1,144 research outputs found
Queue Dynamics With Window Flow Control
This paper develops a new model that describes the queueing process of a communication network when data sources use window flow control. The model takes into account the burstiness in sub-round-trip time (RTT) timescales and the instantaneous rate differences of a flow at different links. It is generic and independent of actual source flow control algorithms. Basic properties of the model and its relation to existing work are discussed. In particular, for a general network with multiple links, it is demonstrated that spatial interaction of oscillations allows queue instability to occur even when all flows have the same RTTs and maintain constant windows. The model is used to study the dynamics of delay-based congestion control algorithms. It is found that the ratios of RTTs are critical to the stability of such systems, and previously unknown modes of instability are identified. Packet-level simulations and testbed measurements are provided to verify the model and its predictions
Active Queue Management for Fair Resource Allocation in Wireless Networks
This paper investigates the interaction between end-to-end flow control and MAC-layer scheduling on wireless links. We consider a wireless network with multiple users receiving information from a common access point; each user suffers fading, and a scheduler allocates the channel based on channel quality,but subject to fairness and latency considerations. We show that the fairness property of the scheduler is compromised by the transport layer flow control of TCP New Reno. We provide a receiver-side control algorithm, CLAMP, that remedies this situation. CLAMP works at a receiver to control a TCP sender by setting the TCP receiver's advertised window limit, and this allows the scheduler to allocate bandwidth fairly between the users
FAST TCP: Motivation, Architecture, Algorithms, Performance
We describe FAST TCP, a new TCP congestion control algorithm for high-speed long-latency networks, from design to implementation. We highlight the approach taken by FAST TCP to address the four difficulties which the current TCP implementation has at large windows. We describe the architecture and summarize some of the algorithms implemented in our prototype. We characterize its equilibrium and stability properties. We evaluate it experimentally in terms of throughput, fairness, stability, and responsiveness
Managing network congestion with a Kohonen-based RED queue
The behaviour of the TCP AIMD algorithm is known to cause queue length
oscillations when congestion occurs at a router output link. Indeed, due to
these queueing variations, end-to-end applications experience large delay
jitter. Many studies have proposed efficient Active Queue Management (AQM)
mechanisms in order to reduce queue oscillations and stabilize the queue
length. These AQM are mostly improvements of the Random Early Detection (RED)
model. Unfortunately, these enhancements do not react in a similar manner for
various network conditions and are strongly sensitive to their initial setting
parameters. Although this paper proposes a solution to overcome the
difficulties of setting these parameters by using a Kohonen neural network
model, another goal of this study is to investigate whether cognitive
intelligence could be placed in the core network to solve such stability
problem. In our context, we use results from the neural network area to
demonstrate that our proposal, named Kohonen-RED (KRED), enables a stable queue
length without complex parameters setting and passive measurements.Comment: 8 pages, 9 figure
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