Department of Computer Science and Technology

Technical reports

Dynamic bandwidth management

Bhaskar Ramanathan Harita

160 pages

This technical report is based on a dissertation submitted October 1990 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Wolfson College.

DOI: 10.48456/tr-217


Recent advances in semiconductor and optical technologies have contributed greatly to the evolution of broadband integration of multi-service traffic. The asynchronous transfer mode (ATM) has been proposed as the target technique for broadband integrated services digital networks (BISDNs) based on fast packet switching and optical fibre transmission. A primary advantage of ATM is that variable bit rate services can be supported efficiently, which meets the basic needs of flexibility and service independence required of integrated services networks. In order to fully exploit this flexibility and enchance network efficiency by statistical multiplexing it is important that there be effective methods of bandwidth management and congestion control.

This dissertation describes the use of dynamic bandwidth management to support an ATM overlay superimposed on a public, primary rate ISDN. The overlay architecture provides for the flexible aggregation of switched circuits into larger bandwidth channels. The channels are formatted into a common packet encoding and packets from different sources are statistically multiplexed onto them. In this work, different control schemes that dynamically vary the bandwidth of the channels in a transparent fashion, using out-of-band signalling, are contrasted. The bandwidth is adjusted by adding or deleting circuits in reaction to the traffic rates and the queue sizes at the channels. Performance models of simple bandwidth control schemes as queueing schemes are analysed by the use of moment generating functions

Packet transfer on the overlay is virtual circuit based and connection requests are accepted on the basis of their bandwidth requirements. Dynamic bandwidth management is used to supplement static bandwidth allocations in a congestion control framework presented for the overlay. The cost effectiveness of dynamic bandwidth control is examined for the tarrif structure implemented by the underlying public ISDN.

The contributions of this dissertation are the development of schemes for dynamic bandwidth management, their implementation on an ATM testbed and the analysis of performance models for bandwidth control validated by simulation and experiment.

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BibTeX record

  author =	 {Harita, Bhaskar Ramanathan},
  title = 	 {{Dynamic bandwidth management}},
  url = 	 {},
  institution =  {University of Cambridge, Computer Laboratory},
  doi = 	 {10.48456/tr-217},
  number = 	 {UCAM-CL-TR-217}