Most people who use the internet in Britain today have never heard of JANET. And yet, if you trace the copper and fibre back far enough, you keep arriving at the same place: a quietly extraordinary network that connected British universities long before anyone else had thought to try. I’ve written before about JANET’s origins, but the origin story is almost the least interesting part. What happened next, through the 1990s and into the 2000s, is where things get genuinely consequential.
This is the story of how an academic network grew up, shed its proprietary skin, embraced the global standard of TCP/IP, and became SuperJANET. And why that matters to anyone who has ever used broadband in Britain.
From X.25 to TCP/IP: The Protocol War Nobody Remembers
JANET in its early years ran on a protocol called X.25, a packet-switching standard that was, for its time, perfectly sensible. The international telecommunications bodies had blessed it. British Telecom understood it. It worked. What it was not, however, was the internet.
During the late 1980s and into the early 1990s, a quiet argument was running through the corridors of British computing departments. On one side sat the OSI (Open Systems Interconnection) model, a vast and committee-designed suite of protocols that governments and telecoms companies favoured. On the other side was TCP/IP, the scrappy American-born protocol stack that ARPANET had used, and that was rapidly becoming the de facto language of global networking. The UK academic community watched this argument with increasing urgency, because JANET’s future depended on which side won.
TCP/IP won. It won because it was simpler, because it was already deployed at scale, and because the researchers who actually used networks preferred it. By 1991, JANET had begun the transition, running what was called the “coloured book” software alongside TCP/IP in a hybrid arrangement that must have been a systems administrator’s nightmare. By the mid-1990s, the transition was effectively complete. JANET was, at its core, an internet network, governed by the same fundamental protocols as everything else. That decision, taken incrementally and somewhat reluctantly, locked Britain’s academic infrastructure into a compatible future with the global web.
What Was SuperJANET and Why Did It Matter?
The SuperJANET network history begins in 1992, when the Joint Information Systems Committee, known as JISC, commissioned a major upgrade. The original JANET had been running at speeds measured in kilobits per second. SuperJANET arrived with something genuinely radical for the time: a high-speed backbone operating initially at 34 Mbit/s, using synchronous digital hierarchy links across dedicated fibre. For comparison, most home users in 1992 were connecting to anything via a 14.4k modem, if they were connecting at all.
SuperJANET connected the major research universities with a spine that could carry real data, not just emails and file transfers, but video conferencing, large dataset transfers between research institutions, and early experiments in what we would now call multimedia. It was funded through a combination of JISC money and research council grants, and it was built on infrastructure leased from BT, which was significant for reasons that would become clear later.
By 1995, SuperJANET had been upgraded again, with the backbone reaching 155 Mbit/s in places. SuperJANET 3 and SuperJANET 4 followed through the late 1990s and early 2000s, each iteration pushing speeds further and extending connectivity to more institutions, including further education colleges and eventually some regional research partners. You can read a detailed technical overview of JISC’s network history on the JISC website, where the engineering decisions of that era are documented with admirable clarity.
The Infrastructure Decisions That Echoed Into Broadband Britain
Here is where the SuperJANET network history becomes something more than academic. The routes that SuperJANET used, the fibre conduits leased and eventually owned, the points of presence established in city centres and university campuses, all of this created a map. And that map, in many cases, became the skeleton on which commercial broadband was eventually built.
When BT began rolling out ADSL broadband to homes in the late 1990s and early 2000s, it was working with an infrastructure that had already been stress-tested by academic demand. The exchange points, the regional aggregation hubs, the long-distance fibre routes between cities: these had been established, argued over, and refined in the context of JANET and its successors. The universities had, in effect, run a decade-long trial of what a national high-speed network looked like in practice.
Regional network operators that emerged in the late 1990s, particularly the Metropolitan Area Networks that JISC funded to connect institutions within specific cities and regions, created local fibre loops that commercial providers could later use or replicate. In cities like Manchester, Edinburgh, and Bristol, the academic fibre rings preceded commercial deployment by years.
There is also the question of peering and the London Internet Exchange. LINX, founded in 1994, became the critical hub where British internet traffic exchanged hands between providers. The academic networks were among the early participants. The norms established there, about open peering, about traffic exchange, about the technical standards for interconnection, were shaped significantly by the practices that JANET had developed.
When Knowledge Left the Campus
One detail that often gets missed in any account of JANET is the human side. The engineers and researchers who built and maintained this network through the 1980s and 1990s did not stay in universities forever. They moved into commercial internet service providers, into BT’s nascent internet divisions, into the startup companies that were beginning to populate the web. They took with them not just skills, but assumptions: about how a network should be run, about peering arrangements, about the importance of redundancy, about what it meant for a network to be genuinely reliable.
In this sense, JANET functioned as a kind of publishing network for technical knowledge, the experience accumulated by its administrators and architects flowing outward into the commercial internet industry in a way that is difficult to trace but impossible to dismiss. The same dynamic had played out with ARPANET’s alumni in the United States, but Britain’s version ran through university computing departments rather than defence contractors.
The analogy holds for content, too. British universities, connected at speeds their commercial peers could only envy, were producing and hosting web content from the earliest days of the world wide web. Tim Berners-Lee had proposed his hypertext system at CERN, but British academics adopted it with extraordinary speed, and JANET was the reason they could.
What Remains of JANET Today
JANET still exists. Operated by Jisc, it now runs as a 100 Gigabit per second backbone, connecting universities, colleges, research institutes, and NHS trusts across the United Kingdom. It is one of the most advanced national research and education networks in the world, though it attracts almost no public attention. The SuperJANET name has largely been retired, absorbed into the evolving identity of the network it became.
But the deeper legacy is in the architecture of the British internet itself. The decisions made in the 1990s about TCP/IP adoption, about where to lay fibre, about how to build high-capacity connections between cities, created a template. Commercial providers did not start from nothing; they built on a foundation that academic computing had already poured.
When we talk about Britain’s digital infrastructure, we tend to focus on the arguments: about BT’s monopoly, about the slow rollout of fibre to homes, about the postcode lottery of broadband speeds. All of that is real and important. But behind those arguments lies a quieter story of an institution that got a great deal right, early, and whose choices still reverberate in the networks we use every day without thinking about them at all.
Frequently Asked Questions
What is SuperJANET and when was it created?
SuperJANET was an upgraded, high-speed version of JANET, the UK’s academic network, commissioned in 1992 by JISC. It initially operated at 34 Mbit/s over dedicated fibre links, a remarkable speed for its era, and went through several further upgrades throughout the 1990s and early 2000s.
How did JANET transition from X.25 to TCP/IP?
During the late 1980s and early 1990s, JANET ran a hybrid arrangement of its existing ‘coloured book’ protocols alongside TCP/IP before completing the transition by the mid-1990s. The shift was driven by TCP/IP’s growing dominance globally and its simpler, more interoperable architecture.
Did JANET influence Britain's commercial broadband rollout?
Yes, significantly. The fibre routes, regional network hubs, and infrastructure decisions made under JANET and SuperJANET created a technical map that commercial providers, including BT, built upon when rolling out ADSL broadband in the late 1990s and 2000s. Metropolitan Area Networks funded by JISC also preceded commercial fibre deployment in several British cities.
Who runs JANET now and what speeds does it operate at?
JANET is currently operated by Jisc, the charity that supports digital technology for UK education and research. The modern network runs at speeds of up to 100 Gigabits per second and connects universities, colleges, research institutes, and NHS trusts across the UK.
What role did JANET play in the early world wide web in Britain?
Because JANET connected British universities at speeds far exceeding anything available commercially, academics were among the earliest adopters and publishers of web content. The network gave university researchers the bandwidth to host, share, and experiment with web technologies from the very beginning of the public web in the early 1990s.