Enhancing wireless TCP a serialized-timer approach

IEEE INFOCOM Proceedings, 2010, p. 1-5In wireless networks, TCP performs unsatisfactorily since packet reordering and random losses may be falsely interpreted as congestive losses. This causes TCP to trigger fast retransmission and fast recovery spuriously, leading to under-utilization of available network resources. In this paper, we propose a novel TCP variant, known as TCP for noncongestive loss (TCP-NCL), to adapt TCP to wireless networks by using more reliable signals of packet loss and network overload for activating packet retransmission and congestion response, separately. TCP-NCL can thus serve as a unified solution for effective congestion control, sequencing control, and loss recovery. Different from the existing unified solutions, the modifications involved in the proposed variant are limited to sender-side TCP only, thereby facilitating possible future wide deployment. The two signals employed are the expirations of two serialized timers. A smart TCP sender model has been developed for optimizing the timer expiration periods. Our simulation studies reveal that TCP-NCL is robust against packet reordering as well as random packet loss while maintaining responsiveness against situations with purely congestive loss. ©2010 IEEE.published_or_final_versio

On how to Mitigate the Packet Reordering Issue in the Explicit Load Balancing Scheme

科研費報告書収録論文(課題番号:17500030/研究代表者:加藤寧/インターネットと高親和性を有する次世代低軌道衛星ネットワークに関する基盤研究

Design and analysis of TCP AIMD in wireless networks

The class of additive-increase/multiplicative-decrease (AIMD) algorithms constitutes a key mechanism for congestion control in modern communication networks, like the current Internet. The algorithmic behaviour may, however, be distorted when wireless links are present. Specifically, spurious window reductions may be triggered due to packet reordering and non-congestive loss. In this paper, we develop a framework for AIMD in TCP to analyze the aforementioned problem. The framework enables a systematic analysis of the existing AIMD-based TCP variants and assists in the design of new TCP variants. It classifies the existing AIMD-based TCP variants into two main streams, known as compensators and differentiators, and develops a generic expression that covers the rate adaptation processes of both approaches. It further identifies a new approach in enhancing the performance of TCP, known as the compensation scheme. A tax-rebate approach is proposed as an approximation of the compensation scheme, and used to enhance the AIMD-based TCP variants to offer unified solutions for effective congestion control, sequencing control, and error control. In traditional wired networks, the new family of TCP variants with the proposed enhancements automatically preserves the same inter-flow fairness and TCP friendliness. We have conducted a series of simulations to examine their performance under various network scenarios. In most scenarios, significant performance gains are attained. © 2013 IEEE.published_or_final_versio

Accuracy and Dynamics of Hash-Based Load Balancing Algorithms for Multipath Internet Routing

This paper studies load balancing for multipath Internet routing. We focus on hash-based load balancing algorithms that work on the flow level to avoid packet reordering which is detrimental for the throughput of transport layer protocols like TCP. We propose a classification of hash-based load balancing algorithms, review existing ones and suggest new ones. Dynamic algorithms can actively react to load imbalances which causes route changes for some flows and thereby again packet reordering. Therefore, we investigate the load balancing accuracy and flow reassignment rate of load balancing algorithms. Our exhaustive simulation experiments show that these performance measures depend significantly on the traffic properties and on the algorithms themselves. As a consequence, our results should be taken into account for the application of load balancing in practice

SCTP robusto a retransmisiones espúreas

El objetivo de este artículo es contribuir en los aspectos relacionados con la degradación de performance en los protocolos de transporte confiables, ante el fenómeno de congestión de las redes globales, en particular tomando como modelo de referencia SCTP (Stream Control Transmission Protocol). Al problema de la congestión se suman el reordenamiento de paquetes y el cambio brusco del round-trip-time, muy común en redes wireless. Estos comportamientos de la red subyacente producen una seria degradación de la performance de los protocolos de transporte . Se propone para SCTP un mecanismo adaptativo con el fin de disminuir la ocurrencia de los denominados falsos timeouts y falsos fast retransmits, que producen degradación en performance y la subutilización de recursos, principalmente de ancho de banda y buffers. La extensión del protocolo SCTP que incluimos la denominamos “RR-SCTP”.The objective of this paper is to contribute to the analysis of degradation of performance in realible transport protocols in the presence of global networks congestion assuming, as the reference model, the case of the SCTP (Stream Control Transmission Protocol). Beyond the question of congestion, this study addresses packages reordering and round-trip-time abrupt changes that are very common in wireless networks. With the current congestion control mechanisms, these underlying network behaviors significantly degrade the performance of the transport protocols. We propose an adaptive algorithm for the SCTP that will diminish the frequency of the “false timeouts” and the “false fast retransmits”. These issues both degrade performance and impede the maximum utilization of resources (principally, the bandwidth and the buffers).We call our SCTP protocol extension "RR-SCTP".I Workshop de Arquitecturas, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

Analysis of TCP Performance over a Low-Delay MAC Protocol Designed for Satellite-based Sensor Networks

Advances in terrestrial network technology such as fibre optic cables have significantly increased data rates and reduced cost, making it highly attractive for high-speed data networks. However, satellite communication remains competitive for certain applications where it has clear advantages over other technologies including fibre optic cables. The point to multipoint broadcast capability of a satellite is an important characteristic that allows multiple sub-networks or nodes to be controlled simultaneously by a single transmission. Similarly, multiple sub-networks or nodes can send data to a central point through a common channel, instead of using multiple point-to-point channels. This facilitates implementation of unique supervisory control and data acquisition systems such as a sensor network to monitor oil and gas pipelines or for agricultural purposes. One important problem in design of a satellite data network is how uncoordinated sources can share the common satellite channel. A multiple access control protocol is required to achieve efficient sharing of the channel while meeting the user traffic constraints. This paper investigates effects TCP performance when used with a new low-delay protocol that integrates Random Access and Bandwidth-on-Demand techniques