Summary

  • A 1995 paper says IP carried over X.25 reached 90% of JANET’s total traffic by the end of 1992; it does not define that as link capacity.
  • SuperJANET planning began in 1989, so the later figure explains a native-IP backbone decision, not the high-speed project’s origin.

Analysis

Separate projects, overlapping dates

SuperJANET was already being planned before JANET’s IP traffic became a famous percentage. Planning began in 1989; the Universities Funding Council approved first-phase funding in December 1991. JIPS, the JANET IP Service, became available in October 1991 and carried IP over the existing network. The 1994 project account and a contemporary OECD report show that SuperJANET had its own funding and deployment path.

A 1993 paper by Crowcroft and colleagues says JIPS had grown quickly and used about one third of the 2 Mb/s backbone at the time. A different, 1995 account by Kim, Simpson, Hutchison and Scott looks back to the end of 1992 and reports IP-carrying X.25 traffic at 90% of total JANET traffic. The authors say that supported native IP in JANET’s backbone and encouraged more users to switch.

Those percentages do not form one utilization series. The 1993 paper relates JIPS to a 2 Mb/s backbone; the 1995 paper compares IP carried over X.25 with all JANET traffic, without defining the unit in its brief historical passage. Ninety percent therefore does not mean a link was 90% full, or that 90% of universities had migrated. It is evidence for one later operating decision: native IP in JANET itself.

Keeping the old service usable

The 1995 authors identify the spread of local-area networks as the main driver of IP growth. The change was visible in campus computing, not just in a central plan. They also say UKERNA offered services to help applications that still depended on X.25. The backbone was downgraded and withdrawal was intended, but the paper gives no final retirement date. That is a phased transition, not a flag day.

SuperJANET moved in parallel. Its 1992 BT contract covered £18 million over four years, subject to review after the pilot. The OECD report planned a six-site pilot for March 1993 and said the new service would complement JANET. By April 1994, the 1995 account describes a 34 Mb/s SMDS backbone available to 60 sites, alongside a separate 16-site PDH network for ATM research. The high-speed research network and JANET’s native-IP evolution were related, not interchangeable.

The sequence matters: campus use made a backbone change defensible, while support for X.25-dependent services made a safe exit possible. The Follett review treats JANET and SuperJANET as research, teaching and library infrastructure and notes that some institutions still lacked the internal networks needed to benefit fully.

Sources