient reason for building such devices within the Optical networks activity, but even more important is the opportunity to use these and similar devices for verifying the principles of building optical and opto-electronical networks. In 2005, we intend to extend the current optical workplace to a laboratory testbed (with remote lambda access later on). This laboratory testbed will be designated to research, develop and verify new optical networking facilities. This way, we expect to influence the research, development and deployment of CEF networks towards lower prices, higher technological level and higher transmission speed (40 Gbps and more). Optical switches will also be one of the construction elements tested in 2005. In contrast to Calient switches tested in Starlight and NetherLight, we wish to aim at using planar-based components. The possibility of easy integration and higher mechanical resistance of planar switches is very beneficial.

3.6   Free Space Optical Transmissions at 100 Mbps and more

While building the CEF networks, we may find that laying fibres in some locations may be difficult or expensive although the span may be rather short (e.g., hundreds of metres). This is typical mainly for the connection of end users (so-called "first" or "last" mile). In such cases, a link based on the WiFi wireless technology (802.11b or 802.11g) is usually chosen but this choice offers a maximum transmission speed of 6 Mbps or 20 Mbps, respectively, and it has frequent interference problems. However, CEF networks usually need 100 Mbps to 10 Gbps transmission speeds for their first mile. Optical transmission sets at 2.5 Gbps are already available from suppliers and there are promises of 1 Gbps microwave transmission sets. But broad application in CEF networks (they will become "CE networks" then) will also depend on low production and operational costs, and for the purpose of experimental networks building, the possibility of modifying and developing appropriate hardware is also necessary.

The development follows up with the considerable experience of the CZFree network with development and deployment of low-cost 10 Mbps FSO (Free Space Optics) facility which enabled many university and secondary school students and other applicants including teachers to obtain connection at 10 Mbps from their homes, which would be too expensive if bought as a commercial service. It is very important that thanks to this, high-speed Internet access has been spreading fast which would not be possible in a common commercial way. We are therefore searching for real possibilities of using low-cost facilities for CE network building, where also higher transmission speeds will be necessary, and we are comparing them to commercial offers of corresponding devices.

In a Beroun locality, long-term testing of an operating 10 Mbps FSO connection to the CESNET2 network and its mechanical construction had been performed. After evaluating the results, we made some changes in the mechanical construction and we upgraded the FSO. We also attempted to use 100 Mbps electronics but the sunshine suppression necessary for APD photodiode in the receiver was not sufficient.

We developed a new mechanical construction for FSO electronics which can operate at higher transmission speeds (100 Mbps and more). We presented the aspects connected with the development of the 100 Mbps FSO electronics and mechanical constructions at the Optical Communications 2004 conference. At the same time, a professional article dealing with the criteria for FSO evaluation and possible solutions to construction problems was published in the Proceedings volume. Before the end of the year, we tested basic functional electronics samples at 100 Mbps with an APD photodiode and VCSEL laser on a 250 m long route. The tested route was equipped with low-pass optical filter which cuts off the wavelengths from 790 nm upwards. Moreover, we will use an interference filter which should limit the interference outside received wavelength window of 30 nm. We have upgraded the current 10 Mbps FSO and prepared it for possible use of 10 Mbps and 100 Mbps electronics, respectively. This equipment will be used for accessing the CzechLight from some of the workplaces. It is a low-cost facility (roughly 2,000 Euro) which will allow another community of applicants to access the GLIF and high-speed networks.

For better comparison, we use technical and pricing information of commercially offered devices. Carrying out user tests or deploying such equipment is even more important. In 2004, we had a very good experience with a Laserbit laser system installed between the University of West Bohemia campus and the Borská Student Hostel. The system operates as so-called media convertor. It is modular and an appropriate module is always selected for the installation, according to transmission line length and required speed - the price depends on that as well. This system is attested for the use in the Czech Republic and its operator does not have to apply for any kind of licence or permission to operate. For our purpose, we chose the LaserBit LB-1500 E 100 model which is designated for up to 1500 m span. Its laser output is 70 mW in class 3B, it operates on 785 nm wavelength, and according to technical specification, it reaches the 100 Mbps full duplex speed. The system offers an Ethernet UTP 100 Mbps interface; another optical interface can be chosen instead. The price of a pair of these transceivers was 9,300 Euro without VAT at the time of our tests. The producer guarantees proper system operation in any kind of weather including fog, rain, and snow. The manufacturer also supplies 100 Mbps laser modules for the distance of 150, 200, 500, 1000, 1500, 2500 and 5000 m and 1 Gbps modules for 200, 500 and 1000 m.

We were able to test the laser link operation also in bad weather. Even heavy rain accompanied by thunderstorm or ordinary fogs did not affect transmission speed in any way but the connection failed during thick fogs. The level of fog thickness that may influence the connection functioning depends on local conditions of each line. Our line runs above a field (40 m above the ground) and so the fog there is often much thicker than that in built-up areas within a city. During the five-month operation when LaserBit was connecting the Borská Student Hostel network to the campus network in routine operation, we have noted four network failures during very thick fogs. No failures occurred outside foggy weather. But even including the fog-related failures, the overall system availability reached over 99.5 %. Every minute, a 20 MB test file is transmitted over the line and the results of this long-term transmission measuring correspond to the tests that have been carried out. A backup line (e.g., WiFi) may be necessary for continuous operation should local conditions prove unsatisfactory for a laser link.

We are considering to test the FSO LaserBit connection over a distance of 2.5 km, evaluate the WiMAX technology possibilities and so-called Gi-Fi (Gigabit Wi-Fi), and investigate into other technological possibilities of gigabit free space transmissions in 2005. The interest for these possibilities is also documented by their inclusion into relevant TF-NGN international activities. At the same time, we will continue developing and testing low-cost optical connection transceivers at 100 Mbps and researching other possibilities of further speeding-up while keeping the prices relatively low.

3.7   Parts of International Projects and Grants in Optical Networking Activities

In 2004, the activity participants became engaged in the following parts of international projects and grants.

3.7.1   GN2 SA1 Procurement

The SA1 activity deals with transmission capacity procurement, locating PoPs, facilities, facility maintenance and network operation for transferring or replacing present interconnections between NRENs within GN2 by qualitatively new lines.

The aim is to choose and recommend optimum lines and transmission technologies based on tenders with respect to technical and price levels and availability, and to sign contracts with selected suppliers.

3.7.2   GN2 JRA3

Primary aim of this activity is to map-up the BoD (Bandwidth on Demand) users and their requirements, and to elaborate a comprehensive study on the current state of technologies for the BoD service support.

Secondary aim is to elaborate a detailed BoD service specification. Owing to the fact that the BoD development and deployment is quite complex, this will be realized gradually within four levels according to the growing level of difficulty: single-domain manual provision, multi-domain manual provision, single-domain automatic provision, and finally multi-domain automatic provision.

The third aim is the service implementation itself, where instead of developing new solutions, current solutions will be integrated. The last aim is to test and evaluate the service in real environment.

3.7.3   GN2 JRA4

The JRA4 research activity of the GN2 Multi-Gigabit European Academic Network project gathers knowledge of new experimental network conceptions and interconnects the national testing networks to test new transmission technologies for the GÉANT2 network.

This research activity is focused on testing new services and transmission technologies for the GN2 network in the framework of NRENs and between individual NRENs which have a highly developed testing network based on dark fibres and are experienced in advanced transmission technologies.

The aim is to connect the research activities of European networks and interconnect national testbeds based on the experience in dark fibre acquisition, on the latest transmission technology deployment and on operating such optical lines. Under JRA4, new experience with new types of experimental networks will be gained. These experimental networks will be fully optical, based on dark fibres, using long-distance transmission (LongHaul and UltraHaul), multi-lambda transmissions between end users, etc.

3.7.4   SEEFIRE

There are three basic groups in project goals. The first group sets up strategic goals for the development of regional NRENs, justification and defence of regional NREN roles, identification of countries where governmental support will be necessary for dark fibre acquisition, and spreading the project results outside the region, mainly towards emerging NRENs in the rest of the world (South Africa, Latin America, the Mediterranean, Asia).

The second group of goals involves the creation of the current list of potentially available dark fibres in the region including their types and owners and the documentation of existing technical and administrative experience in fibre infrastructure in the region (on metropolitan, national and regional levels).

The last group of goals involves an identification of suitable technical solutions of optical transmission systems with respect to their technical levels while keeping the prices acceptable (CESNET), finding the companies which are experienced in laying new optical cables, and finding out the conditions and prices of this cable laying with special respect to last miles.

CESNET will be responsible for fulfilling the goals concerning the transmission technologies suitable for the south-east European region.

3.7.5   CzechLight Extension

The CzechLight Extension international project attempts at extending the CzechLight experimental network both in the geographical and functional senses. Cisco transmission and switching facilities for CEF networks will be developed and verified during the project and their applications tested. The nearest step is the change of the original project with respect to current conditions and facilities. Thanks to the fact that the financing conditions have been solved, the project can start successfully.

3.7.6   The Czech Republic Grant Agency

The aim of the common CESNET-ÚRE-FEL ÈVUT Optimisation of data transmission at 10 Gbps over G.652 fibres with respect to maximum transmission distance without deploying in-line EDFAs project is the analysis of the possibilities of NIL transmission optimisation over G.652 and G.655 fibre routes at 10 Gbps using Raman pumped transmission fibre and signal amplification by erbium-doped amplifiers. The results of numerical analysis will be verified experimentally under laboratory conditions. Use of Bragg grating for GVD compensation to substitute the DCF modules will be experimentally investigated as well. For laboratory experiments, a Cisco ONS 15454 SONET MSPP system with two OC-192 cards (10 Gbps transmission speed) will be used, too. We expect that the simulation and laboratory test results will be used in the CzechLight experimental networks (and elsewhere in case of interest, e.g., in the GN2-JRA4).

3.7.7   Information Society

The aim of the common CESNET-ÚRE Time division multiplex pumped Raman fibre amplifiers project of the Information Society programme is a theoretical analysis, experimental realization and quality verification of wideband Raman fibre amplifiers with time division of pump sources. The theoretical analysis will be based on the creation of TDM RFA numerical large-signal model proceeding from numerical solution to a set of bound partial differential equations describing all important phenomena occurring in TDM RFA. After the set-up and tuning of numerical programs for TDM RFA behaviour simulation, a detailed analysis of the properties of this type of Raman amplifier will be done and the properties will be compared to the optical parameters of continuously pumped RFAs. We would like to test the simulations and tests results also in the CzechLight, or maybe in other experimental networks.

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