EUNIS97, Grenoble (France) 9-11 September 1997

Ref: 032402

TEN-34 CZ-- High Speed ATM Network at Czech Republic

Ludek Matyska

Introduction

Not unlike in the USA, the nation wide computer network infrastructure of the Czech Republic was founded and built by universities and other academic institutes. While the first lines connecting Prague, Brno, and Bratislava were provided as an off-spring of the IBM Academic Initiative of 1990, the universities, financially supported by the Ministry of Education soon established an informal consortium under the name of CESNET (Czech Educational and Scientific NETwork) which took care of the Internet connectivity of gradually all 23 Czech universities. Since the last year, the intercity connections were based on leased lines (lend from IBM and SPT Telecom, and later on using microwave links from Czech Radiocommunications) with capacity ranging between 64kb/s to 2Mb/s (between Prague and Brno). This must be compared with the much higher throughput of local and especially metropolitan area networks, where FDDI (at 100Mb/s) or even ATM on 155Mb/s were already used. The largest metropolitan networks of Prague and Brno were both using fibre optic (leased at Prague, owned by Masaryk university Technical university in Brno) and gradually upgraded the whole MANs from 64kb/s metalic leased lines through 10Mb/s Ethernet to 155Mb/s ATM.

In the last year, under the pressure of inevitable changes in the ministerial financing policy the CESNET transformed from an informal consortium to a legal body. The company is fully owned by universities and Academy of Sciences (they all have a kind of share relative to their annual subscription) and it is a non-profit organization whose primary goal is to provide infrastructure for academic community of the Czech Republic. To some extent CESNET is also providing usual Internet services to commercial customers.

Through the CESNET liaison Czech Republic was an active member of initial stages of the pan-European high speed networking project, the TEN-34, Trans-European scientific Network (as a parallel infrastructure to the Americas' 45Mb/s lines). It was not possible for CESNET to proceed further the initial stage as joining the TEN-34 project required an existence of national high speed network (operating at 34Mb/s at least), a commitment from the telecommunication operator and an appropriate financial budget. This all was beyond the that time Czech republic (and CESNET) capabilities. However, the steps initiated by the European Union had their influence on the Czech government as well, and it launched the TEN-34 CZ program at Spring 1996.

TEN-34 CZ program

This program was officially supervised by the Ministry of Education and it had two parts:

1. To build a national high speed network connected via an appropriate link to the trans-european high speed backbone.
2. To support research projects requiring and utilizing the high bandwidth.

While there were 33 projects submitted in the second category, the first one was covered by just one proposer--the CESNET company. After some hesitation, which was primary caused by the fact that no else decided to submit a project in the first category, and which postponed the start of the project till October 1996, Ministry of Education accepted the proposal and gave the project realization to CESNET. This have started the era of high speed nationwide academic backbone in the Czech Republic.

A total of 16 projects were accepted in the second category, with different subjects belonging roughly to the following categories:

• The remote access to high performance computing facilities, including the trial to use them synchronized for large scale distributed computing. A representative of these projects is the Center project, presented at this conference [1].
• The videoconferencing, telepresence and teleworking.
• Web-based multimedia storage and retrieval systems, both for research and educational activities.

The final decision to support the projects was taken in October, 1996, when the Minister of Education signed the projects' acceptance.

TEN-34 CZ infrastructure

The primary goal of the TEN-34 CZ program was to build the national high speed computer network and to connect it directly to the TEN-34 European backbone.

While six companies took part in the initial CESNET tender for the intercity lines provider, only the proposal from Czech Radiocommunication was acceptable. The Czech national telecommunication operator, SPT Telecom, took part in the bid, but offered lines with just 2Mb/s at the usual commercial price (without any reductions). The Czech Radiocommunications offered leased microwave lines for 34Mb/s with the promise for 155Mb/s lines in 1997 (if requested in advance). As there was very good experience with their 2Mb/s lines, the challenge was taken to be part of the research and development nature of the whole project and the TEN-34 CZ backbone is built on top of microwave lines. The lease conditions require that there is no transfer error during 72 hour period before the line is accepted.

The initial international connectivity was provided by SPT Telecom, because there was no other possibility. However, as SPT Telecom offers only 2Mb/s lines and the TEN-34 backbone requires at least 10Mb/s for the national link, two 2Mb/s lines were leased for the first half of the year 1997. They connect Prague with Munich and Stockholm European Internet crossroads. The new tender for international connectivity, which will join Prague with the TEN-34 point of presence at Frankfurt am Main, was won by Global One, the consortium of German Telecom, France Telecom, and Sprint. While they offered full 34Mb/s fiber optic based leased line, just 10Mb/s will be used, the remaining capacity being free for some experiments and/or for direct transatlantic link.

The national TEN-34 CZ backbone connects metropolitan area networks in nine cities, covering thus a substantial majority of all the universities in Czech Republic. The MANs connected are operated by individual universities or their consortia and in this way the whole TEN-34 CZ network is directly or indirectly operated (and mostly also owned) by Czech universities. The cities connected are Prague, Brno, Ceské Budejovice, Hradec Králové, Liberec, Olomouc, Ostrava, Plzen and Pardubice. The largest MANs, located in Prague and Brno, are already running on up to 155Mb/s, but the smaller MANs and university networks are close behind them (some running FDDI rings, other upgrading gradually to ATM on 155Mb/s; at Liberec two main switches are already connected by a 622Mb/s ATM link).

Technical realization

The TEN-34 CZ is realized as a pure ATM network with IP services on top of it. The TEN-34 CZ backbone connects the above mentioned cities and each connection point is equipped by one ATM switch and one ATM router. All the switches and routers are provided by CISCO systems, the TEN-34 CZ uses CISCO Lightstream 1010 ATM switches and the CISCO 7500 series ATM routers. Each switch is equipped with at least one E3 link, connecting it to the radiowave backbone, and at least two OC-3 (155Mb/s) links, one to the router and the second one connecting the TEN-34 CZ backbone to the metropolitan (local) area network. The routers primary serve as virtual LAN routers, but they are also providing a connection point for the local FDDI rings (as, e.g., at Ceské Budejovice or Plzen) and they usually have several Ethernet ports as well for diagnostic, maintenance and experimental purposes.

Although ATM is its primary interconnection protocol, currently only IP services are provided by the TEN-34 CZ network. The primary protocols are LANE version 1.0 with SSR (Simple Server redundancy, the enhancement implemented by CISCO), classical IP (as specified by RFC 1577) and RFC 1483. The TEN-34 CZ backbone routers use PNNI Phase I dynamic routing with support for quality of services. The same signalling protocol is used by some of the metropolitan area network routers connecting these MANs to the TEN-34 CZ backbone. The remaining MANs use IISP static routing, which is redistributed to PNNI.

One of the most serious problems in building the TEN-34 CZ network was the separation of the pure academic network traffic from the commercial traffic of companies using CESNET as their Internet provider. The TEN-34 CZ project is a purely academic undertaking and, according to the rules, no commercial traffic may use TEN-34 links for transit. While the TEN-34 CZ backbone is built as a parallel network to the already existing CESNET intercity infrastructure, metropolitan area networks were used to transfer both academic and commercial traffic. Two basic approaches were implemented:

1. The MAN was ``purified'', i.e., the academic and commercial traffic use different physical lines. The lines with non-academic traffic are connected to the original CESNET backbone, while the academic (TEN-34 compliant) lines are connected both to the original and the new TEN-34 CZ backbone. This is the preferred realization.
2. The MAN uses virtual LAN technology to logically (although not physically) separate academic and non-academic traffic. Special internal routing policy is adopted in these cases, with ``policy routing'' (where the routes are selected with respected to the originating address) and selective redistribution of OSPF/EIGRP routing information to avoid commercial packet transit through the TEN-34 CZ backbone. A non negligible increase in router load was observed by the use of policy routing (a 20% load increase is not uncommon), and the tables needs a lot of maintenance to work properly.

The original CESNET intercity infrastructure is used as a ``backup'' of the TEN-34 CZ backbone. All MANs (or, more precisely, all the academic parts of MANs) are connected to two autonomous systems: the TEN-34 CZ backbone and the original CESNET backbone. The commercial parts may use only the original CESNET backbone. Both backbones use the OSPFv2 routing protocol.

While MANs usually provide connectivity for both the academic and non-academic users, they are not used for transfer between the TEN-34 CZ and Internet. There is only one peering place between original CESNET and TEN-34 CZ networks, at the CESNET headquarters in Prague. The OSPF and ``backdoor'' BGP protocols are used for this purpose. The dual connectivity of MANs is used for TEN-34 CZ backup only.

Use

The whole TEN-34 CZ backbone serves two main purposes: (i) providing an appropriate high speed infrastructure for research projects and (ii) providing a high speed academic interconnect. Internally, the TEN-34 CZ network is also used to test new up-to-date information technology in slightly unusual conditions: (i) pure ATM over radiowave links on E3 (with planned increase to OC-3 in 1998 for the Prague-Brno link), (ii) the use of QoS in a mostly IP over ATM environment.

Due to the lack of interest from the national teleoperator, the whole TEN-34 CZ infrastructure is in fact operated by the academic company CESNET. There are plans to use this unique situation for experiments with dynamic bandwidth management and allocation, with the aim to combine the ``best effort'' services of the classical Internet IP protocol with the new more advanced possibilities provided by ATM networks. A part of the total capacity will probably be used for www caches and ftp mirroring services, while the rest will be divided between the ``usual'' (unspecified) academic traffic (using UBR and/or ABR) and dedicated ``links'' for the individual scientific experiments (videoconferences, wide area distributed computing[1], telework, vizualization, ...). It is expected that experience on dynamic bandwidth splitting and allocation gained during this ``experimental'' stage will be used as a basis of future academic infrastructure management.

As already mentioned, the TEN-34 CZ program encompasses not only the infrastructure building, but its use as well. These ``pilot'' projects will test the feasibility of adopted infrastructure implementation while opening to researchers an easy access to the high speed network. These projects may be also seen as forerunners for the rest of academic community, serving as examples of potential advantage of high speed interconnects.

Conclusion

The TEN-34 CZ project is a part of a trans-european activity to increase the general network throughput on both the national and international levels. The backbone was officially ``opened'' on June 17th in Prague in the presence of representatives of government and Parliament of the Czech republic. The backbone uses E3 radiowave transmitted links, with pure ATM and IP over ATM as the primary services. The whole backbone, which connects nine cities in the Czech republic, is operated by CESNET, a non-profit company founded and fully owned by Czech universities and Academy of Sciences. The TEN-34 CZ is fully financially supported by a three year grant from Ministry of Education.

References

1

L. Matyska, E. Hladká: Center-- A distributed computing center of the future?, EUNIS'97, Grenoble, France, September 1997.

Copyright EUNIS 1997 Y.E.