VIRTUAL CIRCUITS VS. DATAGRAMS - POLITICAL
It should be apparent by now that there is something else than technical under the rug.
Indeed, manufacturers and users unanimously declare the view (as they say in CCITT) that there is a need for E-E protocols independent from transport facilities. This is an overwhelming position supported by scores of 19,20,21,22,23,24,27,28 papers . ISO has now started working on the standardi-zation of an E-E protocol (TC 97/SC6/Project 17), which would allow data transfer between data processing equipments, regardless of the transport facilities used. IFIP-WG6.1 has already proposed such a protocol after extensive discussion and experimentation within network groups at international level. Therefore, one might think that the carriers would make every effort to take this approach into account in designing interfaces with public transport facilities, e.g. make it easyto superimpose E-E protocols on packet transport, and avoid the duplication of functions.
Some computer manufacturers have already expressed their preference for a specific transport facility : the DG. Others have not, and this includes IBM. Their position is that they cannot take a stand as long as specifications, quality of service, tariffs, are not known. Fair enough, because adaptation costs and effectiveness cannot be assessed without these essential parameters. But a certain number of institutions have already expressed a definite support for a DG facility. This includes IFIP-WG6.127,28, the EIN community, the Industrial and Technological Directorate of the European Communities, the French Direction of Industry, and various users of large private networks.
Positions on CVC's are more polite. Everyone supports more or less CVC's without comment. It is not considered as a wise stand to antagonize the European PTT's when they are known to be ticklish (PTT's are telecommunications state monopolies). Manufacturers are even more cautious, since they always have some proposal hung up somewhere on a PTT desk. And after all, if CCITT standards are awkward, manufacturers will have a good excuse for selling their customers additional hardware. In case customers would then shy away from public packet networks, God bless the CCITT. Private networks are a bonanza.