A Core Stateless Bandwidth Broker Architecture for Scalable Support of Guaranteed Services

Zhenhai Duan, Zhi Li Zhang, Yiwei Thomas Hou, Lixin Gao

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41 Scopus citations


We present a novel bandwidth broker architecture for scalable support of guaranteed services that decouples the QoS control plane from the packet forwarding plane. More specifically, under this architecture, core routers do not maintain any QoS reservation states, whether per-flow or aggregate. Instead, the QoS reservation states are stored at and managed by a bandwidth broker. There are several advantages of such a bandwidth broker architecture. Among others, it avoids the problem of inconsistent QoS states faced by the conventional hop-by-hop, distributed admission control approach. Furthermore, it allows us to design efficient admission control algorithms without incurring any overhead at core routers. The proposed bandwidth broker architecture is designed based on a core stateless virtual time reference system developed recently. This virtual time reference system provides a unifying framework to characterize, in terms of their abilities to support delay guarantees, both the per-hop behaviors of core routers and the end-to-end properties of their concatenation. In this paper, we focus on the design of efficient admission control algorithms under the proposed bandwidth broker architecture. We consider both per-flow end-to-end guaranteed delay services and class-based guaranteed delay services with flow aggregation. Using our bandwidth broker architecture, we demonstrate how admission control can be done on a per domain basis instead of on a "hop-by-hop" basis. Such an approach may significantly reduce the complexity of the admission control algorithms. In designing class-based admission control algorithms, we investigate the problem of dynamic flow aggregation in providing guaranteed delay services and devise a new apparatus to effectively circumvent this problem. We conduct detailed analyses to provide theoretical underpinning for our schemes as well as to establish their correctness. Simulations are also performed to demonstrate the efficacy of our schemes.

Original languageEnglish (US)
Pages (from-to)167-182
Number of pages16
JournalIEEE Transactions on Parallel and Distributed Systems
Issue number2
StatePublished - Feb 2004

Bibliographical note

Funding Information:
The authors would like to thank the anonymous reviewers of ACM SIGCOMM 2000 and IEEE Transactions on Parallel and Distributed Systems for many valuable comments. Z. Duan and Z.-L. Zhang were supported in part by US National Science Foundation (NSF) Grants CAREER Awards NCR-9734428, EIA-9818338, and ITR ANI-0085824. Lixin Gao was supported in part by NSF Grants ITR ANI-0085848 and ANI-0208116. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the US National Science Foundation. An abridged version of this paper appeared in Proceedings of the SIGCOMM 2000 with the title “Decoupling QoS Control from Core Routers: A Novel Bandwidth Broker Architecture for Scalable Support of Guaranteed Services.”


  • Admission control
  • Bandwidth broker
  • Flow aggregation
  • Network resource management
  • Quality of services


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