Technical reports

Open service support for ATM

Jacobus Erasmus van der Merwe

November 1998, 164 pages

This technical report is based on a dissertation submitted September 1997 by the author for the degree of Doctor of Philosophy to the University of Cambridge, St John’s College.

Abstract

Asynchronous Transfer Mode (ATM) technology provides superior transfer capabilities in an environment in which multiple services are provided and carried by a single network. Fully exploiting this potential is hampered by the assumption by standards bodies that a single control architecture, which was derived from a mono-service network, will filfil the needs of all applications in such a multi service environment.

While this weakness has been widely recognised, previous efforts to address it have met with limited success. This can be largely attributed to the fact that such attempts have often been proposed to replace one monolithic system with another. Avoiding this “one-size-fits-all” approach, this dissertation presents an Open Service Support Architecture (OSSA), in which multiple control architectures can be operational simultaneously in the same physical network. In this manner different control architectures, which provide diverse functionality and were designed to different models, can be accommodated.

A key concept of the OSSA is the partitioning of switch resources by a software entity called a Divider. The subset of switch resources is callled a switchlet, and the Divider allows each switchlet to be controlled by a separate control architecture. The divider polices the invocations of a control architecture to contain it in its allocated switchlet. Switchlets are combined into virtual networks, and a software entity called the Network Builder automates this process. The Network Builder allows virtual networks of arbitrary topology to by dynamically created and modified, and each virtual network is therefore controlled by a separate instance of a control architecture. The dissertation presents a proof of concept implementation of the OSSA, and reports on the efficiency of various implementations of crucial components.

The dynamic creation of virtual networks in the OSSA means that the usage of resources in an ATM network now needs to be considered on three time scales: short time scales for cell switching, longer time scales for connection creation, and even longer time scales for virtual network creation. The use of measurement based estimates of effective bandwidth to effect resource management at the two longer time scales of interest is investigated and the results presented.

Finally, the flexibility offered by the OSSA enables the use of service specific control architectures (SSCAs). An SSCA is a control architecture which utilises service specific knowledge in its manipulation of network resources, thereby providing a more efficient service than would be possible with a general purpose control architecture. The design and implementation of an SCCA for continuous media conferencing is presented.

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BibTeX record

@TechReport{UCAM-CL-TR-450,
  author =	 {van der Merwe, Jacobus Erasmus},
  title = 	 {{Open service support for ATM}},
  year = 	 1998,
  month = 	 nov,
  url = 	 {https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-450.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  doi = 	 {10.48456/tr-450},
  number = 	 {UCAM-CL-TR-450}
}