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Most existing criteria [3], [5], [8] for sizing router buffers rely on explicit formulation of the relationship between buffer size and characteristics of Internet traffic. However, this is a non-trivial, if not impossible, task given that the number of flows, their individual RTTs, and congestion control methods, as well as flow responsiveness, are unknown. In this paper, we undertake a completely...
Innovative efforts to provide a clean-slate design of congestion control for future high-speed heterogeneous networks have recently led to the development of explicit congestion control. These methods (N. Dukkipati, et al., Jun. 2005), (S. Jain, et al., June 2007), (D. Katabi, et al., Aug. 2002), (Y. Zhang, et al., April 2006) rely on multi-byte router feedback and aim to contribute to the design...
Real-time Internet services are gaining in popularity due to rapid provisioning of broadband access technologies. Delivery of high quality of experience (QoE) is important for consumer acceptance of multimedia applications. IP packet level errors affect QoE and the resulting quality degradations have to be taken into account in network operation. We derive the second order statistics of the number...
We evaluate the performance of a large-scale live P2P video multicast session comprising more than 120, 000 peers on the Internet. Our analysis highlights P2P video multicast characteristics such as high bandwidth requirements, high peer churn, low peer persistence in the P2P multicast system, significant variance in the media stream quality delivered to peers, relatively large channel start times,...
Peer-to-peer networks are voluntary resource sharing systems among rational agents that are resource providers and consumers. While altruistic resource sharing is necessary for efficient operation, this can only be imposed by incentive mechanisms, otherwise peers tend to behave selfishly. Selfishness in general terms means only consuming resources in order to absorb maximal utility from them and not...
Despite the huge success of the Internet in providing basic communication services, the Internet architecture needs to be upgraded so as to provide end-to-end QoS services to its customers. Currently, a user or an enterprise that needs end-to-end bandwidth guarantees between two arbitrary points in the Internet for a short period of time has no way of expressing its needs. To allow these much needed...
There is growing evidence that a new generation of potentially high-revenue applications requiring quality of service (QoS) guarantee are emerging. Current methods of QoS provisioning have scalability concerns and cannot guarantee end-to-end delay. For a theoretical fluid model, we derive four distributed rate and delay controls accounting for their bandwidth and end-to-end delay requirements while...
We investigate the delay of the bandwidth request under the truncated binary exponential backoff (TBEB) mechanism in the IEEE 802.16e, considering error-free/error- prone wireless channels. We derive the distribution of delay of bandwidth request packets in the TBEB by an analytic method on the assumption of Bernoulli request arrival process and error-free channel conditions, and extend the analytic...
This paper investigates the issues in making a delay-based protocol adaptive to heterogeneous environments. We address how a delay-based protocol can compete with a loss- based protocol such as TCP. We investigate if potential noise and variability in delay measurements in environments such as cable and ADSL access networks impact the protocol behavior significantly. We investigate these issues in...
Wireless multi-hop access networks are an increasingly popular option to provide cost-efficient last-mile Internet access. However, despite extensive research, performance of even basic communication services, such as TCP, is still problematic. Measurements collected on a wireless testbed indicate that the poor performance of multi-hop access networks is caused by poor interactions between TCP congestion...
This paper proposes an effective architecture to achieve QoS in distributed WLANs when multiple traffic streams are present and flowing through every single station. The 802.11e standard specifies a multiple-state-machine (MSM) structure in the medium access control (MAC) to address this QoS concern. However, our research indicates that the MSM structure was suboptimal. It increases the collision...
In sensor networks, application layer QoS requirements are critical to meet while conserving energy. One of the leading factors for energy wastage is failed transmission attempts due to channel dynamics and interference. Existing techniques are unaware of the channel dynamics and lead to suboptimal channel access patterns. We propose a MAC layer solution called pushback, that appropriately delays...
Firewalls are widely deployed nowadays to enforce security policies of enterprise networks. While having played crucial roles in securing these networks, firewalls themselves are subject to performance limitations. An overloaded firewall can cause severe damage to the protected enterprise network, because any legitimate communication through it is either degraded or even completely severed. In this...
The composition of services has been a useful approach to integrating business applications within and across organizational boundaries. In this approach, individual services are federated into composite services which are able to execute a given task subject to a service level agreement (SLA). An SLA is a contract agreed between a customer and a service provider who define a set of several quality...
This paper describes an experimental study that closely examines the underlying topologies of multiple complex networks formed in BitTorrent swarms. Our results demonstrate that the networks exhibit fundamental differences during different stages of a swarm, suggesting that the initial stage is not predictive of the overall performance. We also find a power-law degree distribution in the network of...
We show an isomorphism between maximal matching for packet scheduling in crossbar switches and strictly non-blocking circuit switching in three-stage Clos networks. We use the analogy for a crossbar switch of size n times n to construct a simple multicast packet scheduler of complexity O(n log n) based on maximal matching. We show that, with this simple scheduler, a speedup of O(log n/log log n) is...
Unexpected increases in demand and most of all flash crowds are considered the bane of every Web application as they may cause intolerable delays or even service unavailability. Proper quality of service policies must guarantee rapid reactivity and responsiveness even in such critical situations. Previous solutions fail to meet common performance requirements when the system has to face sudden and...
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