- 240 - THE PROVISION OF WIDE-AREA NETWORKING FACILITIES Dr Barrie J Charles Joint Network Team of the Computer Board and Research Councils, c/o Rutherford Appleton Laboratory, CHILTON, Didcot, Oxon 0X11 OQX, UK ABSTRACT The academic community in the United Kingdom is currently engaged in an extensive programme to provide comprehensive networking facilities within and among the 47 universities and numerous research institutions in the British Isles. The programme is described and the possible provision of similar facilities on an international scale discussed. 1. INTRODUCTION Since the 1960s, funds for large scale computers in universities and academic research institutes in the United Kingdom have been provided centrally through organisations reporting to the Department of Education and Science. This central funding made possible the establishment of national or regional facilities designed to handle the needs of users which could not be met by an institution's local computing equipment. The distance between these users and the central machines encouraged the early establishment of data communication facilities. Today the primary requirements for wide-area networks are seen as: access to large national or regional centres; facility or resource sharing between sites; database access; electronic mail; software distribution; a tool for multi-site scientific collaborations; a means for the itinerant worker to access his home base. Many of these activities are also now becoming practical internationally and local networks are seen as satisfying similar requirements on a smaller geographical scale. - 241 - HISTORY During the early to mid 1970s many separate networks were set up in the UK academic community. These were based either on the packet- switching techniques made popular by the advent of the ARPA network in the United States or on proprietary RJE protocols such as IBM HASP, CDC 200UT or ICL 7020. Growth during the 1970s led to a large increase in the number of point-to-point private lines and a number of arrangements on each site to access each distinct network. The Joint Network Team was formed in 1979 as the result of the recommendation of a former body set up by the various organisations responsible to the Department of Education and Science. Its objective is to coordinate the evolution of networking so as to arrive at a situation where uniform arrangements are provided to allow any user to access any facility. THE NETWORK MODEL The scheme whereby useful network connections can be established without prior development work by the parties involved is now known as Open System Interconnection. To achieve a useful connection there must be an interconnection path between the systems and the systems must agree how they are going to interwork. The interconnection path will be made through one or more networks and the interworking will be achieved by agreeing on the high level protocols (or rules and procedures) to be used for eg, terminal access, file transfer etc. The model for the provision of networks in the academic community to achieve interconnection between systems is illustrated in figure 1. It is a hierarchical scheme where one or more wide-area networks are used to provide a national system for linking together sites and each site is equipped with one or more local networks. In the short-term, systems on a site may be directly connected to the national network. Figure 1 - 242 - To achieve interworking, an agreed set of protocols is required. Protocols are usually built up in layers each forming a separate level of the communications hierarchy. There is now an ISO draft standard which divides this hierarchy into seven layers. These range from the physical layer which describes the electrical connection to the network up to the applications layer which will handle, for example, file transfer procedures. Unfortunately, although there is an international standard on how the hierarchy should be built up there is no accompanying set of protocols to be used for each layer. Because of the timescales associated with such complex international agreements, it is likely to be many years before there is such a complete set. Using the expertise gained in the early 1970s, a number of protocols have been defined in the UK to fill the gaps left by the lack of international standards. The current complete set of protocols adopted by the academic community for Open System Interconnection is as follows1-6: CCITT X25 for packet-switched network access; CCITT X3/X28/X29 for terminal access; TRANSPORT SERVICE ("Yellow Book"); FILE TRANSFER PROTOCOL ("Blue Book"); JOB TRANSFER & MANIPULATION PROTOCOL ("Red Book"); ARPA MAIL PROTOCOL ("Grey Book"). The last four protocols are regarded as interim and will be replaced once international standards are firmly established. 4. REALISING THE MODEL The Joint Network Team has adopted the following approaches to ensure the model is turned into a practical reality: 1. The placement of development contracts for machine protocol packages and network components: the resultant products are then installed widely in the community using centrally-provided funds; 2. The protocols are included as mandatory items in Operational Requirements for all new major computing systems to encourage the provision of manufacturer support; 3. Detailed technical advice is given to the providers of services and the funding bodies in the evolution of communications arrangements; - 243 - 4. Collaboration within the community is ensured by way of workshops, meetings, committees etc. 5. THE CURRENT STATE National communications are currently provided by two separate wide-area networks: the public packet-switched network (Switchstream 1 or PSS) and the private X25 network set up by the Science and Engineering Research Council (SERCnet). These two networks are interlinked by a gateway which can ensure communication between a system on one network and a system on the other. There are currently 25 X25 connections to PSS from 25 community sites and around 100 connections to SERCnet from about 55 sites. Approximately 20 different types of system are connected. The provision of local area networks is at a somewhat earlier stage of development. Local X25-based communications are generally being supplied using GEC 4000 based Campus Packet-Switching Exchanges and terminal concentrators (PADs) supplied by Camtec Electronics. Service networks of this sort are now installed on 7 campuses and planned for 16 further sites. Cambridge Ring ("Slotted Ring") networks are currently installed at 3 institutes and planned for 8 further sites. The following systems have been connected to these networks and in general support most of the protocols listed above: Honeywell/Multics DEC10/TOPS10 Honeywell/GCOS DEC20/TOPS 20 IBM/VM VAX/VMS IBM/MVT VAX/UNIX IBM/MVS PDP-11/UNIX CYBER/NOS PDP-11/RSXllM ICL 1900/GEORGE 3 PDP-ll/RT-11 ICL 2900/VME LSI-ll/RT-11 PRIME/PRIMOS GEC 4000/OS4000 Most of the packages are in a form suitable for installation at other sites and are supported either by manufacturers or by universities under contract to the Joint Network Team. Figure 2 shows an example campus, the University of Exeter, with X25-based local communications. Terminals connected to PADs can access either local hosts connected to the X25 switch or (via the gateway) any host connected to SERCnet or PSS. International access is also possible - 244 - Figure 2 Example Campus - University of Exeter ICL through the connections between PSS and the public networks in other countries. File transfers can be initiated between local machines and remotely, and jobs prepared on one machine (the ICL System 4 or the PDP- 11 UNIX) are routinely submitted for execution elsewhere (eg on the ICL 2900 or SERCnet hosts respectively). 6. CONCLUSIONS FROM UK EXPERIENCE The UK academic community is implementing an open networking system which, although there is still much work to be done, already works. The following benefits are starting to accrue: flexibility in choice of new systems (because customers are not tied to one manufacturer); flexibility in assigning users to systems; reduced requirements for applications software by moving users, not software; effecting economies and bringing a versatile terminal closer to the user by divorcing terminals from systems; removal of media translation problems (file transfers over the network replace costly extra peripherals); improved human communications through electronic mail. There are of course several problems associated with the approach. The lack of firm international standards has forced the community to develop much of its own software with the corresponding costs, long lead times and heavy support requirements. The evolution of protocol standards means that this commitment will continue for some time. How to ensure protocol conformance is also a problem which seems a long way from solution. - 245 - The fluidity in the Local Area Network scene has also been a cause for concern with user expectations far in advance of standards and products. The separation of the user's terminal from the computer by the network is also causing difficulties, particularly with some Digital systems where single character input with echoing by the host is essential. However, despite these problems, we feel that essentially the right decisions have been made and that the UK academic community is now moving into the new era of "téléinformatique" with much of the ground work done. 7. INTERNATIONAL COMMUNICATIONS Public X25 networks are now becoming available in many countries: an indication of those accessible from the UK is given in table 1. Many of these networks are interconnected to provide an international packet- switched service. This means that it is now practicable for computers in different countries to communicate through the medium of an X25 call. The general acceptance of the X3/X28/X29 protocol means that many hosts will also offer a useful end-user service for terminal access. Slight incompatibilities between the interpretaions of X3/X28/X29 may however degrade the quality of the user interface offered.