Department of Computer Science and Technology

Technical reports

Site interconnection and the exchange architecture

David Lawrence Tennenhouse

October 1989, 225 pages

This technical report is based on a dissertation submitted September 1988 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Darwin College.

DOI: 10.48456/tr-184


The users of a site’s telecommunication facilities rely on a colection of devices, transducers and computers, to provide the primary communications interface. In the traditional approach to site interconnection, some of these devices are directly attached to specialised carrier networks. The remaining devices are attached to local networks that are tailored to support communication amongst compatible devices at remote sites. This arrangement does not reap the full benefits of network and service integration: each local network has its own common carrier interfaces; and there is no provision for device independent processing, storage, and forwarding elements.

This dissertation describes a layered approach to site interconnection. Communication between peer sites is supported by the lower layer carrier networks, and associations between upper layer clients are supported by the local network layer. The site interconnection layer, inserted between the lacal and carrier layers, facilitates communication between peer local networks. This layer is composed of independent subsystems that offer the site interconnection service (SI-service) to their upper layer clients. Each SI-subsystem is a funnel through which various device-dependent symbol sets are encoded into a common digital format. The symbol streams of concurrent upper layer associations are multiplexed together for presentation at the shared carrier interfaces. Service integration is achieved through the encoding of many different styles of communication (vioce, video, facsimilie, tile transfer, etc.) into a common symbol set.

The first part of this dissertation develops the connected argument sharing this layered architecture. The second part describes the experimental development and analysis of the exchange architecture, which provides an SI-service that supports Asynchronous Transfer Mode (ATM) communication. The ATM approach is characterized by the use of small packets in conjunction with switch fabrics that provide comprable performance to circuit switching, and permit much greater variability in traffic patterns. The switch fabric of the pilot implementation is based on the Cambridge Fast Ring: the CFR packet structure is the basis of the ATM encoding; and the VLSI ring technology has been used to construct the individual SI-subsystems. In this application, the CFR provides ATM-based switching and multiplexing facilities.

This work is distinguished by its emphasis on site independence and universal access to telecommunication services. The principal contributions to the thesis relate to site interconnection; ATM encodings; out-of-band and non-invasive network management; particular analysis methodologies; and the design of multi-service networks.

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BibTeX record

  author =	 {Tennenhouse, David Lawrence},
  title = 	 {{Site interconnection and the exchange architecture}},
  year = 	 1989,
  month = 	 oct,
  url = 	 {},
  institution =  {University of Cambridge, Computer Laboratory},
  doi = 	 {10.48456/tr-184},
  number = 	 {UCAM-CL-TR-184}