- Email: [email protected]
Joint academic network (JANET)
101
Network Management
Joint Academic Network (JANEq I.L. SMITH c/o Rutherford Appleton Laboratory, Chilton, Didcot, Oxon. United Kingdom 0 X l l OQX (Tel.: + 44 235 446781; E-mail." [email protected])
The article describes the funding, management and operation of the U.K. Academic Network JANET. It deals with the division of responsibility for various aspects of the service and highlights the mechanisms put in place to enable its users to participate in the management process. Access to other networks is also dealt with in brief detail Keywords: CCITT X.25, Network Management, Network Operations, Fault Reporting, Gateways, Performance Monitoring.
laa Smith is a graduate of the University of Glasgow, where he obtained a B.Sc. with Honours in Natural Philosophy (Physics) in 1963 and a Ph.D. ~ in the same subject in 1966. After a short period as a Research Assistant at Glasgow, he moved in 1968 to Daresbury Laboratory where he worked on the production of a film measurement system. In 1971 he was seconded to CERN to work on one of the first experiments to use the Omega Spectrometer and subsequently returned to Daresbury in 1973 to work on the data analysis for that experiment. He joined a group working on the development of packet switches in 1975 and then became responsible for network support in 1978. In 1983 he moved to Rutherford Appleton Laboratory to take charge of the group setting up the Joint Academic Network, and has managed the Network ever since its inception. North-Holland Computer Networks and ISDN Systems 16 (1988/89) 101-105
1. Introduction The UK Joint Academic Network (JANET) c a m e i n t o b e i n g o n the 1st A p r i l 1984 a n d represented the c o m i n g t o g e t h e r of the N e t w o r k i n g interests o f several o r g a n i s a t i o n s w i t h i n the U n i t e d Kingdom which had previously developed indep e n d e n t n e t w o r k i n g facilities for their users. T h e b a s i c a i m of the N e t w o r k is to p r o v i d e a communications infrastructure based on common s t a n d a r d s for its users. It is f u n d e d b y a n d receives p o l i c y d i r e c t i o n f r o m the D e p a r t m e n t of E d u c a t i o n a n d Science o n advice f r o m the C o m p u t e r B o a r d for U n i v e r s i t i e s a n d R e s e a r c h C o u n cils. Its m a i n c u s t o m e r s are the Universities, the R e s e a r c h C o u n c i l s a n d the Polytechnics, a l t h o u g h it is p o s s i b l e to p r o v i d e c o n n e c t i o n s to o t h e r o r g a n i s a t i o n s where it c a n b e shown that such c o n n e c t i o n s w o u l d b e n e f i t the w o r k of the D e p a r t m e n t of E d u c a t i o n a n d Science. T h e N e t w o r k is b a s e d on the X.25(1980) stand a r d s issued b y C C I T T [1]. A t the higher layers it is c u r r e n t l y utilising the so-called C o l o u r e d Book P r o t o c o l s [2]-[7] b u t h a s an i n t e n t i o n to m a k e t r a n s i t i o n to the c o r r e s p o n d i n g I S O s t a n d a r d s [8] w h e n stable i m p l e m e n t a t i o n s of these are available. T h e p u r p o s e of this p a p e r is to d e s c r i b e the o r g a n i s a t i o n a n d o p e r a t i o n of the p h y s i c a l netw o r k a n d of a t t a c h e d c e n t r a l l y m a n a g e d value a d d e d services.
2. Management Structures T h e C o m p u t e r B o a r d has d e l e g a t e d d e t a i l e d oversight of the n e t w o r k i n g activities to the N e t work Advisory Committee (NAC) which normally meets three times p e r year. T h e C h a i r m a n of this b o d y is a p p o i n t e d b y the C o m p u t e r B o a r d f r o m a m o n g s t its m e m b e r s a n d a further o n e or two
0169-7552/88/$3.50 © 1988, Elsevier Science Publishers B.V. (North-Holland)
102
LL. Smith / J A N E T
members of the Board would also be members of the NAC. In addition a seat on the NAC is available to each of the Research Councils and to the Polytechnic Community and, most importantly, to the Chairman of the National User Group, whose activities will be described later. The Executive arm of the networking activity is under the control of the Director Networking who reports directly to the Advisory Committee and he has available to him up to fourteen professional staff, divided into four groups, and three secretarial/support staff. Three of the groups together form the Joint Network Team and their work is outside the scope of this article. The fourth is the Network Executive (team of up to five people) whose primary responsibility is for the operation of the basic bearer network, JANET.
f
3. Network Topology Fig. 1. Current JANET topology.
JANET currently serves about 120 sites distributed throughout the United Kingdom of Great Britain and Northern Ireland. Although there is a tendency for sites to be considered in the areas of high population, supported sites are to be found in most areas except for the extreme northern part of Scotland. The Network consists of 8 switches (whose location owes something to the past history of networking in the community as well as to geographical considerations), interswitch trunk links and access links to the participating sites (see Fig. 1). The switching centres are located at the University of Manchester Regional Computer Centre, the University of London Computer Centre, Rutherford Appleton Laboratory, Daresbury Laboratory, the University of Edinburgh, Queens University Belfast, University of Cambridge and the University of Bath. (The first three are national computer centres operating supercomputing facilities.) All switches have been located in a computing centre, some of whose staff are already involved in providing a local area network service for the site. The switches are based on GEC 4000 series computers and they are capable of switching up to 1000 packets per second. Trunk lines are provided on digital circuits at either 256 kbps or 48 kbps with the exception of links to the Queens University Belfast, which is still served by 9.6 kbps analogue circuits. Access to sites is provided at a
variety of speeds ranging from 64 kbps to 9.6 kbps or even less. The responsibility of the J A N E T organisation terminates at the entrance to the site; i.e. the local modem or digital controller is the responsibility of JANET, the remainder of the equipment and services on a site the responsibility of the local site management. In general what is attached on site is a local area network and the user services--hosts, PADs are connected to this local area network rather than directly to JANET, although there are one or two exceptions to this general rule. The majority of sites have only a single connection to the Network, but there are a few sites which, for loading or reliability reasons, have been allowed an ancillary link.
4. Division of Responsibility 4.1. Network Executive
The Network Executive provides the central management function for the Network. It is responsible for the preparation and management of the Network's budget, planning, coordination of user support activities and reporting. It also provides a final point of arbitration in the resolution of disputes about faults.
LL. Smith / J A N E T
4.2. Network Operations Centres (NOCs) As previously mentioned, there are 8 switches serving J A N E T and at each site dealing with a switch there is located an Operations Centre. The average manpower available to the Network Executive is two man years per year per site. In general the effort provided is spread over a number of staff who divide their time between work for the Network Executive and other site-specific functions. The NOCs are responsible for the day to day operation of JANET. They are responsible for the operation of the switch on their site together with the access lines radiation from that switch and they share with other N O C s the responsibility for the operation of the trunk network. Apart from the normal array of bit error rate testers, protocol analysers, etc., the N O C s has been provided with a status alarm system based on a microcomputer, which combines the function of acting as a consul for the packet switch with interpreting the streams of status reports coming from the switch and presenting them to the operators in a user-friendly manner. This involves the use of character displays with colour presentation to indicate the current state of a circuit: green for functioning, red for broken, and yellow if error thresholds are being exceeded. Each N O C is expected to provide cover between the hours of 0830 and 1700 on each working day. In practice the majority of sites provide a more extended cover, and, in particular, because some of the sites have computer operators in attendance 24 hours day, 7 days a week they are able to provide a telephone answering service round the clock. N O C staff, although not present in the building during silent hours, are frequently on call either b y the computer operators on their own site or from the central Coordination Centre.
4. 3. Network Coordination Centre The primary function of the Network Coordination Centre is to provide the essential 24 hours a day, 7 day a week reporting service. The Centre provides a telephone number to which faults can be reported if it is not possible to contact one of the other seven N O C s and is located at the Rutherford. Appleton Laboratory. When Network specialists are not available on site, it is manned
103
by operators of the Central Computing facility, who are able to initiate call out if, after running predefined tests, they are reasonably certain that there is a problem at a remote NOC. Staff at the Central Coordination Centre also assist the Network Executive in routine tasks such as the production of new systems for the switches, and are further responsible for the control of the 2 M b p s multiplexing system which is used to derive the 256 kbps circuits used on some parts of the network.
5. Fault Reporting Because of the structure of the Network, consisting as it does predominantly of local area networks attached to a central wide area backbone, the normal procedure for fault reporting is that a user, on discovering a problem, should first of all report that problem to a designated representative on his site. Only if the site representative identifies the problem as being off-campus would the fault be reported to the nearest NOC; i.e. that Centre to which the site is directly connected. Responsibility for tracking of the fault, for ensuring its resolution and for reporting back to the caller rests with that N O C even if it has to invoke the assistance of another J A N E T N O C in order to resolve the problem. In the course of the fault resolution it m a y be necessary for some external service supplier to be contacted. This is the responsibility of the J A N E T N O C to which the external service is attached. As soon as a J A N E T N O C has identified that there is a problem it raises a fault report. This is done on a standard form on which must be recorded particulars of the caller and his site and the detailed description of the fault and the way in which it was resolved. A history of actions taken is recorded in case there is a prolonged outage or a difficulty in resolving the particular problem. Faults which remain unresolved for more than a day would be reported to the Network Executive.
6. Performance Monitoring Statistical information about traffic levels, fault levels, etc. on each circuit together with information about performance of the switch itself are
104
LL. Smith /JANET
recorded by each packet switch exchange. These are collected automatically twice a week over the Network and processed to produce statistical reports, traffic flow diagrams availability and MTBF figures, etc. These reports are reviewed periodically to ensure that components of the Network are not becoming overloaded or malfunctioning. Where it was clear that a particular component of the Network was overloaded, the Network Executive, with interested parties, would plan for an upgrade of the facilities provided that finance was available. The target MTBF of 2000 hours for each switch has not, unfortunately, been achieved, but average availability of greater than 99.8% has been achieved. The above-mentioned analysis is primarily concerned with average performance of the Network, but it is also necessary to study the peak performance capabilities, particularly for terminal activity where response rather than throughput is the important criteria. To this end a response monitoting system has been developed based on a microcomputer. This is connected to a packet assembler/disassembler and sends periodic messages to designated echo points on the Network and measures round trip delay. If these tests indicate significant delays are occurring, the Executive would hope to take action to rectify this situation. A number of experiments have also been conducted into performance of file transfer over the Network and it has been shown that significant throughput can be achieved, even on a many hop call, provided the packet size and window parameters can be satisfactorily negotiated. A total throughput exceeding half the speed of the slowest fine in the path has been achieved even for a seven hop connection.
7. User Representation Right from the start it was considered vital that the users of the Network should have a voice on the Network Advisory Committee i.e. that there should be a clear mechanism for users to express their opinion about the performance of the Network and to be in a position to review policy and proposed enhancement programmes. To this end, a number of regional user groups have been established to which each site in the region is entitled to send two representatives. It has also
been foreseen that there may be a requirement for subject-oriented user groups to be established and given a voice in the system and this has proved to be the case with two such groups, for Nuclear Physics and the Librarians, having been estabfished. Each of the regional user groups and subject-oriented user groups is allowed to send two representatives to a National User Group, whose chairman is ex officio a member of the Network Advisory Committee. Representatives of the Network Executive and of the NOCs attend both the regional and subject-oriented groups and the National User Group to provide firsthand input on operational aspects to these groups. The Director, Networking also attends the National User Group to provide input on policy matters.
8. Value Added Network Service The Network also supports a number of value added services which can be divided into two broad classes, namely internal facilities and those associated with providing access to other Networks. 8.1. Internal Services Name Registration Facility This is a central database on which directory information is maintained to provide a name to address translation for services on the Network. It is organised on a site by site basis and each site has a designated administrator who is responsible for keeping information about machines on that site up to date. Copies of the database can then be pulled off and made available to hosts on the Network. It is anticipated that the size of this directory will grow considerably in the next few years, although it is not clear yet whether it will be possible to maintain a complete list of all systems down to the workstation or even to the microcomputer level. News Facility This facility was initially aimed at providing information about the Network itself to users, but it has evolved as time passed to become an initial attempt at a central information service for the Network. A number of limitations have been identified and it is hoped that the lessons gained with
LL. Smith / J A N E T
this service and with other similar services on sites, and with insight into what other Networks have been able to achieve, will help in the design and implementation of a more satisfactory service in the near future. This is one of the areas in which the National User Group is likely to play a prominent part. 8.2. Gateways to External Networks It is currently possible from J A N E T to access the Public Packet Switched Data Network; EARN, the European Academic Research Network; EUnet, the European Arm of the U S E N E T activity; and the ARPA Internet. In addition, a new facility has been established which uses an early implementation of the X.400 mail standard, as produced by the University of British Colombia [9], on one side, and J A N E T Mail [7] on the other, and is being utilised in the pilot message handling system experiment which involves a number of other European countries, Canada and several nations in the Far East. The EARN, EUnet and ARPA gateways were initially established independently of the central network organisation but it has become clear in the last couple of years that it would be sensible to have a more centralised coordination of these activities. The pulling together of these resources is now well under way with the ultimate aim of providing a uniform user interface for access to all facilities. Ideally it should not be necessary for a user to know which gateway he is using, but simply to specify which target system he wishes to interact with and for the Network to take care of the routing for him. It is clear that an authentication, authorisation and accounting mechanism will have to be built into this system, but this is still a matter for debate at the present time.
9. Conclusion By providing a central funding mechanism and by a central coordination, it has been possible for
105
the U K Academic Community to build a general purpose computer network with good connectivity and reasonable performance. Procedures have been implemented to ensure a systematic response to fault situations and to enable users of the network to have a voice in the way in which the Network is operated and expansion planned. From this sound platform it is anticipated that the Network can continue to evolve to meet the new and challenging demands likely to be placed upon by its users in the next few years. It is also in a strong position to establish better links with other networks in the UK, in Europe and the USA (indeed in all parts of the world) in response to clear requirements from the users to so do.
References [1] CCITI', Data Communication Networks, Services and Facilities, Terminal Equipment and Interfaces Recommendation X.25, 1980. [2] A Network Independent Transport Service, SG3/CP(80)2, Study Group 3 of British Telecom PSS User Forum, 1980. [3] Character Terminal Protocols on PSS (Revision 1), SG3/CP(81)6, Study Group 3 of British Telecom PSS User Forum, 1981. [4] Simple Screen Management Protocol, JNT, 1985. [5] A. Network Independent File Transfer Protocol, FTP-B(80), High Level Protocol Group, as revised by the File Transfer Protocol Implementors' Group of the Data Communication Protocols Unit, 1981. [6] A Network Independent Job Transfer and Manipulation Protocol, DCPU/JTMP(81), The JTMP Working Party of the Data Communications Protocols Unit, 1981. [7] S.E. Kille, JNT Mail Protocol (Revision 1), Department of Computer Science, University College, London, 1984. [8] Transition to OSI Standards, Final Report of the Academic Community OSI Transition Group, 1987. [9] G. Neufeld, J. Demco, B. Hilpert and R. Sample, EAN: An X.400 Message System, Proc. 2nd International Symposium on Computer Message Systems, IFIP, Washington, DC (1985). References [2]-[8] are available from JNT, c / o Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire O X l l 0QX, United Kingdom.
Network Management
Joint Academic Network (JANEq I.L. SMITH c/o Rutherford Appleton Laboratory, Chilton, Didcot, Oxon. United Kingdom 0 X l l OQX (Tel.: + 44 235 446781; E-mail." [email protected])
The article describes the funding, management and operation of the U.K. Academic Network JANET. It deals with the division of responsibility for various aspects of the service and highlights the mechanisms put in place to enable its users to participate in the management process. Access to other networks is also dealt with in brief detail Keywords: CCITT X.25, Network Management, Network Operations, Fault Reporting, Gateways, Performance Monitoring.
laa Smith is a graduate of the University of Glasgow, where he obtained a B.Sc. with Honours in Natural Philosophy (Physics) in 1963 and a Ph.D. ~ in the same subject in 1966. After a short period as a Research Assistant at Glasgow, he moved in 1968 to Daresbury Laboratory where he worked on the production of a film measurement system. In 1971 he was seconded to CERN to work on one of the first experiments to use the Omega Spectrometer and subsequently returned to Daresbury in 1973 to work on the data analysis for that experiment. He joined a group working on the development of packet switches in 1975 and then became responsible for network support in 1978. In 1983 he moved to Rutherford Appleton Laboratory to take charge of the group setting up the Joint Academic Network, and has managed the Network ever since its inception. North-Holland Computer Networks and ISDN Systems 16 (1988/89) 101-105
1. Introduction The UK Joint Academic Network (JANET) c a m e i n t o b e i n g o n the 1st A p r i l 1984 a n d represented the c o m i n g t o g e t h e r of the N e t w o r k i n g interests o f several o r g a n i s a t i o n s w i t h i n the U n i t e d Kingdom which had previously developed indep e n d e n t n e t w o r k i n g facilities for their users. T h e b a s i c a i m of the N e t w o r k is to p r o v i d e a communications infrastructure based on common s t a n d a r d s for its users. It is f u n d e d b y a n d receives p o l i c y d i r e c t i o n f r o m the D e p a r t m e n t of E d u c a t i o n a n d Science o n advice f r o m the C o m p u t e r B o a r d for U n i v e r s i t i e s a n d R e s e a r c h C o u n cils. Its m a i n c u s t o m e r s are the Universities, the R e s e a r c h C o u n c i l s a n d the Polytechnics, a l t h o u g h it is p o s s i b l e to p r o v i d e c o n n e c t i o n s to o t h e r o r g a n i s a t i o n s where it c a n b e shown that such c o n n e c t i o n s w o u l d b e n e f i t the w o r k of the D e p a r t m e n t of E d u c a t i o n a n d Science. T h e N e t w o r k is b a s e d on the X.25(1980) stand a r d s issued b y C C I T T [1]. A t the higher layers it is c u r r e n t l y utilising the so-called C o l o u r e d Book P r o t o c o l s [2]-[7] b u t h a s an i n t e n t i o n to m a k e t r a n s i t i o n to the c o r r e s p o n d i n g I S O s t a n d a r d s [8] w h e n stable i m p l e m e n t a t i o n s of these are available. T h e p u r p o s e of this p a p e r is to d e s c r i b e the o r g a n i s a t i o n a n d o p e r a t i o n of the p h y s i c a l netw o r k a n d of a t t a c h e d c e n t r a l l y m a n a g e d value a d d e d services.
2. Management Structures T h e C o m p u t e r B o a r d has d e l e g a t e d d e t a i l e d oversight of the n e t w o r k i n g activities to the N e t work Advisory Committee (NAC) which normally meets three times p e r year. T h e C h a i r m a n of this b o d y is a p p o i n t e d b y the C o m p u t e r B o a r d f r o m a m o n g s t its m e m b e r s a n d a further o n e or two
0169-7552/88/$3.50 © 1988, Elsevier Science Publishers B.V. (North-Holland)
102
LL. Smith / J A N E T
members of the Board would also be members of the NAC. In addition a seat on the NAC is available to each of the Research Councils and to the Polytechnic Community and, most importantly, to the Chairman of the National User Group, whose activities will be described later. The Executive arm of the networking activity is under the control of the Director Networking who reports directly to the Advisory Committee and he has available to him up to fourteen professional staff, divided into four groups, and three secretarial/support staff. Three of the groups together form the Joint Network Team and their work is outside the scope of this article. The fourth is the Network Executive (team of up to five people) whose primary responsibility is for the operation of the basic bearer network, JANET.
f
3. Network Topology Fig. 1. Current JANET topology.
JANET currently serves about 120 sites distributed throughout the United Kingdom of Great Britain and Northern Ireland. Although there is a tendency for sites to be considered in the areas of high population, supported sites are to be found in most areas except for the extreme northern part of Scotland. The Network consists of 8 switches (whose location owes something to the past history of networking in the community as well as to geographical considerations), interswitch trunk links and access links to the participating sites (see Fig. 1). The switching centres are located at the University of Manchester Regional Computer Centre, the University of London Computer Centre, Rutherford Appleton Laboratory, Daresbury Laboratory, the University of Edinburgh, Queens University Belfast, University of Cambridge and the University of Bath. (The first three are national computer centres operating supercomputing facilities.) All switches have been located in a computing centre, some of whose staff are already involved in providing a local area network service for the site. The switches are based on GEC 4000 series computers and they are capable of switching up to 1000 packets per second. Trunk lines are provided on digital circuits at either 256 kbps or 48 kbps with the exception of links to the Queens University Belfast, which is still served by 9.6 kbps analogue circuits. Access to sites is provided at a
variety of speeds ranging from 64 kbps to 9.6 kbps or even less. The responsibility of the J A N E T organisation terminates at the entrance to the site; i.e. the local modem or digital controller is the responsibility of JANET, the remainder of the equipment and services on a site the responsibility of the local site management. In general what is attached on site is a local area network and the user services--hosts, PADs are connected to this local area network rather than directly to JANET, although there are one or two exceptions to this general rule. The majority of sites have only a single connection to the Network, but there are a few sites which, for loading or reliability reasons, have been allowed an ancillary link.
4. Division of Responsibility 4.1. Network Executive
The Network Executive provides the central management function for the Network. It is responsible for the preparation and management of the Network's budget, planning, coordination of user support activities and reporting. It also provides a final point of arbitration in the resolution of disputes about faults.
LL. Smith / J A N E T
4.2. Network Operations Centres (NOCs) As previously mentioned, there are 8 switches serving J A N E T and at each site dealing with a switch there is located an Operations Centre. The average manpower available to the Network Executive is two man years per year per site. In general the effort provided is spread over a number of staff who divide their time between work for the Network Executive and other site-specific functions. The NOCs are responsible for the day to day operation of JANET. They are responsible for the operation of the switch on their site together with the access lines radiation from that switch and they share with other N O C s the responsibility for the operation of the trunk network. Apart from the normal array of bit error rate testers, protocol analysers, etc., the N O C s has been provided with a status alarm system based on a microcomputer, which combines the function of acting as a consul for the packet switch with interpreting the streams of status reports coming from the switch and presenting them to the operators in a user-friendly manner. This involves the use of character displays with colour presentation to indicate the current state of a circuit: green for functioning, red for broken, and yellow if error thresholds are being exceeded. Each N O C is expected to provide cover between the hours of 0830 and 1700 on each working day. In practice the majority of sites provide a more extended cover, and, in particular, because some of the sites have computer operators in attendance 24 hours day, 7 days a week they are able to provide a telephone answering service round the clock. N O C staff, although not present in the building during silent hours, are frequently on call either b y the computer operators on their own site or from the central Coordination Centre.
4. 3. Network Coordination Centre The primary function of the Network Coordination Centre is to provide the essential 24 hours a day, 7 day a week reporting service. The Centre provides a telephone number to which faults can be reported if it is not possible to contact one of the other seven N O C s and is located at the Rutherford. Appleton Laboratory. When Network specialists are not available on site, it is manned
103
by operators of the Central Computing facility, who are able to initiate call out if, after running predefined tests, they are reasonably certain that there is a problem at a remote NOC. Staff at the Central Coordination Centre also assist the Network Executive in routine tasks such as the production of new systems for the switches, and are further responsible for the control of the 2 M b p s multiplexing system which is used to derive the 256 kbps circuits used on some parts of the network.
5. Fault Reporting Because of the structure of the Network, consisting as it does predominantly of local area networks attached to a central wide area backbone, the normal procedure for fault reporting is that a user, on discovering a problem, should first of all report that problem to a designated representative on his site. Only if the site representative identifies the problem as being off-campus would the fault be reported to the nearest NOC; i.e. that Centre to which the site is directly connected. Responsibility for tracking of the fault, for ensuring its resolution and for reporting back to the caller rests with that N O C even if it has to invoke the assistance of another J A N E T N O C in order to resolve the problem. In the course of the fault resolution it m a y be necessary for some external service supplier to be contacted. This is the responsibility of the J A N E T N O C to which the external service is attached. As soon as a J A N E T N O C has identified that there is a problem it raises a fault report. This is done on a standard form on which must be recorded particulars of the caller and his site and the detailed description of the fault and the way in which it was resolved. A history of actions taken is recorded in case there is a prolonged outage or a difficulty in resolving the particular problem. Faults which remain unresolved for more than a day would be reported to the Network Executive.
6. Performance Monitoring Statistical information about traffic levels, fault levels, etc. on each circuit together with information about performance of the switch itself are
104
LL. Smith /JANET
recorded by each packet switch exchange. These are collected automatically twice a week over the Network and processed to produce statistical reports, traffic flow diagrams availability and MTBF figures, etc. These reports are reviewed periodically to ensure that components of the Network are not becoming overloaded or malfunctioning. Where it was clear that a particular component of the Network was overloaded, the Network Executive, with interested parties, would plan for an upgrade of the facilities provided that finance was available. The target MTBF of 2000 hours for each switch has not, unfortunately, been achieved, but average availability of greater than 99.8% has been achieved. The above-mentioned analysis is primarily concerned with average performance of the Network, but it is also necessary to study the peak performance capabilities, particularly for terminal activity where response rather than throughput is the important criteria. To this end a response monitoting system has been developed based on a microcomputer. This is connected to a packet assembler/disassembler and sends periodic messages to designated echo points on the Network and measures round trip delay. If these tests indicate significant delays are occurring, the Executive would hope to take action to rectify this situation. A number of experiments have also been conducted into performance of file transfer over the Network and it has been shown that significant throughput can be achieved, even on a many hop call, provided the packet size and window parameters can be satisfactorily negotiated. A total throughput exceeding half the speed of the slowest fine in the path has been achieved even for a seven hop connection.
7. User Representation Right from the start it was considered vital that the users of the Network should have a voice on the Network Advisory Committee i.e. that there should be a clear mechanism for users to express their opinion about the performance of the Network and to be in a position to review policy and proposed enhancement programmes. To this end, a number of regional user groups have been established to which each site in the region is entitled to send two representatives. It has also
been foreseen that there may be a requirement for subject-oriented user groups to be established and given a voice in the system and this has proved to be the case with two such groups, for Nuclear Physics and the Librarians, having been estabfished. Each of the regional user groups and subject-oriented user groups is allowed to send two representatives to a National User Group, whose chairman is ex officio a member of the Network Advisory Committee. Representatives of the Network Executive and of the NOCs attend both the regional and subject-oriented groups and the National User Group to provide firsthand input on operational aspects to these groups. The Director, Networking also attends the National User Group to provide input on policy matters.
8. Value Added Network Service The Network also supports a number of value added services which can be divided into two broad classes, namely internal facilities and those associated with providing access to other Networks. 8.1. Internal Services Name Registration Facility This is a central database on which directory information is maintained to provide a name to address translation for services on the Network. It is organised on a site by site basis and each site has a designated administrator who is responsible for keeping information about machines on that site up to date. Copies of the database can then be pulled off and made available to hosts on the Network. It is anticipated that the size of this directory will grow considerably in the next few years, although it is not clear yet whether it will be possible to maintain a complete list of all systems down to the workstation or even to the microcomputer level. News Facility This facility was initially aimed at providing information about the Network itself to users, but it has evolved as time passed to become an initial attempt at a central information service for the Network. A number of limitations have been identified and it is hoped that the lessons gained with
LL. Smith / J A N E T
this service and with other similar services on sites, and with insight into what other Networks have been able to achieve, will help in the design and implementation of a more satisfactory service in the near future. This is one of the areas in which the National User Group is likely to play a prominent part. 8.2. Gateways to External Networks It is currently possible from J A N E T to access the Public Packet Switched Data Network; EARN, the European Academic Research Network; EUnet, the European Arm of the U S E N E T activity; and the ARPA Internet. In addition, a new facility has been established which uses an early implementation of the X.400 mail standard, as produced by the University of British Colombia [9], on one side, and J A N E T Mail [7] on the other, and is being utilised in the pilot message handling system experiment which involves a number of other European countries, Canada and several nations in the Far East. The EARN, EUnet and ARPA gateways were initially established independently of the central network organisation but it has become clear in the last couple of years that it would be sensible to have a more centralised coordination of these activities. The pulling together of these resources is now well under way with the ultimate aim of providing a uniform user interface for access to all facilities. Ideally it should not be necessary for a user to know which gateway he is using, but simply to specify which target system he wishes to interact with and for the Network to take care of the routing for him. It is clear that an authentication, authorisation and accounting mechanism will have to be built into this system, but this is still a matter for debate at the present time.
9. Conclusion By providing a central funding mechanism and by a central coordination, it has been possible for
105
the U K Academic Community to build a general purpose computer network with good connectivity and reasonable performance. Procedures have been implemented to ensure a systematic response to fault situations and to enable users of the network to have a voice in the way in which the Network is operated and expansion planned. From this sound platform it is anticipated that the Network can continue to evolve to meet the new and challenging demands likely to be placed upon by its users in the next few years. It is also in a strong position to establish better links with other networks in the UK, in Europe and the USA (indeed in all parts of the world) in response to clear requirements from the users to so do.
References [1] CCITI', Data Communication Networks, Services and Facilities, Terminal Equipment and Interfaces Recommendation X.25, 1980. [2] A Network Independent Transport Service, SG3/CP(80)2, Study Group 3 of British Telecom PSS User Forum, 1980. [3] Character Terminal Protocols on PSS (Revision 1), SG3/CP(81)6, Study Group 3 of British Telecom PSS User Forum, 1981. [4] Simple Screen Management Protocol, JNT, 1985. [5] A. Network Independent File Transfer Protocol, FTP-B(80), High Level Protocol Group, as revised by the File Transfer Protocol Implementors' Group of the Data Communication Protocols Unit, 1981. [6] A Network Independent Job Transfer and Manipulation Protocol, DCPU/JTMP(81), The JTMP Working Party of the Data Communications Protocols Unit, 1981. [7] S.E. Kille, JNT Mail Protocol (Revision 1), Department of Computer Science, University College, London, 1984. [8] Transition to OSI Standards, Final Report of the Academic Community OSI Transition Group, 1987. [9] G. Neufeld, J. Demco, B. Hilpert and R. Sample, EAN: An X.400 Message System, Proc. 2nd International Symposium on Computer Message Systems, IFIP, Washington, DC (1985). References [2]-[8] are available from JNT, c / o Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire O X l l 0QX, United Kingdom.