Recently, the Asynchronous Transfer Mode (ATM) has been advocated as an important technology for the wide area interconnection of heterogeneous network types, including traditional packet and synchronous switched networks. We consider that the advantages of ATM for the wide area also extend into the local area. The interconnection of these local and wide area networks to provide an end-to-end ATM service is an important component in providing a flexible service to applications.
Computer manufacturers are beginning to promote the use of ATM techniques in privately owned and operated digital networks. Many networking companies are coming forward offering private ATM solutions with a promise to migrate to upcoming standards (e.g. from CCITT) and emerging de facto standards (e.g. from the ATM Forum).
There has been a trend for certain workers in the field to associate the term `ATM' with the full set of CCITT recommendations for Broadband ISDN. We take our definition of ATM from the the broader meaning of the term actually defined by CCITT in recommendation I.113; that is:
the use of a fixed-length cell as the primary means of information transfer where the periodicity of cells is not known by the receiver in advance, but is indicated by a label in the cell header.For an ATM system to inter-work with other ATM systems there must be an agreed set of functions and associated semantics which each of the systems supports. Taking interoperation with B-ISDN as a pre-requisite, this requires primarily the support of a subset of the user plane semantics of the CCITT definition of the B-ISDN ATM layer. This gives:
Collaborative research work to investigate this approach is being carried out at the University of Cambridge Computer Laboratory and at Olivetti Research Ltd. We are developing ATM host interfaces for standard workstations and have implemented the MSNA protocol suite in UNIX and in an experimental kernel called Wanda [4]. In this paper we present an overview of MSNA and relevant adaptation issues together with the design and performance results of an ATM interface for the DEC Turbochannel.