ISO transport arrives on top of the TCP (RFC0983)
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2001-Jul-13
Internet Society Requests For Comment (RFCs)
D.E. Cass: AUTHOR [+2]
Status of This Memo
Network Working Group D. E. Cass (NRTC) Request for Comments: 983 M. T. Rose (NRTC)
ISO Transport Services on Top of the TCP
Status of This Memo
This memo describes a proposed protocol standard for the ARPA Internet community. The intention is that hosts in the ARPA-Internet that choose to implement ISO TSAP services on top of the TCP be expected to adopt and implement this standard. Suggestions for improvement are encouraged. Distribution of this memo is unlimited.
1. Introduction and Philosophy
The ARPA Internet community has a well-developed, mature set of transport and internetwork protocols (TCP/IP), which are quite successful in offering network and transport services to end-users. The CCITT and the ISO have defined various session, presentation, and application recommendations which have been adopted by the international community and numerous vendors. To the largest extent possible, it is desirable to offer these higher level services directly in the ARPA Internet, without disrupting existing facilities. This permits users to develop expertise with ISO and CCITT applications which previously were not available in the ARPA Internet. It also permits a more graceful transition strategy from TCP/IP-based networks to ISO-based networks in the medium- and long-term.
There are two basic approaches which can be taken when "porting" an ISO or CCITT application to a TCP/IP environment. One approach is to port each individual application separately, developing local protocols on top of the TCP. Although this is useful in the short-term (since special-purpose interfaces to the TCP can be developed quickly), it lacks generality.
A second approach is based on the observation that both the ARPA Internet protocol suite and the ISO protocol suite are both layered systems (though the former uses layering from a more pragmatic perspective). A key aspect of the layering principle is that of layer-independence. Although this section is redundant for most readers, a slight bit of background material is necessary to introduce this concept.
Externally, a layer is defined by two definitions:
a service-offered definition, which describes the services provided by the layer and the interfaces it provides to access those services; and,
Cass Rose [Page 1]
RFC 983 April 1986 ISO Transport Services on Top of the TCP
a service-required definitions, which describes the services used by the layer and the interfaces it uses to access those services.
Collectively, all of the entities in the network which co-operate to provide the service are known as the service-provider. Individually, each of these entities is known as a service-peer.
Internally, a layer is defined by one definition:
a protocol definition, which describes the rules which each service-peer uses when communicating with other service-peers.
Putting all this together, the service-provider uses the protocol and services from the layer below to offer the its service to the layer above. Protocol verification, for instan...