Section 3.2 CSNET, The Computer Science Network

by Lawrence Landweber


Networking was still in its infancy in the 1970s.  The ARPANET became a production network in 1975 and by 1981 comprised a few dozen sites, all of which were government contractors and installations.  Even in its small community, the ARPANET quickly demonstrated a remarkable enhancing effect on productivity, speed, and quality of research.  The CSNET founders set their sights on providing similar networking services to the entire US computer science education and research community.

In 1979, a small group led by Denning (Purdue), Farber (Delaware), Hearn (RAND) and Landweber (Wisconsin) began planning CSNET.   Encouraged by Kent Curtis, then at the NSF, these four rallied the computer science community’s support, resulting in NSF approval of a $5M, five-year proposal in 1981, with these initial goals:

  • Open to all computer researchers (initially in US, later internationally)
  • Logical network comprising physical subnets (initially ARPANET, GTE Telenet, and CSNET’s Phonenet)
  • Affordable networking services, ranging from full ARPANET functionality to email relaying, plus directory service and help center
  • Self-governing, -sustaining, and -supporting within five years
  • Members to include university computer science departments, corporate computer research units, and government agencies.

In 1986 at the conclusion of the five-year CSNET was flourishing as a production-oriented Internet infrastructure supporting a large, open research and education community. By offering multiple connection types, it made it possible for the entire CS community to participate in the Internet.  As important, it mobilized the CS community into a major international experiment in large-scale collaborative networking. 

By 1986, more than 165 university, industrial, and government computer research groups serving more than 50,000 researchers and students, belonged to CSNET and accounted for 1000 Internet hosts.  All promised network services were operational and numerous networks outside the US were connected.  CSNET was self-supporting and had significant industry funding.  CSNET clearly demonstrated, for the first time, that users were willing to pay for network services.

CSNET actively collaborated with colleagues in other countries, supporting and often enabling the international expansion of the Internet.  Early international partners included Japan (Jun Murai), Korea (Kilnam Chon), Germany (Werner Zorn) and Israel (Shmuel Peleg).   They used CSNET software to establish connectivity to the US (and thereby to the Internet) and, in some cases, to operate their domestic networks.

CSNET’s influence did not end there.  It was critical to the foundation of NSFNET (1985).  It gave NSF confidence that it could lead large-scale networking projects; it provided experience with policies such as open access, international cooperation, commercial participation, community governance, and network service centers; it demonstrated that computer scientists would devote resources to pay for networking services. Many CSNET alumni played major roles in establishing NSFNET. Together with its associated regional networks and peer networks in other countries, NSFNET became the backbone of the Internet, laying the foundation for a worldwide Internet.  As a precursor to NSFNET, CSNET was a remarkable achievement.

CSNET merged with BITNET in 1988 and was disbanded in 1990 when all its institutions moved into NSFNET.  The NSFNET itself was disbanded in 1995 because all its members received Internet services from commercial ISP’s or from the NSF-funded VBNS (Very high-speed Backbone Network Service).


CSNET Architecture

CSNET’s basic infrastructure was a system of systems: dialup email exchange (Phonenet), TCP/IP over X.25 public networks, name and directory service (Name Server), and high performance network gateways.  CSNET developed the first community network Coordination and Information Center, a prototype ISP.  These systems contributed new technologies, protocol understandings, and access methods.

Phonenet (Delaware)  Phonenet was the entry-level service for CSNET.  Many small institutions lacked the equipment, expertise, or budget needed for full TCP/IP networking.  Phonenet met their needs well.  Its mail protocol presented the same interface as ARPANET’s SMTP.  It was based on MMDF (Multi-channel Memo Distribution Facility) to relay mail between systems over lower level channels including phone connections, terminal drivers, and X.29/X.25 packet networks.  MMDF allowed sites to push or pull queued mail (and attached files) with either of CSNET’s two relays.  The MMDF software enabled about 60 departments to join CSNET during the first year.

TCP/IP over X.25 Network (Purdue)  This CSNET component allowed full Internet participation.  It used GTE Telenet, a public packet network based on X.25 protocols.  It sent IP datagrams across X.25 virtual circuits, and it avoided circuit setup charges by multiplexing several TCP sessions over a single X.25 circuit.  Affiliated networks in other countries used either this software or MMDF to connect to CSNET and, in some cases, in their domestic networks.  Later, the University of Wisconsin team extended this by implementing the full TCP/IP protocol suite for IBM VM systems (WISCNET).

Name Server (Wisconsin)  This early directory service was a user-maintained database that looked up the email address of any CSNET user when searched by name or by descriptive keywords.  It introduced several new concepts for directory management: distributed database, keyword search, mail integration.  Similar functions appeared a few years later in the Internet DNS (domain name service) and various white- and yellow-page services.

Mail Relay and Gateways (Delaware, RAND, Wisconsin)  VAX 750 machines installed at Delaware and Rand provided gateways between ARPANET, CSNET X.25 and Phonenet; they were the earliest examples of a multi-protocol gateway.  Wisconsin later implemented a gateway that connected Internet and OSI X.400 mail.

Coordination and Information Center (BBN)  The CIC was the first community network infrastructure support organization.  It helped members with technical problems, software downloads, new accounts, billing, installations, and configurations.  The center was, in effect, the first ISP.

CSNET Organization  CSNET was chartered to be a self-governing, self-sustaining representative organization of its members.  It was governed by a management committee, initially comprised of the four founders  (Denning, Farber, Hearn, Landweber). The CSNET organization evolved into a consortium of the participating universities and laboratories.  NSF asked UCAR (University Corporation for Atmospheric Research) to assist the young organization during its early years.  CSNET established a viable membership organization, set up bylaws, and held elections of its representatives and officers.  By the time the NSF contract expired in 1986, CSNET was collecting sufficient revenue from its 165 member organizations.


CSNET Contributions

CSNET bridged from early networking research to networking as a pervasive collaborative infrastructure.  In the process it built an extensive networked community.  In 1981 only a few computer science departments and industrial research labs were participating in the ARPANET.  CSNET quickly brought networking to the enthusiasts and gradually won over the skeptics.  By 1986 the entire US computer science and computing research community was part of CSNET.  CSNET helped researchers in many other fields appreciate the powerful enhancements to research and education from widespread Internet connectivity.  All this gave NSF the confidence to undertake the NSFNET, which became the backbone of the modern Internet.

CSNET helped spread networking around the world.  CSNET advised and collaborated with groups in other countries and made CSNET-developed technology available to them.  Important early examples are collaborations with Jun Murai (JUNET) in Japan, Kilnam Chon in Korea, Werner Zorn in Germany and Shmuel Peleg in Israel. CSNET provided these and other countries their first connection to the Internet. In addition, many other countries benefitted from their participation during the 1980s in the International NetWorkshops organized by Landweber under the auspices of CSNET.

CSNET pioneered the university-industry-government partnerships that characterized future US networking.  Industry supported CSNET by paying significantly higher dues than universities and by contributing equipment and employee time.  Subsequent projects including the NSFNET, the VBNS, and the Gigabit Testbed all succeeded because of industry support.

CSNET negotiated key policy decisions that opened the Internet to industrial and international computer researchers.  In one key agreement, ARPA permitted CSNET to authorize new sites, including affiliated networks in other countries, to connect with the ARPANET.  In another, CSNET negotiated an NSF policy that permitted industry research laboratories to join CSNET.

CSNET opened the Internet to all US computer research groups by dramatically reducing the cost of participating.  In 1983, the cost of a connection to ARPANET was about $110K per year.  Connections were hard to get because DoD policy restricted them to government agencies or contractors of those agencies.  CSNET’s Phonenet cost about $9K annually including dues.  CSNET’s IP-over-X.25 protocol via the commercial Telenet packet-switching service cost about $20K annually.  The lower costs were quickly reflected in the participation numbers.  By 1986, CSNET’s 165 member departments brought up to 50,000 researchers and students into the Internet.


CSNET was the first production research community networking system using the Internet protocols.  It introduced the education and research community to the Internet.  It spread the Internet to other countries. It gave NSF confidence that it could manage a complex network project successfully, allowing NSF to undertake NSFNET with CSNET as a prototype.  NSFNET became the Internet backbone.  In then end, CSNET affected the entire Internet, not just the CS community.

Jungbae An,
Sep 27, 2012, 12:51 AM