University network

A university network (also called university network at universities ) is the network of computers in a university . It is mostly connected to the scientific network of the DFN-Verein and thus part of the worldwide internet . It can be used by all university members, often from home as well.

The network thus offers access to diverse information processing and enables comprehensive communication. It is therefore an indispensable instrument for research, teaching and study as well as all administrative processes of a university.

history

As early as the 1960s, terminal networks (terminals for dialog operation on mainframes) and data stations ( punch card input and printer output for batch operation on mainframe computers ) were operated as forerunners of the university networks , via which remote access was possible. First computer-computer connections, e.g. B. via the ALWR protocol, created around 1975 mainly in Lower Saxony between and partly within the universities; This enabled jobs to be sent to remote computers for processing, the results to be returned and files to be transferred.

The data was initially transferred via telephone lines (e.g. from the Deutsche Bundespost, including Datex-P and Datex-L ). Computer networks are now based on their own fiber optic or copper lines, which can also be used to handle telephone services.

From the local network to the backbone

Plans to network the universities became known at the end of the 1970s. Around 1984, some fiber optic and coaxial cables were laid in the first universities and the construction of the networks began. The German Research Foundation (DFG) supported these efforts in 1987 with a network memorandum. Up until the end of 2006, the establishment and expansion of the networks was financed as a construction measure within the framework of the University Building Funding Act (HBFG); the DFG assessed the applications from 2001 onwards.

Choosing the right products was initially difficult because the variety of suppliers of network hardware and software was confusing with almost 100 manufacturers, standards did not yet exist. Topology, transmission speed, cabling material, connection costs and functional scope had to be assessed and tested: baseband, broadband, Ethernet, token ring and token bus as well as the associated protocols and network cards for computers had to be taken into account. Ethernet and TCP / IP protocols finally prevailed and ensured uniform development.

The first small local area network based on Ethernet consisted of a coaxial cable segment to which computers had to be connected at certain intervals if they had an appropriate network card. Such segments were coupled with bridges; Repeaters were used when the cable segments were too long and the signals had to be amplified. The next step consisted of coupling the cable segments within buildings with the help of star couplers and connecting these star couplers between the buildings using fiber optic cables. In addition to the coaxial cables, twisted pair cables (cables with twisted wire pairs made of copper) were added, which eventually became established in building cabling.

When connecting the local networks between the buildings in the so-called backbone, only Ethernet with a transmission rate of 10 Mbit / s (then Fast Ethernet with 100 Mbit / s) was used on the fiber optic lines. Later, FDDI (early 1990s) and ATM (late 1990s) could be used in the backbone, before they were finally replaced by Gigabit Ethernet (around 2001).

By 1990 all universities had finally started to set up university networks. The full expansion in and between the buildings has almost been achieved in many universities for a few years. The university computer centers set the pace ; Operation and modernization of the networks remain their major ongoing tasks. The technological leaps in network components are still hectic: Sometimes products are replaced by better ones after 2 years, every 7 years we see a tenfold increase in the transmission speed, sometimes even faster; So many technologies have to be operated at the same time because you cannot keep up with this speed for cost reasons.

Telephone and computer networks have been growing together for almost 10 years, as the basic technologies converge, Voice-over-IP is a key word for telephoning in computer networks.

Regional networks

Dialing into university networks from the home workplace was made possible on a large scale many years ago using modem and ISDN technology in telephone networks. Sometimes a few 100 dial-up points were made available, and the telephone charges could be made cheap according to contracts between the data centers and telephone providers. These dial-up options have now become meaningless.

Around 1998/99, access from home was supplemented by DSL connections. This achieves connection speeds of a few Mbit / s. Many student dormitories are also integrated via DSL if they are not directly integrated into the university's fiber optic network.

In the local networks there are access points for radio networks (WLAN) that were introduced around 1990, but are not yet nationwide in large universities. They can be used inside and partly outside of buildings. Individual access points have even been specially set up in outdoor areas where students spend a lot of time.

Supraregional networks

In 1979, universities and the Federal Ministry of Research and Technology ( BMFT ) developed plans to promote communication technology; In 1982 the first ideas for a German Research Network ( DFN ) were presented.

At around the same time, the IBM offer for a European Academic and Research Network ( EARN ) with connections to BITNET in the USA, which included the basic services file transfer, remote job entry and e-mail, became known; Dialog operation from a terminal on the local computer via EARN on a remote computer was not possible. EARN started in 1984, was easy to use and ensured worldwide communication.

The DFN-Verein initially supported its members in using the Datex-P of the Deutsche Bundespost and, as a result of its state funding, favored network technology and products based on international ISO standards , the so-called OSI reference model ; The main applications were X.29 dialog, X.400 mail, X.500 directory service and FTAM file transfer.

As a result, there were several inconsistent computer addresses in almost every university in 1989; The situation was characterized by heterogeneous networks and limited properties of the connections. Initially, these connection speeds were 300 to 2400 bit / s, 9600 bit / s were the exception. And in 1991 they were neither sufficiently familiar with the use of e-mails, nor was the availability of even the employees of the data centers consistent.

Internet

The Internet and its forerunner ARPANET were developed at US universities; the latter was an ARPA research project commissioned by the US Department of Defense. Technical and organizational aspects were published in the form of Requests for Comments (RFC) so that all users could participate in the development. The ARPANET was launched at the end of 1969 between 4 universities in California and Utah. At the end of 1974 the Internet Transmission Control Program was specified with RFC 675 , and the term Internet appeared for the first time. After implementing several versions, this program was divided into the TCP and IP protocols ( RFC 793 , RFC 791 ) in 1981 , the basis of the TCP / IP protocol family on which the Internet is based to this day. By the end of 1982 the entire ARPANET (approx. 230 hosts) had been converted to TCP / IP.

From 1983 onwards, the connection with Unix ensured the spread of TCP / IP. The background was that the Berkeley Unix distribution had been expanded to include network capability on the basis of TCP / IP on behalf of ARPA (for Unix version BSD 4.2). In addition, other TCP / IP computer networks came into play, financed by the National Science Foundation (NSF): From 1981 the Computer Science Network (CSNET), a computer network for computer science (ie informatics) and from 1985 the NSFNET, a USA -wide backbone to which regional academic networks could be connected. TCP / IP had become the de facto standard and the most important initial services were Telnet, SMTP mail and FTP file transfer.

In Germany, the DFN-Verein set up a computer network exclusively for science from 1990 (based on the X.25 infrastructure of the Deutsche Bundespost), the Science Network (WiN); the BMFT provided start-up funding. The X.25-WiN initially supported the OSI protocol family, but later also the TCP / IP protocol family. The connection of a university network to the science network thus provided its integration into the Internet. In October 1990 this had blossomed to 313,000 hosts. The connection speeds to the science network, which was later developed into the B-WiN , G-WiN and today X-WiN , could initially only be increased slowly because of the immense costs. For connections of 34 Mbit / s z. B. 1996 to pay 500,000 DM per year. And connections with the US were inadequate for many years.

Starting from the universities, the Internet finally began its triumphal march into business, industry, authorities and the private sector. And the Deutsche Bundespost, as the forerunner of Deutsche Telekom, has learned the basics of Internet service provision.

Organization and regulations

The responsibility for the entire university network lies i. d. R. at the data center; it is about the operation, expansion and management of the

• Cabling, e.g. B. Twisted pair cables in buildings including floor and house distributors, connection points for computers in rooms and the fiber optic network between the buildings,
• Network components that take care of the data transport via the cabling, such as B. switches and routers (including provision of replacement devices and spare parts),
• Network structure, e.g. B. local networks (LANs), virtual and wireless local networks (VLANs / WLANs) as well as backbone or core network for their connection,
• Network integration into the Internet.

The data centers have set up a corresponding department for this purpose, in which the employees of the previous telephone department are already integrated in many locations for the purpose of convergence of telephone and data services.

For the use of this communication system, many university administrations have issued regulations that include: a. regulate responsibilities, operation, security measures and access. Some data centers have already concluded service agreements for network operation with their users. It is z. B. stipulated that in the event of a fault, even a complex switch can be replaced within an hour.

Network technology

Example of the structure of a university network

Network technology is housed in distribution cabinets in special distribution rooms. Not only do the fiber optic and twisted pair cables end in these distribution cabinets, but also the active network components, e.g. B. switches of different power installed. For a secure power supply, particularly important distribution rooms are equipped with an uninterruptible power supply and air conditioning. The distribution rooms are only accessible to the responsible employees of the data center in order to prevent uncontrolled changes and manipulation.

Since the science network (X-WIN / C-WIN) of the DFN-Verein is meanwhile i. a. Reached in two ways, these two connections are used for mutual protection in the event of transmission disruptions. The corresponding distribution cabinets are usually located at different locations in the university and are connected to one another via fiber optics. The connection points outside are particularly powerful switches for connecting networks of different facilities, such. B. the network of the university, a university of applied sciences, student dormitories or research facilities, as long as they are available on site and cooperate accordingly (Inter-Core, WNM access network, see sketch).

A hierarchical university network is outlined as an example of the structure of a network:

• A few core switches serve as the top core level, via which the fiber optic cables and, above it, the information flows to important location areas (natural sciences, humanities, ...) are distributed. Switches for the WLANs and for the various security measures (security) are often connected to these core switches.
• In the location areas, i.e. the midrange supply level, switches of medium power are used. These are also used to connect the data center, in which storage and computing capacities as well as other important servers of the university are concentrated.
• From here fiber optic cables lead on to individual buildings or small building groups on the distribution level with additional switches. The backbone ends here.
• The backbone level is followed by the very large number of edge switches that reach the network-capable end devices in the building or from the floor via twisted pair cables. Depending on the size of the university, this can be some 10,000 devices.

The number of switches increases from top to bottom and their transmission capacity decreases. The location of the backbone switches is of little importance, because these devices can be used virtually, i.e. flexibly configured and monitored remotely. In contrast to all outdoor areas, fiber optic cables are generally not used in buildings because this would be too expensive.

The transmission speeds in the university network range from 10 Mbit / s for workstation computers to 10 or 40 Gbit / s and more on the various levels of the backbone and for important servers. The connection capacity on the science network can be assigned differently, it can reach up to 10 GBit / s. The capacity can be adapted to the needs of the university at affordable costs, and operations are stable and reliable. X-WiN is one of the most powerful networks in the world today.

The currently used IP protocol is IPv4. It is about to be replaced by IPv6, both locally and on the Internet, so that global networks can continue to grow.

Management and security

Since the highest levels of availability, long-term performance and extensive security are expected from the networks, numerous management instruments are used for operation, monitoring, fault detection and rectification. While earlier network components, such as B. star couplers and bridges were equipped with few management functions, that has changed fundamentally with modern switches. The redundancy of important network components as well as the configuration and change service are of particular importance for the stability of the network.

Large networks can only be operated if a powerful database is available for all the details of the network components, connection points, cabling, the end systems with their names and addresses, the responsibilities, etc.; because this extensive data must be able to be accessed quickly and from all locations, especially when troubleshooting. In universities with a few 100 buildings, of course, exact floor plans, in which the copper and fiber optic cables are documented, must be digitally available.

Many approaches should simultaneously contribute to the security of the network against attacks: Firewalls, intrusion detection and intrusion prevention systems, stateless packet screening and VPN technology are some of them. For the purpose of greater flexibility, they are operated as virtually as possible, so they can take effect at freely selectable points without being directly available there.

Access to the network is not permitted without access controls for user authentication. Data can be encrypted in transit. Since not every single network connection can be secured according to individually defined criteria, networks are structured, e.g. B. an institute, in zones with similar requirements and standardized safeguards; in this way z. B. Zones for servers, administrators, staff with or without access to personal data and for students can be distinguished.

Network services and applications

Web and e-mail are among the most popular services on the net. E-learning, video conferencing, video streaming, audiovisual techniques, and others are rapidly growing. The services are provided with the help of servers on the network, from the computer center or from faculties / departments or individual institutes. A central identity management enables the administration of roles and rights of all university members on these servers.

The world's web servers are accessed more than 10 million times a month from a large university, and many thousands of GBytes are accessed in the process. The university receives over a million e-mails a day, 95% of which are spam e-mails, which fortunately are automatically deleted. Access to a wide range of (virtual) servers for a wide variety of applications, in particular to high-performance and high-performance computers, to storage capacities including archive and backup systems as well as print services, require powerful networks.

In many places, students and scientists can get direct and secure network access (roaming) as guests at a foreign university using their own laptop. As a result of the networking, legal and data protection issues are increasingly coming to the fore, even beyond the university boundaries, and help is offered by the DFN-Verein.

Web links

• Chronicle of the ZKI including numerous sources, u. a. to the ALWR protocol
• Website of the DFN-Verein

Individual evidence

1. ↑ P. Grosse, W. Held, J. Radloff, G. Tomaselli: History of the cooperation between the computer centers in research and teaching. In: PIK , Volume 33, 2010, Issue 1.
2. ↑ 40 years ZIV - 20 years LAN - 20 years CIP . ZIV University of Münster, Inforum special edition , December 2004.
3. ↑ Network memorandum - Necessity and costs of modern telecommunications technology in the university sector (PDF; 863 kB) DFG, Commission for Computing Systems of the German Research Foundation, Bonn 1987.
4. ↑ IEEE 802.3 in the English language Wikipedia. Ethernet IEEE 802.3 , over fiber: 10 Mbit / s 1993, Fast Ethernet around 1995, 10 Gbit / s 2003, 100 Gbit / s 2010.
5. ↑ ^{a b} RFC 1 with the title Host Software dates from April 7, 1969, RFC 791 on IP and RFC 793 on TCP from September 1981.
6. ^ National Science Foundation Network (NSFNET) in the English language Wikipedia
7. ^ Number of Internet Hosts . ( Memento of the original from June 14, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Internet Systems Consortium.  
8. ↑ H.-M. Adler, P. Eitner, K. Ullmann, H. Waibel, M. Wilhelm: X-WiN - The network infrastructure of the German Research Network (PDF; 1.3 MB) DFN-Verein, 2009.
9. ↑ R. Vogl, M. Speer, N. Gietz, L. Elkemann: Network concept, network development plan, operating and management concept, personnel situation . ZIV University of Münster, April 7, 2010.