A core stateless bandwidth broker architecture for scalable support of guaranteed services

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. 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.

我们提出一种新颖的带宽代理架构，用于可扩展地支持有保证的服务，该架构将QoS控制平面与分组转发平面解耦。更具体地说，在这种架构下，核心路由器不维护任何QoS预留状态，无论是基于流的还是聚合的。相反，QoS预留状态由带宽代理存储和管理。这种带宽代理架构有几个优点。其中，它避免了传统的逐跳分布式准入控制方法所面临的QoS状态不一致的问题。此外，它使我们能够设计高效的准入控制算法，而不会在核心路由器上产生任何开销。所提出的带宽代理架构是基于最近开发的核心无状态虚拟时间参考系统设计的。这个虚拟时间参考系统提供了一个统一的框架，以便根据支持延迟保证的能力来描述核心路由器的每跳行为及其连接的端到端特性。我们重点关注在所提出的带宽代理架构下高效准入控制算法的设计。我们考虑基于流的端到端有保证延迟服务以及具有流聚合的基于类别的有保证延迟服务。利用我们的带宽代理架构，我们展示了如何基于每个域而不是“逐跳”进行准入控制。这种方法可以显著降低准入控制算法的复杂性。在设计基于类别的准入控制算法时，我们研究了在提供有保证延迟服务中动态流聚合的问题，并设计了一种新的装置来有效规避这个问题。我们进行详细的分析，为我们的方案提供理论基础并确立其正确性。我们还进行了模拟以证明我们方案的有效性。