Network (JANET)
3.6 The National Academic Network
university to which it was selling a computer system. These protocols were to be freely available to the academic community.
This situation should be compared with the availability of the connectionless protocols which were favoured by the ARPA community. Any US computer man- ufacturer wishing to sell to an ARPA funded project was required to provide implementations of these protocols. A protocol is like any other piece of soft- ware in the sense that once it has been written and tested, the marginal cost of making another copy is effectively zero. As a result, most US suppliers made the complete protocol stack available at no cost to customers. Naturally at that price, they found plenty of willing buyers.
been in the form of one large switch, based somewhere between Leeds and Man- chester. There would have been one immense drawback to this configuration; if the single central switch failed, the entire network would fail. This was an important consideration. In accordance with the Government’s buy British pol- icy, the Network Executive sourced its switches from within the UK. The only available switches were based on a GEC manufactured system. These were ini- tially run with software written at the Atlas laboratory, but it was decided that the GEC written software should be used. The reliability of these switches was poor. We had agreed targets of a mean time of 2000 hours (approximately 3 months) between faults on the switches, and a mean repair time of 4 hours.
These targets would have given an availability of 99.8%. In practice the reliabil- ity of the switches varied very widely. The best switches did achieve the target, but the worst were failing every three or four days. The hardware was quite good, but the software had frequently to be reloaded, this being the quickest way of dealing with its faults. The situation was not helped by the fact that even a small switch required as its base a system of approximately the same power as the Atlas computer. This was a major psychological barrier; part of the so-called procurement policy was an insistence that where a university’s total require- ment for computer power exceeded one Atlas power, then the University was limited to buying a UK manufactured system. There were those who argued that rather than using this much computer power simply to enable traffic to flow in a network, it would be more effective to use these systems to provide “real”
computing to users.
The transfer of control of the separate research council and Regional Computer Centre wide area networks to the Executive took place during 1983. There was no wholesale change of staff or equipment. Rather, the Executive proceeded by placing a contract for a Network Operation Centre (NOC) with each site that ran a switch. These contracts laid down staffing levels needed to operate the NOC;
the staff concerned remained as employees of the local university or research council, but the cost of employment became a charge against Computer Board funds. This had the advantage of ensuring continuity of employment for the individual staff, and safeguarded aspects such as seniority and pension rights, and reduced the loss of highly qualified staff. The Board took over the costs of equipment maintenance, and of leased lines.
3.6.1 The Formal Start of JANET
The formal transfer of equipment and the start of the single academic network took place on 1 April 1984. One of the agreed objectives of the single network was to replace the multiple funding sources of the existing networks, i.e. The Computer Board for the universities components, and the separate research council components by a single unit, funded wholly by the Board. The April 1st date was conveniently near to the start of the Treasury Financial year, and this eased the transfer. It was also easily remembered, as being All Fools’ Day, in George Orwell’s year. By this time the network had also acquired a name, JANET.
There are conflicting views as to the origin of this name. It is, of course, a
contraction of Joint Academic Network. For my part, I rather prefer the notion that it was in honour of the Network Units first secretary, Janet Charles.
JANET differed from other networks then operating in the UK in a number of respects. There were two commercial networks, the Post Office’s service, PSS, and a corresponding international service, IPSS. Clearly both of these services charged for use. There were those who would have preferred to charge for the use of JANET. I, and many others, argued strongly that we could think of no better way of restricting the take-up of JANET than by charging. The dominant costs in owning and operating a network are standing charges which do not increase with use. Once the standing charges have been met the marginal costs of using the network are very small. If the charges reflect the standing costs they will appear to users as being very high, but from the perspective of the funding body, these costs must be recovered. Any charging regime will necessitate the development of software to capture usage, at a sufficiently detailed level to enable billing. This software must also incorporate adequate security mecha- nisms to safeguard against misuse. All of this adds non-productive software to what is already a complex product. Add to this the human effort needed to con- trol and manage the accounting and charging system, and there is a large amount of non-productive investment. This non-productive effort acts as a powerful disincentive to users to exploit the network. Mercifully, JANET was, and largely continues to be, a non-charging network. There are exceptions, principally where JANET access is provided to an organization which is not cov- ered by the Joint Information Systems Committee (JISC), the direct successor to the Computer Board which underwrites the costs of JANET for all higher and further education bodies. In these cases there is a fixed annual charge to the organization to meet the cost of the connection to JANET.
Other networks were owned by a single organization, for example those oper- ated by the banks. These networks were used for a narrow range of applications, by a tightly disciplined group of specialist users. In contrast JANET, although technically owned by a single organization, the Network Executive, was answer- able to a large number of organizations, in the form of fifty or so fiercely inde- pendent universities, and several equally independent research councils. The range of applications was large, and open ended; provided that the individual applications conformed to the current version of the protocols, each applica- tion could do as it wished. The number of users was also large; at that time most universities restricted access to their computer resources to members of staff and to graduate students, mostly in Science and Engineering, but this still gave a user community of many thousands. Whatever else might be said of these users, they were in no sense tightly disciplined.
The key to controlling this potentially chaotic situation was that JANET itself ended just beyond the point at which it entered a site. JANET functioned purely as a wide area network between sites, and offered almost no other services. Traf- fic joined JANET at a carefully defined and documented boundary between the source site and the wide area network, and left at the corresponding boundary at the destination site. Provided that the traffic conformed to the published pro- tocols, there was no further control by JANET as to what went on at these two
sites. In particular JANET offered no security against unauthorized access to a connected site’s systems, control of which was entirely the responsibility of the local site. Again, this led to some difficulties in the early stages, with demands from some quarters for JANET to offer security and control of unauthorized use. The fact is that if a service can be misused across a wide area network, it can almost certainly be misused more locally. Turned inside out, this implies that unless a service is secure against being compromised locally, the operators of the service should certainly not even consider connecting it to a network.
JANET was, and is, an open network, accessible with a minimum of formality to users of computer services in its constituent universities and research council sites. From time to time this led to lurid accounts in the press of people who had broken into JANET. We used to liken this to breaking and entering the A1.
JANET offered two value added services:
G access to commercial networks
G a Name Registration Service (NRS).
The charges for using PSS and IPSS contained a fixed element for the provision of a connection, and a usage related element, based on the number of packets sent. It made sound economic sense to provide a small number of access points, for use by the whole academic community, to these commercial services. It was agreed the fixed element of the charges would be met centrally, and that users should meet the usage related charges for their use of these gateways, which would therefore need to incorporate mechanisms for authorization and charging. These gateways operated as centrally managed services available to the whole community.
A large network is continuously undergoing changes both to the configuration of the network, and to the systems accessible via the network. Ensuring that all parts of the network are kept properly informed of these changes is a major administrative task. The NRS was an attempt to ease this task, by partitioning it so that each site could administer the changes it was making. At the outset there was some misunderstanding by users of the purpose of the NRS. The NRS was a means of mapping between the name attached to a service, and the address of that service. In this sense it is not unlike a telephone directory, which gives the telephone number of a subscriber. It was intended to be accessed by a machine rather than a human, and consequently showed a rather hostile interface to even an experienced user. In principal users should not need to know the addresses of services, but should be able to use service names. It took some time to persuade users of this.
3.6.2 JANET User Groups
As well as the technical activities necessary to start JANET, I took great care to establish user groups, and to ensure that these groups had real power. A wide area network has three distinct types of user. Some “users” are technical staff at each site, responsible for the operation of the local computer systems, including of course the site’s local area network and its connection to JANET. In creating
JANET, we were fortunate that nearly all sites housed a computing service, with highly competent staff, who could oversee the running of the connection to JANET. Other “users” are those who simply want to use the network to access some remote facility, or more likely, to access a user at another site. Clearly there are very large numbers of these, and they are usually referred to as end-users.
Usually end-users are individuals, but in some cases they are themselves a service, such as a library, which in turn might have still further users. I took the view that in this case, the end-user was still the Library, rather than the reader, since the reader’s use of JANET was incidental to her work.
I wanted to create a user group which would provide a forum for discussion of JANET’s progress. I insisted on having a single group, containing representa- tives of all classes of user, so that end-users at each site could feel that their views were not being filtered by the staff of the local computing service. As I pointed out above, users of a network can have a very different perception of its reliability from that of those running the network. This divergence can become very serious in the case of a network. The end-users at a site will take the view that the staff of the computer centre are part of the network, and will tend to hold them responsible for failures of all sorts, including those over which the local staff have no control. This can cause needless tension between the staff of the site’s computer centre, and the site’s users. I was anxious to ensure that all concerned were aware of this, and were kept as fully informed as possible. By and large I think the user group was successful in doing this.
Because JANET covered the whole of the UK, the user group was organized on a geographical basis, with seven regional groups; each site sent two delegates to these regional meetings, one from the computer centre, and one end-user. There were also discipline based user groups, representing High Energy Physics and later Library services. The regional and discipline based groups sent represen- tatives forward to a national meeting, and the Chairman of this national group was an ex officio member of the Network Advisory Committee (NAC), the body established by the Board to oversee JANET. I confidently predicted that this chairman would be a member of staff of a computer centre. I am happy to say that I was totally wrong in this prediction, and the first user group chairmen were all end users, and without exception contributed greatly to the work of both the user group and the Network Advisory Committee.
The user group played a valuable role in emphasizing that JANET was not a research network, but a network for the support of research. By this I mean that the main driver for those responsible for running JANET was the provision of a reliable network, not the development of new network components. Of course there were times when in order to properly support a new end user application it would be necessary to develop new network products, but where this was done it was in response to a specific end user requirement. In general however, those who ran JANET were continually surprised by users ability to think of inge- nious ways of exploiting what they were offered.
At least one member of the Executive and I made a point of attending meeting of the regional and discipline based user groups. There were nine of these groups, each meeting at least three times a year. The user groups were enormously
successful. They gave end users a mechanism for making their views known to the Executive and the NAC, with a minimum of formality. They also gave the Executive and me an opportunity to involve users in decision making. This was especially valuable when it was necessary to decide between several courses of action each with advantages and drawbacks, and each achievable within the overall budget. I believe that we were able to avoid a number of mistakes by hav- ing access to such a well informed and highly motivated pool of experience. I shall always be grateful to those many users who contributed to the user group meetings.
3.6.3 Upgrading JANET
The network configuration that we inherited in 1984 was essentially the product of pulling together a number of disparate networks. Its principal advantage was that it allowed us to get a single network operating to a single set of standards up and running in a matter of a few months. However, it was mani- festly not the most economic configuration. Quite simply, it had too many switches, and it was not as reliable as was wished. To improve the network it would be necessary to close down some switches, and remove some links. At the same time, the remaining switches needed to be improved, and the lines between the switches needed to be replaced by higher speed connections. It proved possible to do all of these.
From the outset the NE monitored both the reliability and the traffic levels on JANET. These measurements provided strong evidence of the need to JANET, both to improve reliability and to ease network congestion. As well as the prob- lems with reliability outlined earlier, users, especially those performing interac- tive work at a remote site were experiencing unacceptable delays. Traffic on a network tends to follow a Zipf ’s law distribution, with a few heavy users creating most of the traffic, and a very long tail of users creating only a small part of the total load. It is also sharply periodic, with the busiest hours, typically mid morn- ing and mid afternoon, having traffic loads ten times those of the quieter peri- ods. If one simply measures the average traffic over twenty-four hours, a link or switch may appear to be operating at say 10% of capacity; however, this can con- ceal peak loads, sometimes lasting several hours, when the unit is running at peak capacity. Such a heavily loaded unit can give rise to long queues, which in turn leads to poor response times.
When JANET first started, the only sites allowed to connect were the universi- ties and research councils. However, research council grant holders in Polytechnics were allowed access to JANET. In some cases, a link was supplied directly to the grant holder, but a steadily growing number of Polytechnics had local area networks, and in these cases it was sometimes just as easy to connect this local area network to JANET. Quite often, this was most easily achieved by installing a connection to the nearest University, and within a matter of months of the start of JANET there was agreement that all Polytechnic sites should be connected, either directly or via their nearest university. The opportunity was taken to replace the central part of JANET, which linked London and
Manchester universities, and the SERC’s Rutherford and Daresbury laborato- ries. Much of the additional funding came as a result of proposals for major upgrading of the computing facilities at these four sites, with a consequent need for improved network access particularly for interactive work. The technical situation was also improving, in two senses.
The formation of British Telecom (BT), had led to improved availability of higher data rate connections. This reflected a change in the way these links were supplied. Until this time, the links were provided by using a modem to connect to what was essentially a speech (analogue) circuit. Now, BT were prepared to allow direct access to the digital circuits which had were used to carry traffic between its exchanges. This gave the public access to digital “Kilostream” and
“Megastream” circuits with bit rates up to 64 Kbps and 2 Mbps respectively, much higher than the 9.6 Kbps and 48 Kbps with which JANET started. BT also had equipment which allowed a single Megastream circuit to be treated as a number of separately configurable 64 Kbps circuits, and by using this the NE were able to create what was effectively a fully linked configuration between the four major switches at London, Manchester, Rutherford and Daresbury. In par- allel with this, GEC were able to offer higher speed units to attach to their switches, which allowed these higher line speeds to be exploited.
Welcome as they were, the improvements in hardware were accompanied by an even more welcome relaxation in the attitude towards protocols. By 1986, it was becomingly increasingly clear that the connection oriented coloured book pro- tocols were not competitive with the connectionless ARPA protocols. It is an open question whether this represented an inherent superiority in the connectionless protocols, better implementations of them, or their availability on better hardware. Whatever the reason, the UK academic community had experimented with various means of allowing the two protocol stacks to coex- ist. These experiments had shown that this was technically feasible, and for some five years it was hoped that JANET could operate permanently in this way.
It was not until 1991 that use of the coloured books was finally phased out.