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FJECNPADISISCHlSC5.1E
E/ECA/PADIS/SCH/SCS.1E·
FOREWORD
Thisdocumentwas developed by the PanAfrican Development Information System(pADIS) of the United Nations Economic Commission for Africa(ECA) in theframework of the workof the Standardization Subcommittee no. 5: Computer networking, E-mail and On-line access supported by the Carnegie Corporation of New York.
The list of PADTS Standardization Subcommittees is as follows:
Subcommittee 1: PADIS Manual for document analysis.
Subcommittee 2; Selection and evaluation ofcriteriaoftextualdata baseprograms
Subcommittee 3: Evaluation of textual data base formats and structures
Subcommittee 4: Selection and acquisition of microcomputerhardware configurations
Subcommittee 5: Computer networking, e-mail and on-line access
Subcommittee6: Authorityfiles
Subcommittee 7: CD ROMdevelopment
ECDllomic Commission for Africa Moren1997
P. O. Box 3001 AddisAbaba. Ethiopia Tel:(251)I 511167
1. INTRODUCTION
With the growing penetration of computer technology in institutions across Africa, decision makers are being faced with an expanding rangeof choices for their informatior, processing needs. However, African information management centers facemany problems in identifying the necessary hardware and software suitable for their information processing activity.
Some of the problems they face are:
_ The scarcity of information on Information Technology as a result ofthe lack of a national policy and instruments to help them select thenecessary hardware and software
- The lack of journals and magazines on Information Technology available to African information centers
- TI\elack of guidelines on standard hardware configuration required for diverse operational activities
- The large variety andchoices of hardware on the market
- Donor institutionswhich tendtoimposehardware equipment on recipient institutions with little regard for the technical choices at hand
During thelastfewyears, computer networkingbothat the institutional level(Local Area Networks - LANs) and Wide Area Network (WAN) links to other local and international networks have been set up independently in a large number of African countries. With the proliferation of diverse links between organisations locally and internationally, several standardization issues have emerged.
Theseaffect all forms of transmission media - from diskette, to public switched data net works, .. well as the formats of the data which are carried over the networks for the great variety of applications in use. Different hardware, peripherals, configurations, application protocols and transmission media have been used to network computers. Appropriate
E/ECA/PADIS/SCH/SC5.1E also scarce. In addition, the unplanned emergence of many communications networks has meant that there is a lack of standard addressing techniques for interconnectivity between systems, bothnational!yand international1y.
Some of the current problemsinelectronic information exchange arise from the variety of software ("mailers" and other communication packages), different protocols (Zmodem, UUCP, TCP/IP), and different networking techniques (Fido, UUCP, Internet, X.4(0) as well as several forms of transmission media(IDD/SDD, X.2S, leased lines, HF packetradio, UHF LEO satellites etc.). 10 addition, there is a growing variety of hard storage media such as 2MB diskettes, 128MB cartridges, CD-ROM and DAT.
This report aims to clarify the variety of options availableso thatthe mostappropriate choices can bemadein using computer technology in today's African environment. It also aims to provide an indication of some of the standards thatshouldbe metin purchasing from suppliersor indrowing up donor agreements.
2. THE BACKGROUND '1'0 TECHNOLOGY CHOICES FOR NB'lWOlUCINQ
2.1 Networking Growth
As computers have gained widespread penetration in organisations, it has become increasingly apparent that the use of standalone functions can begreatly enhanced through efficient networking and information. sharing. Aside from wider access to scarce resources such as lazer printers and large hard disk storage, the ability to
easily
communicate documents,.messages, spreadsheetsanddatabasescangreatly
improve theeffectivenessofany organisation workingwithinformation. Withtheemergenceoflowcost international networks ' it is now possibletocommunicate daily with others around the world at almostinsignjficant cost.Increasinglytheindividual PC is now being seen as simply a single workstation withina wideor local area network. As a result, connectivity between computers has become a primary issueinanyinformationsystemdevelopmentpIan.Inmanycases it is now expected that every computer should be '01\ thenett in some way and beabletocommunicate withanyother computer similarly connected, beit inthe same office, or on anothercontinent. In this respect, _ theInternethasemerged as the general trunking system betweenall networks, with itsTCP/IP protocols as the de-facto standard for obtaining full connectivity to the global network.
Although X.400 has been talked about for many yearsas the emerging OSI standard for communications, ithasnot enjoyed the support that was expected of it. Being a very feature..
full standard requiring substantial computer resources and technical expertise to operate, X.400hasbeeninstalled mainlybya few large organisations and PTTs. There are a number ofgateways between InternetsystemsandX.400 systemsand these are generally transparent to the user.
2.2 Rlg-b Bat•• of Change iD COJII;puter Technology
The demand for communication facilities, coupled with the generally high rate of teChnological developmentinthecomputerfieldhasresultedinthe growth of ahuge rangeof networking productsand solutions. In such a new and rapidly evolving field, the solutions chosen could be outdated by the time they are implemented unless there is a clear understanding ofhowinformation systems aredeveloping. In addition, most organisations will inevitably be faced with having to maintainearly andlate model hardware, only some of whichmaybeable to operatethe latestsoftware.
Fortunately generallyaccepted standards havebegun to emerge in manyareas, makingit more possible than it has been in the past to conserve investments in resources- as an organisationls information systemsgrowand develop. Nevertheless, tocope withtheongoing change and turnover in staff, investment in training has become a more important and permanent partof organisation budgets.
E/ECA/PADI 5/ SCH/ SC5. 1£:
2.3 DevelODments in User Interfaces and Computer Software
Applications are becoming much more uniform intheir interfaces, with the widespread adoption of the Microsoft Windows and Apple Macintosh systems. Emulating the success of the Apple Macintosh userenvironment, Windowsprogrammes all use similar 'point&click' menu systems and data manipulation methods. Thisoffers a reduced learningcurve for users running a variety of programmes but is causing additional demand for 'high-endI systems with
enoughcomputing resources tohandle the additional overhead of the graphic environment and heavy memory requirement of the new packages. Market forces can tend to overemphasise the benefitsof the Graphical User Interface (GU[) whena simple Character-based User Interface (CUI) can be more efficient for many keyboard intensiveprocesses (word processing, data entry etc.), especially on slower, 'low-end' computers.
For all ranges of machines andcommon operating systems however, there isanincreasing quantity of high qualityshareware or public domain software being developed, primarilyat researchand academic institutions in the US and Europe. Involved with electronic information networking and sharing for decades, organisations such as the National Centre for Supercomputing Applications (NCSA) have developed highly sophisticated tools such as Mosaic (a multimedia hypertext based interface to distribute information sources on the Internet). Since freeand shareware software can have avery fast distribution and debugging cycle (especially in a highly networked environment) a large number of programmes have reachedsufficient maturity to form the basis for a complete low cost network where software purchases need form little partof the networkingbudget.
3 _ NE'l'WORKING SERVICES
The ability to send messagesanddocuments between computers, of~en called electronic mail, or email, is frequently seen as the baselinecommunications service requirement for electronic networking systems. Of course permanently connected computers are expected to be able to share applications, peripherals and large data sets, but electronic mail forms a
common denominator between local and wide area networks of all types world wide. In particular, email using standard voice grade dialup phone lines is an ideal tool for enhancing communications in Africa. It is a far cheaper and more convenient technology than facsimile or telexwherevera computer andtelephone line areavailable. Furthersavings in time and cost are available from electronic mail because the medium is not limited to one-to-one communication with another individual, but can also be used to broadcast information to groups of .interested recipients. Up to 100 times faster than fax (see below), email reduces paperconsumption, does not require time consuming reentry of data into the computer and can be automaticallyfiled for quick referenceby keyword search.
For standalone machines, email is usually by farthe most used of all networking functions when it isavailablecheaply. Access to othershared services such as data base lookup and file storesare alsoavailableover dialup linesbut are used less often, especially when hard media transfer is readilyavailable - magnetic& optical mediaand hard copy printout.
3.1 Dialup Hosts/Nodes/Hubs
Although it ispossible for a user to send a document over dialup phone linesdirectly to the recipient's computer, in general this is expensive and inconvenient to scheduleif the transfer involves a long distance call. As a result it is cost effective for a group of users to support a local email hub whichprovidesa 24 hour service, cutting costs and providing a conveniently accessible link to the local and world-wide network ofemail users.
The userseffectively sharethe costs of apermanent leased line link to the Internet, or if this is not available, high speed modems are used to transfer batches of email between internatiosal hubs on a store and forward basis. The local host, often called a post-office, provides the connection totheInternet linked systems around the world and messages can also
be sent to outbound fax and telex servers, and to commercial hosts such as Dialcom and GeoNet.
E/ECA/PADIS/SCH!SC5.1E
3.1.1 Services Available
Through access to a local host, it is possible to gain access to the huge community of existing users online. With the global interconnection of networks users will connect 'to millions of others on the various University computer networks that form part of the Internet in Africa and worldwide, the APC, Janet, BitNet and UniNet in Southern Africa, as wellas the commercial users on other business related networks suchas CompuServe and MCI Mail.
For many purposes, sending tiles and messages directly toanother individual isall that is necessary. However, thereisalso the opportunity to'broadcast' the message to a select group of participants simply by sending one copy to a special name designated to hold the list of recipients. These canbeprivate 'mailing lists' held on the user's computer (for example a list called COLLEAGUES could bea personal list of staff members), or public lists held on all participating local hosts. The public lists are usually known as newsgroups, but they can also be called electronic conferences, echo areas, special interest groups or bulletin boards. They canbepublicly available to anyone on any of these networks, or restricted to a select group for examplea co-ordinating committee with members spread over a numberoflocal hosts.
The sender does not have to knowthe electronic address of each participant to send them each a message. Instead, a single message is sent to the newsgroup name which then passes the message on to all other recipients of the newsgroup. 1he list could also comprise an unlimited mixture of fax: numbers, telex numbers, electronic mail addresses and bulletin boards or newsgroups. Newsgroups are usuallybasedaround a particular topic and canlast for a short period or proceed for anunlimited time. They can be discussion oriented or used mainly for announcements and information postings.
Currently thereare about 5000 different topic related newsgroups knownas the UseNet that canbe made publicly availableto anyone on the various Internet networks. An even larger number of online newsgroups are circulated privately bynetworks of usersand local hosts
whichco-operatetogethertoform sub-networks over the Internet. For example organisations participatingintheAPe would have access to another 3-4000 newsgroups, New newsgroups canbestarted atanytimebya sufficiently motivated group ofusers withtheassistance of the system operator. If a particularnewsgroupis not available on the local host, there aremany email servers available on the Internet which can allow the user toparticipate in the newsgroup remotely.
Often a 'full feed'of the complete set of international newsgroups is obtained by the local host,butexpiresafter only a few days, allowinglocal users whohavea particular interestin an esoteric topic to obtain the newsgroup locally and archive it on their own equipment if
necessary. This is of course contingent on thebandwidth of theconnection to the Internet, and the growth in the number of users contributing to the global circulationof data.
In Africa particularly, the utilityof a full feed is somewhat more limited. Aside from the . high communicationcosts of obtaining so muchdata, many international newsgroupsare too Eurocentric or North America oriented (because of the high concentration of users in these countries) to be very useful. Many newsgroups also contain too much 'noise' - popular discussion topics can often havemany hundreds of new postings each day, sometimesmaking it impossible for one userto absorb allof the input, much ofwhich can be irrelevant postings from naive new users. Thisproblem shouldbereduced as the growth in the number ofnew usersslows down and the rangeand distribution ofnewsgroups diversifies.
In theinterim, user interfaces that filter the information flow for particular keywords are becomingincreasinglypopular, as are •twit filters' which allow users to set their software to ignore messages on certain subjects or from certain individuals. In addition. moderated newsgroups (where all postings are sent for review before general release) have become importantinproviding a higher 'signal-to-noise' ratio, as arelimitedcirculation of newsgroups
toparticular local hosts boundby similargeographyor other common features.
E/ECA/PADIS/SCH/SC5.1E The proceedings of the newsgroups should be storedbymost local hosts running up-to-date software, so that interested users can browse by subject, author or keyword search through the archived items for material of particular relevance, or to 'catch up' on the discussionto date.
These steadily growing information banks on a vast range of fields now form an increasingly importantdatabaseof the repository of stored knowledge available electronically. The volume ofdatathat is added to them daily on a global basis is over 200MB so a local host maykeep only full archives of the small number of newsgroups that are most relevant toits users.
In addition to archives of postings to newsgroups, local hosts may also provide accessto a range of specialised databases for their own users and for others on the Internet. Until recently most such databases were providedby commercial systems charging high prices for access. While these systems still have their value, there are increasing numbers of organisations making their databasesfreely available. Examples include the US Library of Congress bibliographic data, the IDRC's index of development projects (Index) and the European Community's ECHO data service. Aside from being made available via remote access over the Internet, (using tools such as Gopher, WWW, WArS and FTP) many are also distributed on CD-ROM, on tape, or as updates sent by electronic file transfer. Most organisations providing databases do not operate their own host to distribute the information, but usedisk space and databaseserver facilities from their local Internet host.
Using electronic mail to examine databases and document stores held elsewhere on the Internet isalso possible, but efficient use of databasesearch tools is really onlyachievableby experienced researchers with permanent access to a full Internet connection. A Ifull, Internet link is a permanent leased line connection with fixed monthly rental costs which are not proportional to the volumeof data whichpasses through thelink. Users of these systems are able tobuild up sufficient expertise with the information tools and sources available and so it is becoming increasingly common to find remote email users brokering queries through agents with better access to the skills and resources necessary to carry out the research.
Although a permanent leased linemaybeparticularly useful for interactive searching of
.-linedatabaseeanddirectaccess toothernetworks, itisnotnecessaryfor the more important email services. Nevertheless it can reduce the cost and increase the delivery speed of international email traffic, depending on the softwarechosen.
Local public access hosts are now operating in about half the African countries - see Appendix forfull list. Usersinother countries where there are no localhosts have toconnect to a systemin anothercountry, eitherbyinternational direct dial, alocal packetswitching
service, or some other means.
There are almost no public access networks in Africa operating on a national basis -i.e.
localdialaccess outsideof the capital citytoa national public access host - except forEgypt, Tunisia and South Africa. These countries are also theonly ones with public access hosts offering full Internet connectivity via permanent international leasedcircuits.
There are of course a substantial number of largecorporate and government networks, some of which are formally and informally extending services to a wider user base, suchas
theUNEP. SITA, IBM, and RIO/ORSTOM. Also, new initiatives are rapidly emerging on -thecontinent and fun Internet publicaccess linksare likelyin at least a dozen more African
countriesbymid 1995.
I
Hostsfullyconnected to the Internetusually charge a flatmonthly subscription feerangingJ
~ front US$lO to US$65permonth andpossibly anadditional hourly usage rate. The flat rate,
charging system is one of the major reasons for the popularity of the Internet as it allows
organisations to budgetaccuratelyfor theircommunicationsuse.
Hoststhatmust makeinternational callsfor connectivity, charge a small subscriptionfee and thena volume feeper
..
kilobyte transmitted, ranging from USO.Ot to USO.5Oc per kilobyte.'Therangeofcharges reflects a variety of factors such as thedegree ofdonor funded subsidies.
availabilityofvolunteer support andtechnicalstaff(perhaps funded through secondmentby
E/ECA/PADIS/SCH/SC5.1E another organisation), the costs of making international calls and the efficiency of the
rue
transfer protocols in use on intemationallinks.
In general a public access host canbeevaluated using the following criteria:
number ofusers
volume of messagetraffic
international link used: size in KBps of leased line or speed of modem and calling schedule ifthehost is using a dialupconnection
- software provided to users - range of services provided:
electronic mail, binary file attach - preferably MIME compliant - number of newsgroups/conferences available,
- fax server (local and to international faxnetwork)
- local full text databases, especially of conferences/newsgroups(WAIS server) - document and file store tools: WWW, Gopher, Archie, FTP, Veronica.
- talk/chat facility (for online conversations) - emailtools: FfPMail, Listserver, Gophermail
- range and size of information storedlocally: newsgroups, databases etc.
- costs of local, national and international traffic - user group involvement
level of institutional support level of technical support - level of financial support
- implementation of cost recovery measures
- the host system equipmentIs capacity to support additional users - availability of additional telephone linecapacity
- availability of training sessions, on-site technicalandtelephone support
- availability of information materials, user and newsgroup directories and other documentation
- accessto hardware service and maintenance - communication protocols SUpported:
- X.25
- Rlogin/Telnet
-uucs
- SLIP - PPP - FIDO
- VTlDOIDumb Terminal interactive access - MNP/V42 error correction on modems.
- quantity of hard disk storage space available for users - length oftimeinoperation
Inmost casestheindicatorsof aviable systemare:
- An experienced and motivated system operator supportedby ongoingtraining and online technicalsupport fromother system operators.
- Adequate time availablefor the host staffto conduct outreach andtraining of users Information materials forpotentialuserslsubscribers
Good host and end-usersoftware
+
documentation Availability of backup hardware and repairfacilities /\ reliable databackup scheduleAdequate telephone line availability
Ongoing infrastructural supportby the organisation hosting the node Capacity to support increased numbers of users
Low costs (less than lOe/Kilobyte) for internationalnewsgroupandmail connections Ability to log and bill for all traffic on the node.
A strong and involved user community representing a variety of sectors of the community.
E/ECA/PADIS/SCH/SC5.1E Systems able to provide the above level of services are now being called Network Information Centres or NICs. The Network Applications and Information Centre (NAle)at NASA's Ames Research Centre (Moffet' Field, California) has published the Network Information Centre Guidelines which provide a detailed outline of the scope ofactivities lAd performance criteria for a NIC.
Currently most African countries are not able to support the full range of activities expected ofaNIC. One ofthemajor problems in obtaining full Internet links is the very low bandwidth and high cost of available leased lines. In most African countries 9.6K baud is the maximum sizeavailable for any national or international data line. This is barely enough for a half-dozen simultaneous interactive sessions and can hardly be expected to serve a large population of users. Duplicate lines could be installed, but this requires substantially greater setup and maintenance costs and does not provide the efficiency and volume discounts associated with higher bandwidth connections. As it is, many 9.6K international leased line links are only marginally cheaper to operate than regular daily scheduled IDD calls.
Although this is likely to change in the future asPTTs improve their infrastructure, hosts setting up permanent Internet links will also need to establish effective local mirrors of popular internationaldata sources to help reduce traffic on scarce bandwidth. During the day the link is likely to be reserved for electronic mail and any other more urgent information requirements, while slack times at night could be used for updating mirrors and the local online newsgroups.
3.1.2 System Requirements
The minimum requirements for operating the most basic local host are a system operator, adedicated phone line, modem and a PC (even an XTclass IBM compatible can be used).
Some systems operate onashared fax line or on a business phone line after hours, but thiscan only provide a very limited service since users cannot necessarily dial in at any time that is convenient to them.
From the baseline of a single phone line and low-end PC, which can handle only a few dozen users on a store and forward email. service, the system can be expanded almost indefinitely upwards. A faster PC can reduce processing time between calls so that over 150 users can be supported on a single phone line if they are using offline reader software to minimisethe time spent on the phone (see below). A single 486 PC running DOS multitasking software can support further phone lines. Usually up to 4 simultaneous sessions can be supported, provided the equipment has sufficient RAM.
To supporta permanent connection to the Internet, a router and TCP/IP networking cards and software must be added to the system. For Internet hosts providing the full range of Internet serviceslocally, it isusually necessary to operate a UNIX host. This can be a version of UNIX for the 386/486. For larger systems, such as national hubs and hosts which have hundreds of users, a more powerful UNIX system based on Pentium, Rise or Spare chip architecture is needed. To store the complete operating system, networking software and sources, as well as a reasonably comprehensive set of international newsgroups and some databases, at least 2 Gigabytes of hard disk space is desirable. This caneasily be expanded up to 75 Gigahytes depending on the archiving requirements of the site.
System specification minimum requirements summary:
Feature 1 User 1 line 4 line 16 line 64line
CPU 8086 286 386 486 68040/Sparc/RiscIArm
RAM 256K 5I2K 8MB 32MB 64MB
DISK 720K 80MB 500MB 2GB 2GB
For a localhost to establish a full Internet connection, agreement with the appropriate remote Internet service provider is necessary, so that the requirements of the leased line can
..
beestablished and
thenobtainedfrom the telephone service provider, usually thePTf. Jf the PIT does notprovide a modem for the end of the leased line, a good quality synchronous modem willbe needed. This will be connected to the router, which can be a 286 MS-DOS machine for small hosts, but is moreusually apurpose built dedicated router, the capacity ofE/ECA/PADIS/SCH/SC5.1E
.wWdtwill varydepending on the number and bandwidth of the leased line connection tobe
provided. 1be router is in tum connectedto the host via standard TCP/IP ethernet card connections.
Forimproving reliability, reducing maintenance costs and increasing information access, thefollowingcanbeadded:
- Streamingtape drive - QIC format for small systems, DAT format on large hosts.
- CD-ROM drive - Single drive, up to dozens for multiple database access.
- link - AT-BUS interface card, UNIX X.25 software or dedicated PAD.
- Power regulation& UPS - 15 minutes battery up to 24hour diesel generator.
- High speed modems - 14.4K V.32bis, up to 28.8K V.34 - Backup hardware - duplicatesofcurrent system components.
- Terminalserver - selVesadditional modems/phone lines.
Despiteallthe hardware listed above, the capital costs of establishing a host are relatively small compared tothe administrative overheads, communications costs (especially for leased line or international connections) and staff costs. The latter in particular, can be high if skilled UNIX system operators are required. Ingeneral, a local host withafew hundred userswill require a full time technical/system support person, a full time user support person, and half
time direction and financial administration.
i
Withthegrowing importance of these communications services, their reduced cost and the increased standardisation of software with built-in support for WAN functions, a growing number of larger organisations are installingtheirown smaller versions ofthese localpost officestodealwith the demands for these facilitiesby their staff and constituencies.
These are
described in section3.2.3 below on LAN-to-WAN" links.
3.2 Network Infrastructure
Whether a user has access to the full range of computer based networking toolsisto a large extent determinedby the networkinfrastructure that is available, as described below.
3.2.1 voice Telephone Lines
Connecting computers over standard voice grade telephone lines relies on the use of modernstoprovide the interface between the digital signals of thecomputer and the analogue signals used for voice grade phone lines. In most cases the modem being used for communications is connectedtoanexisting telephone linealreadybeing used for voice or fax communications. It is unnecessary todedicate a lineto the task unless the volumeof traffic issuch that it wouldbeunavailablefor other purposes for long periods of time. When the line isin useby themodem, it becomes engaged in the sameway asit would for a normal voice or fax call.
Therecan bedifficulties where thephone line available is connected to an office PABX system wherea press-button system is used toobtain anoutside line. Since amodem doesnot havethisability to select an outside line, its wiring must bypass the PABX switch. This, however, can still leave the line susceptible to interruption from otherPABX users whomay beunaware of themodem communications taking place and attempt to accessthe line atthe
same time for normal voice calls.
Initially, very low transfer rates of only 30 or 120 characters per second (300 or 1200 bits per second (baud)) were the maximum achievable. However, modem technology hassteadily
improved to the point where a transfer rate of 28800 characters per second (28.8K baud) is availablewithtop-end modems. If files are not pre-compressed before transmission, in-transfer
modem compression (MNP5 or V42 protocols) can yield up to 115K baud transmission
speeds.
E/ECA/PADIS/SCH/SC5.1E 3.2.2 Packet switchin~ Services
Publicaccesspacketswitching services havebeeninstalledbymanyP'ITs as theirresponse to users' demands for a data service. They allow the use of a local phone call to connect computers to the PTT's packet switched network via an X.28 PAD. A permanent X.25 connection can also be leased from the P1T for providing continuous access to thelocal computerviathe X.25 network. Once connected to the local PAD, commands canbe issued to link the user's PC toanyother system (locally, nationally or internationally) connected to the worldwideX.25 network(lPSS).
There are now 15 African countries where this service is available: Botswana, Cote D'Ivoire, Djibouti, Egypt, Gabon, Gambia, Kenya, Mauritius, Mozambique, Namibia, Niger, Senegal, South Africa, Tunisia and Zimbabwe. (Tanzania is to have a service shortly).
ThePTf -national post office or telephone company is almost always the operator of such a service and usually installs public dialup connection points in the major cities. Most large local public-access and commercial hosts in Europe and North America provide access for their users via this type of service, but there are almost no local hosts in Africa with this facility. As a result African X.25 networks are mainly used to connect to systems outside the continent.
As long as the connection to the local X.25 PAD is reasonably good and is only a local phone call away~ a reliable connection to the host computer can be achieved and it is relatively simple to access a wide range of networks with this method.
To gain access to these services, a NUl (Network User ID) must be rented from the local P'IT. This comprises a registration or setup fee, monthly or quarterly rental, and usage charges to connect to the remote host. The host providing the connection at the remote end bills separately for the use ofitsservices.
SiDce X.25 networks charge mainly for the quantity of data that passesthrough the 8dwOrk, the usage chargesgenerally comprisea large part of the cost. For sendingand mceiving messages, upto 90% of the cost canbe in the charges madeby the localPI'T for thedatatraffic of theNUl.
Forregularusers making useofinteractive services such as databasesearches, NUl rental can provide a significantly cheaper option than making a direct dial long distance or international phone call tothe electronic host. If however, the host is accessed infrequently, then the cost of a NUl may not be justified.
Rate structures for PSS are complex and the monthly costs of using such a service to
connecttoa host can vary enormously from one country to another. Rental charges for a NUl canvary from $20 to $200 a Quarter. Some PTf's expectthe NUl user to rent PTI'owned modemsat highrates. Even usage charges (which are based ontime spent online, the location of the remote connection and the volume ofdata passed down the network) can varybya factor of 5 between different PTTs.
As a result using IPSS in some countries can be too expensive as a base for e-mail communications. Whereveritis available in Africa, itisusually considerably more expensive thanin theindustrialised countries. Medium tolow users ofinternational electronic mail hosts often have bills of between $250 and $1000 a month. On top of this certainPITsmayhave an IPSS thatconnects only tocertain countriesand not others.
For use on a national basis however, the X.25 networkcouldbe an effective means oflow cost communication.
..
Datachargesfor national traffic are usually very low and the provision of alocalaccess pointcan make this route to a central host verycost effective, especially for interactiveaccess. Wherenational trunkcircuits for voice gradephonelines are very noisy oroften busy, X.25 connections can provide more reliableaccess and errorfreeconnectionsif
die10callineis of good quality.
E/ECA/PADIS/SCH/SCS.1E
In most cases, even when used inside national borders, store and forward automatedmail protocols such as TCP/IP, UUCP and FillO are usually not cost effective over X.25. Because these protocols use the fuIl bandwidth of the link for almost continuous file transfer, the data traffic charges usually work out higher than the per minute charges of direct dialing withany modem faster than 1200 baud. In addition, protocols such as TCPJIP when run over X.2S
..
networks do not fill X.25 data packets efficiently and so are particularly inefficient and expensive tooperate. Nevertheless these protocols are in use where reliability and immediacy are of particular concern and cost is less important.
For dialup X.28 access most users do not have to concern themselves with the specifications of the X.25 connection. However, some networks support only even parity, so if 8 bit based applications are required over the network, users should establish if 8 bit connections are available.
Hosts wishing to support X.25 connections will need to install equipment with CCITI 1980, 1984 and 1988 compliance. This can be a standalone PAD which connects to the host via a series of serial ports for each simultaneous connection. Alternatively, and more commonly, software is run on the host which drives either a special serial port or an additional card on IBM PC compatible equipment. SunNet X.25 (Sun equipment), MorningStar Technologies and Adax are popular suppliers. Important features that X.25 software/hardware should include are: UUCP & 8 bit support, support for up to 4K packets, setting of remote PAD (X.3 parameters), and a trace facility.
3.2.3 Dedicated Networks
When there is more than one computer in an office, they are usually linked at the bare minimum with a printer switch enabling the sharing of a single printer. With low cost networking hardware and software now available, it is increasingly common to fmd
installationsofmore sophisticated networks allowing accessby any PCon thenetwork to the resources oftheother machines on the network andto remote machines ifa wide areanetwork link is installed.
A $100worth of equipment (network card plus cabling) and networking software on each workstation can allow applications stored on one machine to be run by a user on another computer, and can provide access to shared databases and mass storage media, immediate document transfer, meeting schedulingthrougha common calendar and other group activity functions.
As the volume of wide'area information networkingbeyond the LAN expands, a demand based temporarydialuplink over voice phone lines to a remote network can be replaced by a dedicated leased line connection using the same LAN networking protocols. A dedicated link has the added advantage ofallowing members of other remote networks tohave direct access to the information held on the local LAN.
Althoughthereare various low cost serial and parallel port LAN solutions, tiese have low throughput (less than 2Megabits per second) and cannoteasily be expanded be) ond twopes.
All full LANsystems require theinstallation of a dedicated networking card and appropriate cabling connecting the computerswhich should provide about 10Megabitsper second transfer
raes.
Although there are still a few office LAN systems not using ethernet based equipment, this isincreasingly rare. Ethernet has become the standard for almost all purpo~es except very large or high bandwidth (100 Megabitsper second), fibre optic networks usin~ FDDI (token ring) orATM networking technologies.Running over the Ethernet hardware, the two most dominant protocols are the commercial MS-DOS Novell IPX, and thepublicdomainTCP/IP.TCP/IP based LAN solutions have been gaininggroundwith their potential to be fully upgradable to OSI standards and the simplicity and seamlessnesswithwhich LANs canbeconnectedtotheTCP/IPbasedInternet WAN. The advantages of this solution have recently-become apparent to the major operatingsystems
E/ECA/PADIS/SCH/SC5.1E vendors - IBM, Microsoft and Apple - who have all put native TCP/IP support into their operating systems - OS/2, NT&Chicago/Windows95 and System 7.5 respectively.
LAN Cabling
In the past, a single thin co-axial cable (10Base2 or RG-58) has been popular for linking machines on an officeLANproviding a range of up to 185 metres per section of cable (upon which upto 30 machines can be connected in a BUS topology). For larger networks, thick Ethernet cable (10Base5 or RG-ll) can provide a backbone, with its range of up to 500 metres per segment. Larger networks can be constructed from up to five 10Base5 cables, two of which cannot have nodes attached to them (these two segments are used to increase the length of the network). Each of the three usable segments can haveupto j00 nodes attached to them, which works out at a maximum of 300 nodes per network.
The more flexible andreliable IOI3ase-T (RJ45) star topologysysten.s using twisted pairs of wires are now however cheap enough to warrant the marginal extra cost. These allow workstations to be up to ]00 metres from the hub, but up to 9 hubs (each supporting up to 1024 users) can be daisy chained if necessary. Because of their star topology, the reliability of the network as a whole is considerably increased because a cable breakage or modification at one workstation will not bring the whole network down. In the BUS topology, anycable breakage or modification affects all users.
The cost of cabling, installation and trouble shooting is less with IOBase-T systems for an office LAN larger than about 8 machines, but the disadvantage is that the cabling is less - tolerant of electrical interference and so cable length is more limited. This can be a problem in very large or widely dispersed offices. Shielded twisted pair \viring is less vulnrrablc t<.\
interference, bursignificantly more expensive.
Optical fibre will be the medium of choice for the future, being completely immune to electrical noise, but is the mostexpensive. However, optical fibre technologyis stillevolving rapidly and the cost issteadily dropping. Often in very noisy situations or high bandwidth
-OOSit is still worth the cost, especially because of its immunity from lightning - a major problem inAfrica.
Bridges
with
fibreoptic based links can be used to link moredistantly situated computers and LANs in largeorganisations, and where pes in separate buildings mustbe connected.Fibre optic backbones in large LAN and WAN installations are becoming increasingly commonas thecost of fibre technology fans and supportfor it becomes more widespread.
University campus networksin a growing number of African countries are basedon fibre rings, and even smaller networks are finding the highbandwidth and imperviousness to radio interference and lightning worth theadditional expense. These situations will undoubtedly call for an experienced network designer to configure the most appropriate system for these more complex situations.
LAN Software
Novell continues to dominate LAN network software installations with its Netware product, but Microsoft's products are gaining ground. Windows forWorkgroups is becoming anincreasinglypopularalternative for small peer to peer networks. Microsoft'sWindowsNT is being positioned as a direct competitor to Novell products for server based networks butit hasnot yetgained a significant degree of support among LAN solution suppliers. Windows for Workgroups, however, is becoming especially popular for small networks where a dedicated LAN server is not required. It is cheap and can be set upby any reasonably literate computer user.
If the technical expertise and support is available, networks offering the same or even greater functionality canbebuilt completely out of free public domainTCP/IP software. Most
'E/ECA/PADIS/SCH/SCS .1E
academicand researchdepartmentsat Universities make use of these solutions. Othersystems thatareabopopular include I..antastic, and Apple's AppletalkforMacintoshbased networks.
Appletalk networks inparticular can very easilybeupgraded to handleTCP/IP traffic with freely available software.
Most recent versions of LAN packages handle the TCP/IPtrafficthatis necessary for full connectivityto theInternetbyencapsulating the TCP/IP protocol inside their own proprietary networldng system. This does result insome loss ofefficiency through the increased overhead.
However, full implementations oftheTCP/IP protocol inthe LAN software have alreadybeen released or are expectedshortlyfrom mostvendors and this willoffer increased speed, more open connectivityand a simpler upgrade path to full Internet facilities. Furthermore, it will substantially simplify networked systems by making it possible to standardise on only one protocolforall LAN and WAN communications.
LAN to WAN links
Full Internetconnectivity for all users on a TCP/IP compatible LAN can be achieved simplybyadding arouter tothenetwork andconnecting it via a leased 2or 4 wire local lead line to the Intemet serviceprovideron the otherend.
A UNIX machine withappropriate software can be configured to act as a router as well, but because of the load this places on the machine, and the greater dependency it placeson a single pieceofequipment, itis usualto offload the routing function onto a dedicatedmachine.
CISCO Systems havedominated the market for dedicated routersbut others such as WellFleet and MorningStar are also popular. A low cost solution thatworksespecially well on low
•
speed (19.2 or 9.6K) lines is to usea PC as a router. KA9Q or PC-Route routing software can be used even on an 8086(XTclass) machine equipped with anethemetcard for the LAN connection andserialport for the leased line WAN connection. For higher than9.6K links, a 16550 buffered serial chip is advisable. For speeds greater than 19.2K it is possible toinstalilowcosta;ync-to-sync convertercards which allow the line to bedrivenat up to 64K. KA9Q is somewhat harder to configureand there are a number ofversions in circulation, but it is much more flexible than PC-Route and also allows the machine to multitask as an FTP and telnet terminal (PC-ROlltedoesnot allowanyother applicationsto be run).
Ifa2-wire line isused, a good quality Hayes compatible modemwith leased line mode and V.32 or V.32bis protocols, is quite sufficient as long as the modem at the other end supports the sameprotocol. Ifa4 wire lineis available (providing slightlyhigher throughput) a 4-wire baseband modem supporting a protocol such as V.29must beused at each end. A growing numberof mid-rangeHayes compatible modemssupportleased line as well as dialup modes, and somealso support 4-wire connections. Depending on the router configuration the modem may also be required to operate in synchronous mode, rather than the normal asynchronousmode. Again, manyofthe higherqualityHayescompatible modems now also support synchronousmode.
Atypeof leased line linkusingtheFrameRelayprotocol has become popular in developed countries and some more advanced ¥ITs in Africa have begun to provide this service to subscribers. Frame relay circuits usually run at 64K per second but the channel can be sub- divided into a number of Permanent Virtual Circuits(PVCs) to different locations. Frame relay hardware is necessary, the most common being a card with 4 channels which are accessed by the packet driverson the router. The router can bean ffiM compatiblePC running KA9Qor NovellIs multi-protocol routersoftware which supportsframe relay.
Automated demand baseddialupconnections tothe Internet over voice gradeJines are also in use. These have usually required the addition ofa UNIX system to the LAN, but a number of new dedicated dialup router products such as Telebit's NetBlazer and Rockwell's Netllopper, are now available, running on demand PPP or SLIP to the nearest full Internet site. These units are relatively simpleto set upand maintain - theyhave an Ethernet port which plugsintothe LANand aphone jackfor the telephone line. Users on theLANcan all
E/ECA/PADIS/SCH/SC5.1E
make use of the Internet connection at the same time, butthe limited bandwidth must be shared among the online users.
In most Africansituations a9.6Kanalogue line is themaximum speed ofleased linesthat are available. In manycases 4.8K is the maximum speed guaranteedby theYIT. However ithas been found that V.32b (19.2K) and V.Fe (28.8K) modems canbeused on these lines to improve throughputconsiderably, in some cases up to the maximum 28.8K possible. In other cases, while the localleads may beable to handle 28Ktransfers, the MUX on the local exchange may allocate a more limitedamount of bandwidth, effectively negating the advantages of a higher speed modem. Also voice grade lines may have specialised voice compression softwarerunning onthem to maximise voice channel capacity and this can also cause reduceddata traffic speeds, especiallywhere full-duplex protocols are in use.
The maximum number of users able to share a line also varies considerably depending on the type of applications being used across the line. Many hundred or even a few thousand userscan makeuseofsuchalink for email, which does not requireinteractive responses from the user, but graphicsintensiveoperations andmenu based systems which require fast response times can become frustratingly slow when more than 5-20 channels are in use, each subdividing the available bandwidth. High bandwidth data services using fibre optics and protocols such as ATM will become available in a fewindustrialised cities in Africain the short term as the PITs steadily upgrade their networks. Withthe major telecommunication infrastructure developments takingplace it is likely thatthese facilities will be extended to othercentresin the medium term.
Rural areas are unlikely to haveaccess to these services inthe foreseeablefutureand if high bandwidth connections are required, a satellite based VSAT (Very Small Aperture Terminal) system may be theonly solution. The relatively high cost of this technology is beyond the ambit of most small organisations and in many cases regulations and satellite transponderavailability may restrictaccess. Howeverlarger co-operating organisations and
groups may be able to considerthis option if a satellite withan appropriate downlink and bridgeto the required data services is available and ¥IT regulationsallow it.
3.2t,4 Alternative Transmission Media
Magnetic Media
In certainsituations othertechniquesfor moving data than those described above may be more appropriate. On the simplest level, hard media such as diskettes and tapes can beused to transmit data from one computer to another. Ifthe data is not particularly time sensitive, mailing of diskettes and cartridges can take the place of expensive international calls to download data -a 20 gram DATtapecan now hold 5 gigabytes or more of information.
Evenifan international Internet link isavailable, it maybe alow bandwidth 9.6K link in which case using a couriercompany to delivera big data set on tape (> IGigabyte) can be quicker and cheaperthan using the leased line. This situation can beseen in Zambiawhere the 9.6Kbs leased line costs about US$65 000 peryear.Even assuming continual use at maximum bandwidth, this corresponds to about US$150 per gigabyte, and since a gigabyte takes more than 24hours to download at 9.6Kbs it would bequicker and cheaper to ship the data via expressdeliveryon tape. Airmail of a 1.44MB diskette containing 4MB of compressed data can also save considerable expense for less time sensitiveinformation.
Lazer
Lazersystems are restricted to line of site operations butcan besuitedto local situations where" very high bandwidth links are required and cost is not critical (this uncommon
technologyis expensive). Theonlyknown installation in sub-Saharan Africa is between two units oftheGovernmentComputer Bureauin Maseru, Lesotho.
s havebeenemployed wheretraditional telephone
E/ECA/PADIS/SCH/SCS.1E Radio
cable based systems are not available. HF and UHF packet radio is the most popular, being used for terrestrial based networks and satellite based systems. The InternationalFederation of the Red Cross uses HF radio transmitters at some ofits field locationsin Africa to relay data via its head officein Geneva. Groundbased networksof packet repeater stationshave been erectedin many areas of the US buta networkof this sort has not been triedin Africa outsideofGovernment intelligenceandmilitary operations.
Nevertheless, terrestrial radio islikely to beincreasinglyused for linking areas outside the immediate locale of the cable based telephone network. Standalone solutions available to individual organisations are becoming cheaper - about US$2000 for the HF or UHF transceiver and TNC to connect it to the computer. Also, many African PTTs are installing small radiobasedrural subscriber exchanges such as Alcatel's RURTEL. Theseare effectively larger versions of the same technology with a number of standard subscriber telephones attached toit.
Radio connections to low earth orbiting satellites (LEOs) have been in use for a number
of yearsin manyAfrican countries byorganisations such as VITA and Satellife. The low orbit of the micro-satellites (which are essentially solar powered pes with a transceiver) makes it possibletouse a small transmitterand lightweighttracking aerial to connect with the satellite whenoverhead. Messages arestored on the satellite for download when the satellite is over the recipient's location, or where thereisa gateway on the groundstation to the Internet. The storage capacity and bandwidth of these systems is not high (9.6K for a maximum of 20-40 minutes adaywhen the satellite is in view) but the increased cost of the radio equipment can be justified where there is no telephonic link to the Wide Area Network.
There are a number of initiatives by commercial telecommunications groups, such as Motorola's Iridium project, to launch 'swarms' of LEOs to relay signals from anywhere 00
theplanetviasmallhandheld cellular telephones. These services are likelyto bevaluablein
isolatedareas, butthecostit basnot yetbeenestablished and it will be some years before they becomeapracticality.
Standardterrestrial cellphone networks are being set up ina growing numberof African countries and they can be used for data traffic if the appropriate equipment isused by the subscriber and the service provider. Cell phone connections use sophisticated compression techniques to maximise the voice capacity of the network and this is not conducive to data tlaffic.Cellphoneproviders can enabledatatraffic on a per userbasisand thisserviceusually adds tothecost. Cell phone handsets must be speciallymade to incorporate a data portand these are also more expensive than normal cellphones. Finally, the cellphone cannot be
simply plugged into a modem, but mustbe connectedto a specialiseddata interface card.
Sincecellular communication is mostlikelytobecarried outwithportable computers, these interfaces are usually onlyavailableas PCMCIA cards currently costingover US$l000.
Recent developmentsin theuse of geostationary satellites for the broadcast(i.e. download only) of high volumes ofdata, such as onlinemailing listsand files, to many sites at onceis nowinpractice. It has provided lowcost access ($30 a monthfor a full feedplus the cost of the dish)to muchoftheInternet services for those in the Americas and Asia. But the African market has not developed sufficientlyfor this to be worth the cost of settingup the uplink facility and leasing of the satellite transponder. Some possibilityalso existsto use the spare blanking lines in existing satellite television broadcasts tocarrydata. Such systems still rely on the telephone network for uploading information to the Internet, but generally far more informationisscannedand downloadedthan uploaded, so thisarrangement can stillbehighly cost effective when a service provider emerges.
Bi-directional satellite linn using VSATs as described above have been employed, especiallybyreliefagencies and television crews, but at relatively highcost. Inmarsathas generally been theonlyservicep~ovider inthis area withits Inmarsat C terminals which are available" for thispurpose andcost 4, to.5 USS a minute to use. Russian satellitesare now also
27
E/ECA/PADIS/SCH/SCS.1B available but many are aging andhave developed wobble,requiring sophisticated traekina equipment to operate. Recently PanamSat is launching a satellite which has abandwidth covering southern Africa and a numberof services are planned arounditscapacity,withusers requiring only a small simple 30 centimetre groundstation dish.
Terrestrial line-of-site connections (upto 50 kilometres) can nowbemade at upto 64KBPS transferrateswith UHF radio based equipment. Thissystem caneasilytake the place ofshort haul leased lines, often providing higher bandwidth, lower operating costs and increased reliability over conventional circuits. If greater distances are required it is possible to install repeater stations.
As with most radio technology, the difficulties of obtaining Government or PTT controlled authorisation canoften begreater than anytechnological barriers. The ease with which licenses are obtained varies considerably between countries and also depends on the nature of the application.
Ingeneral data transmission options which circumvent PlT services can be problematic and it is often more advantageous to attempt to involve the PIT through partnerships and assistance with fundraising for the installation of new services.
3.3 Operating Systems
With the growth inimportance of networks, operating systems are now being designedto
provide native support for networking capabilities. UNIX systems have long been the classic example of a network based operating system) which is one of the major reasonswhyUNIX machines have been so popular as local hosts. Apple has made its operatingsystem very easy to network and other operating systems are beginning to catch up. Novell has taken on development of both DOS and UNIX, and they will presumably have Novell network capabilities incorporated into them. While not technically an operating system, Microsoft's
networkproduct - Windows for Workgroups - hasvery littledependency on DOSandthe next versionwill notrequire prior installation of any operating system.
To date, Apple, Novelland Microsoft haveall used theirown proprietary networking standards, but new versions currently beingreleased froin all the major vendors, including IBM(with 0SI2IWarp), have built-in TCP/IP capability. This willbea major advance toward open systems connectivity and is likely to simplify substantially the job of linking diverse systems.
BothNovellandffiM areattemptingtocompete with Microsoft for the next generation of operatingsystems, but Microsoft's huge installedbaseof existing Windows users meansthat Chicago,or Windows95 as the new version is now called, is likelyto remain the market leader for workstation software. For dedicated file and network servers, Windows NT and IBM's new C)S2 Warp offer attractive options with their built in dialup TCP/IP facility which will allowthem to act as local hosts.
Apple is also pursuing the marketbut is likely to remain strong only in the publishing field whereithas developed a very strong following. In desk top publishing, the original design of theMacoperating system and longhistoryof software development in this environment has resulted in Apple products being the most common. With multimedia applications also particularly suited to the built in full sound and motion graphics capabilities of the Macs, Apple products are also particularly common in new multimedia sound and video editing suites
andpublishinghouses.
U:NIX is likely to remain popularin research, academic, applications development and dedicated networking environments, especiallywith the maturity of the public domain versions oftheoperating system - Linux and BSD386. Availablewith all source code, a large user supportbaseand a complete set of networking 'tools,theyarecurrently theoperatingsystem ofchoice for small low-cost local hosts.
E/ECA/PADIS/SCH/SC541E
4. APPLICATION SOFTWARE
Application software can conveniently be divided into programmes that are used for wide area networking functions and those that are used on local area networks. This division is steadily eroding aslocal area networks are more tightlylinked to wide
area
networks, butsoftwarethat is designed tooperatetransparently over both networks is still not generally used in Africaexceptperhaps for some electronicmail applications as described further below.
The explanation of the symbols following the names of recommended programmesis as follows:
(S) - Shareware - usually US$10-US$100 to registerafter ashort evaluation period.
($) - Commercial Package, could cost hundreds of dollars.
(SC) - Source codeavailable
Packages without a symbol after the name are free packages which anyone can usebut may or may not be copyrighted by the author. They may have restrictions on commercial redistribution. The latest versions of the shareware and free software can be found on most publicfile store sites on the Internet and FidoNet. In Africa, good sites include FfP.und.ac.za ftp.sun.ac.za, ftp.wn.apc.org and 5:7103/1. The files onwn.apc.org can alsobereceivedby email by sending a message to ftpmail@wn.apc.org.
4.1 Wide Area Networking Applications
Until recently, the conventional method of accessing all remote networking functions has beento use a terminal emulation programme such as Kermit or Procomm to dial up a remote host over a modem/phone connection and then use software resident on the remote host to transfer messages and files and access other services which may be available. This system requires the user tobe online for long periods of time if any significant amount of networking activity is to take place. With high cost and poor quality telephone lines this method of
connection canbeexpensive, unreliable and stressful for the operator. As a result software is . rapidlyswitchingtoprotocolbasedclient/server systemswhich use the intelligenceofthe local hardware as much aspossible~ automate network functions, transparently integrate with locallyrun applicationsand maximise efficient use of the telephone lineso~other transmission resources.
4.1.1 Terminal Software
Dumb terminal software is used for electronic mail in some cases where the local email host is not able to offer a protocol based service, or if the hardware available for email has restrictedabilityto run the moresophisticatedoffline software. In anycase, terminal software is still likelytobe required inmost installations for connecting to remotehosts, for browsing archives of information anddatabase searches.
While protocol based systems have their own error checking to cope with line interference, interactiveterminal sessions canbeseverely disruptedby noisy phone lines unless the modems on each end have some form of error correction system. The Microcom developed de-facto MNP 4 standard is supportedbythe majority of modem manufacturers, withthe superior V.42 standard becoming almost ascommon. Microcom have recently released the MNP level 10 protocol with Adverse Channel Enhancements (ACE) to cater for particularly poor quality lines.
Error free transfer of files is a basic function of terminal software with most programmes providing a range of Kermit, Xmodem andZmodem transfer protocols. Since Zmodem is supponedby most hosts and is the most efficient protocol in general use, terminal software without this capability shouldbe avoided. Zmodem is particularly valuable with large file transfers over dialup lines since, if the connection is broken, the subsequent session will resume the file transfer at the point of connection loss.
E!ECA!PADIS!SCH/SCS.1E Thereare increasingly sophisticated terminal emulation systems being implemented(such as RIP which provides a complete 'point&click' graphicalenvironment) however ANSIand VT100terminalemulation arestillthe baseline operating modeswhichshouldbeexpectedof any terminal package thatis adopted.
Low cost shareware and free terminal software is available for DOS, Windows and the Macintosh. However commercial software can have some marginal advantages such as improved scripting language, sophisticated dialingdirectoriesand a greatervariety of file transfer protocols supported. The fax software which comes packaged with many brandsof modems (such as QuickLinkII) oftenhas a terminal facility built into itas well.
A more limited terminal programme for use over TeP/IP networks is the Telnet programme. This software does not provide any file transfer capabilities (these are provided separately with other TCP/IP tools), but does provide simple terminal emulation such as VT100 as well as IBM 3270 emulation on some implementations.Telnet is usuallyused to connect from one system on the Internet to another for the purpose of running remote character based applications such as database queries. It requires that the full TCP/IP transport layer underneath be established first beforeaconnection to a remotecomputer is attempted.
The simplicity of these programmes generallymeans thatsupport from the developer is unlikely to be required.
Recommended Options:
- DOS: Telix (S), Kermit(SC), Terminate (S), Procomm-Plus ($), NCSA Telnet - MS Windows: WinRamp (S), Windows Terminal (comes with Windows), COMIT, - Procomm Plus for Windows($), Trumpet Telnet, WNQVT (5)
- Apple Mac: Zterm, Microphone(S), NCSA Telnet UNIX: Kermit,ell, Xterrn, Telnet,
