Networks and Switching for B-ISDN Connectionless Communications--Issues on Interworking of Two Connectionless Services, Network Topologies and Connectionless Message Switching Method--

Katsuyuki YAMAZAKI  Yasushi WAKAHARA  Yoshikazu IKEDA  

IEICE TRANSACTIONS on Communications   Vol.E76-B   No.3   pp.229-236
Publication Date: 1993/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Broadband ISDN --Application, Networking and Management--)
ATM,  B-ISDN,  connectionless communications,  

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Widespread penetration of data communications in a LAN environment is generating a demand for high speed data transfer over wide area networks. It is anticipated that the connectionless (CL) service based on IEEE802.6 technology, called Switched Multi-megabit Data Service (SMDS), will be employed before this is realized by B-ISDN based technology. An important early application of B-ISDN will be interconnections between LANs, and continued support of the IEEE802.6 based CL service. This paper first reviews relevant technologies, clarifies comparison between IEEE802.6 based and B-ISDN based CL services, and points out that the important feature for users is that both CL services conform to the E.164 ISDN numbering plan for message addressing. Since an addressing scheme is the key to network services, conformity between the two will easily rationalize service migration from the IEEE802.6 based CL service to the B-ISDN based CL service. To permit such a service migration, this paper considers interworking scenarios for two CL services taking account of the penetration of inter-LAN communications. An exploring path is also presented to that users will not need to be aware of an alternation of network configuration, and smooth migration can take place. For facilitating high volume CL communications in the B-ISDN era, a virtual CL network is discussed to utilize ATM functionalities and to realize broadcasting and robust connectionless service capabilities. An overall comparison between a ring and mesh/star topology for the CL network is presented, and a detailed performance study is addressed in the context of Quality of Service which may depend on the particular application. This paper then describes a connectionless switch architecture in which a message switch combined with an ATM cell channel switch is presented. One scheme which receives specific attention here is a non-assembly message switching method to achieve robust switching capabilities. Typical performance evaluation results based on an M/G/1 queueing model are also reported.