A Scalable Framework for IP-Network Resource Provisioning Through

There has been an increasing need to make the Internet architecture capable of meeting the diverse service requirements of newly emerging applications such as multimedia conferencing and e-Commerce. This thesis addresses the following question: Is it possible to deliver latency-sensitive applications (LSAs), e.g., streaming audio and video, with satisfactory quality of service (QoS) in large-scale network without compromising scalability and bandwidth efficiency? Two previously proposed solutions are Integrated Services (Int-Serv) and Differentiated Service (Diff-Serv), but both have their own limitations that hinder their widespread deployments. Int-Serv requires per-flow signaling and state maintenance at every router (including edge and core routers) to provide per-flow performance guarantees. The main weakness of Int-Serv is its complexity that grows with the number of users. Differentiated Services (Diff-Serv), on the other hand, relies on packet marking at the edge router and class-based queuing at core routers to provide service differentiation. Although the Diff-Serv packet-level mechanisms are well-studied, many flow-level control problems and inter-domain resource allocation issues remain unresolved. In addition, existing work have mostly focused on network-level QoS (e.g., bandwidth guarantees, packet losses and delays) without considering how that relates to the application-level QoS, which matters the most to end users. We have proposed an innovative distributed control architecture, the Clearing House (CH), and a set of adaptive mechanisms to address these issues. Our design rationale is influenced by discussions with two major U. S. Internet service providers and driven by a realistic model of application-level performance requirements. Towards this end, we focus on Voice-over-IP (VoIP) as an example workload and perform subjective experiments to quantify the impact of packet losses and delays on perceived voice quality. Our results show that packet loss rate should be below 1% and per-hop delay should at most be 5 ms to guarantee high-quality VoIP delivery. Two key ideas that contribute to the scalability of our CH architecture are: aggregation and hierarchical control. Our approach exploits the inherent hierarchy of the Internet structure and peering relationships between ISPs. In our model, various basic routing domains are aggregated to form logical domains (LDs), which can then be aggregated to form larger LDs and so forth. This introduces a hierarchical tree of the LDs, and a CH-node is associated with each LD. This hierarchical tree of CH-nodes forms a "virtual overlay network" on top of existing wide-area network topology. The processing load and state maintenance required to manage an entire ISP domain are now distributed to various CH-nodes at different levels of granularity. The CH-nodes establish bandwidth reservations on intra- and inter-domain links for aggregate traffic (trunk), rather than individual flows, so that no per-flow management is required at any routers. We approximate the arrival process of trunks as Gaussian, and measure their corresponding mean and variance during a chosen measurement window. Aggregate reservations are set up based on the measured statistics and the QoS performance goal (e.g., tolerable loss rate). Using VoIP as an example workload, our simulations show that this technique can achieve a loss rate of 0.12% with only 8% over-provisioning. In addition to resource reservations, two other essential resource control tasks within CH are admission control and traffic policing. Admission control is necessary for limiting the usage of resources by competing flows, while policing is useful for detecting and penalizing malicious flows (i.e., flows that violate their allocated share of bandwidth). For scalability, per-flow admission control is only performed at ingress points of an ISP domain, but it should consider the network-wide congestion level in estimating the impact of a