ECF: An MPTCP path scheduler to manage heterogeneous paths

© 2017 ACM. Multi-Path TCP (MPTCP) is a new standardized transport protocol that enables devices to utilize multiple network interfaces. The default MPTCP path scheduler prioritizes paths with the smallest round trip time (RTT). In this work, we examine whether the default MPTCP path scheduler can provide applications the ideal aggregate bandwidth, i.e., the sum of available bandwidths of all paths. Our experimental results show that heterogeneous paths cause under-utilization of the fast path, resulting in undesirable application behaviors such as lower video streaming quality than can be obtained using the available aggregate bandwidth. To solve this problem, we propose and implement a new MPTCP path scheduler, ECF (Earliest Completion First), that utilizes all relevant information about a path, not just RTT. Our results show that ECF consistently utilizes all available paths more efficiently than other approaches under path heterogeneity, particularly for streaming video

Managing Path Switching in Multipath Video Streaming

Video streaming has become the major source of Internet traffic nowadays. Considering that content delivery network providers utilize Video over Hypertext Transfer Protocol/Transmission Control Protocol (HTTP/TCP) as the preferred protocol stack for video streaming, understanding TCP performance in transporting video streams has become paramount. Recently, multipath transport protocols have allowed video streaming over multiple paths to become a reality. In this paper, we analyze the impact of path switching on multipath video streaming and network performance, and propose new schedulers which minimize the number of path switching. We utilize network performance measures, as well as video quality metrics, to characterize the performance and interaction between network and application layers of video streams for various network scenarios.The Eleventh International Conference on Evolving Internet (INTERNET 2019), June 30 to July 04, 2019, Rome, Ital

Um escalonador de pacotes para o protocolo MPQUIC apoiado na similaridade dos caminhos

Orientador: Michele Nogueira LimaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa : Curitiba, 16/09/2019Inclui referências: p. 73-79Área de concentração: Ciência da ComputaçãoResumo: Os servicos Web evoluiram significativamente desde o seu inicio no final dos anos 80. Ao longo dos anos, estes servicos aumentaram em numero, tamanho e complexidade. Alem disso, novos servicos como aqueles de streaming, os jogos online e a realidade virtual demandam cada vez mais recursos devido as exigencias dos usuarios e a concorrencia entre as plataformas que disponibilizam estes servicos. Em geral, estes servicos sao sensiveis as falhas e a latencia da rede. Garantir a entrega de pacotes de maneira confiavel e uma das principais funcoes da camada de transporte. Contudo, os protocolos de transporte dominantes na Internet, como o protocolo TCP e UDP, possuem limitacoes e sao dificeis de serem atualizados, justamente pela sua alta utilizacao. Em face disso, a empresa Google desenvolveu o protocolo de transporte QUIC (Quick UDP Internet Connection) e um grupo de trabalho do IETF trata da sua padronizacao. O protocolo QUIC e fundamentado no protocolo UDP e sua proposta e substituir o conjunto de protocolos da Web formado pelos protocolos HTTP/TLS/TCP. O protocolo QUIC traz beneficios ao reduzir a latencia da conexao por se abster do processo de estabelecimento de conexao (three-way handshake) na maioria de suas conexoes, alem de aumentar a seguranca durante a comunicacao ao criptografar todos os seus pacotes e parte das informacoes contidas no cabecalho de seus segmentos. Em pesquisas realizadas pela empresa Google, o protocolo QUIC diminui 3% o tempo medio de carregamento na pagina de pesquisa da empresa, quando comparado ao protocolo TCP. Contudo, estes valores tendem a crescer com o uso simultaneo das multiplas interfaces de rede disponiveis nos dispositivos dos usuarios. Visando a este objetivo, outro grupo de trabalho do IETF impulsiona o desenvolvimento do protocolo QUIC sobre multicaminhos. O protocolo QUIC Multicaminhos (MPQUIC) apresenta vantagem no uso das multiplas interfaces de rede disponiveis com o intuito de aumentar o desempenho e a disponibilidade dos servicos. Entretanto, o uso de varios caminhos simultaneamente resulta em desafios relacionados a diversidade e a heterogeneidade da rede. Um desses desafios e a entrega de pacotes fora de ordem (ou o problema de reordenamento), que ocorre devido a estas adversidades. As abordagens na literatura destinadas a mitigacao do problema de reordenamento, direcionam suas propostas ao escalonador de pacotes, que e um dos principais componentes dos protocolos multicaminhos e emprega um importante papel no desempenho da transmissao, pois ele e o responsavel pela selecao e alocacao de dados nos diferentes caminhos disponiveis para a comunicacao entre cliente e servidor. Sendo assim, este trabalho apresenta o escalonador STOUT (do ingles, Similarity againsT packets OUT-of-order) que visa reduzir os efeitos da heterogeneidade dos caminhos ao seleciona-los baseando-se na similaridade de suas caracteristicas. Em testes realizados, o escalonador STOUT demonstrou melhor desempenho quando comparado ao escalonador padrao do protocolo MPQUIC, alem de diminuir o tempo em que os pacotes aguardam para reordenacao. Palavras-chave: Transmissao Multicaminhos, Escalonador, MPQUIC, QUIC, Reordenamento de Pacotes, DesempenhoAbstract: Web services have evolved significantly since their conception in the late 1980s. Over the years, these services have increased in number, size and complexity. In addition, new services, such as streaming services, online games, and virtual reality, are increasingly demanding resources due to user requests and competition among the platforms that provide these services. In general, these services are sensitive to network failures and latency. Ensuring reliable delivery of packages is one of the key functions of the transport layer. However, dominant Internet transport protocols, such as the TCP and UDP protocol, have limitations and are difficult to be updated due to their high utilization. Given these facts, Google has developed Quick UDP Internet Connection (QUIC) transport protocol and an IETF working group addresses its standardization. The QUIC protocol is based on the UDP protocol and its purpose is to replace the web protocol set formed by the HTTP/TLS/TCP protocols. The QUIC protocol has benefits in reducing connection latency by refraining from the three-way-handshake process on most of your connections, as well as increasing security during communication by encrypting all your connections, packets and part of the information contained in the header of their segments. In researches by Google, the QUIC protocol decreases the average load time on the company's search page by 3% compared to the TCP protocol. However, these values tend to grow with the simultaneous use of multiple network interfaces available on user devices. Towards this end, another IETF working group drives the development of the multipath QUIC protocol. The multipath QUIC (MPQUIC) protocol has the advantage of using the multiple network interfaces available to increase performance and service availability. However, using multiple paths simultaneously results in challenges related to network diversity and heterogeneity. One of these challenges is the delivery of out-of-order packages (or the reordering problem), which occurs because of these adversities. Approaches in the literature aimed at mitigating the reordering problem directing their proposals to the packet scheduler, which is a major component of multipath protocols and plays an important role in transmission performance as it is responsible for data selection and allocation through different paths available for client-server communication. Thus, this work presents the scheduler named Similarity againsT packets OUT-of-order (STOUT) which aims to reduce the effects of path heterogeneity by selecting them based on the similarity of their characteristics. In tests performed, the STOUT scheduler has shown better performance compared to the standard MPQUIC protocol scheduler, as well as decreasing the time packets wait for reordering. Keywords: Multipath Transmission, Scheduler, MPQUIC, QUIC, Packet Reordering, Performanc

Soluções Alternativas de Escalonamento e Gerenciamento de Caminhos para o MPTCP.

O MultiPath TCP (MPTCP) é um conjunto de extensões para o protocolo TCP que viabiliza a transmissão confiável sobre múltiplos caminhos fim-a-fim entre cliente e servidor na Internet. Dois benefícios são imediatamente obtidos com o protocolo: i) o aumento da vazão fim-a-fim através da agregação da transmissão por múltiplos sub-fluxos TCP; ii) maior tolerância a falhas de comunicação, uma vez que, na indisponibilidade de um sub-fluxo, há um ou mais sub-fluxos ativos. Neste trabalho, investigamos experimentalmente dois mecanismos internos do MPTCP: escalonamento de pacotes, que determina a escolha do sub-fluxo no momento da transmissão; gerenciamento de caminhos, que determina a forma como os sub-fluxos são estabelecidos. Identificamos problemas de desempenho envolvidos em cada um desses mecanismos e propomos soluções alternativas. O primeiro problema é resultante do escalonamento padrão do MPTCP, Lowest Latency (LL), cujo critério de escolha de sub-fluxo de envio é definido exclusivamente pela menor estimativa dos tempos observados de ida e volta dos pacotes, podendo levar a decisões inconsistentes quando sub-fluxos estão sob perda de pacotes em caminhos congestionados.Em contrapartida ao LL, foi proposto e implementado três escalonadores alternativos – Largest Window Space (LWS), Lowest Time/Space (LTS) e Highest Sending Rate (HSR), que utilizam parâmetros mais confiáveis para construir critérios de decisão mais consistentes. O segundo problema está envolvido com o gerenciador de caminhos padrão do MPTCP, denominado Full-mesh, que estabelece um número excessivo de sub-fluxos, gerando concorrência entre próprios sub-fluxos que compartilham um mesmo caminho fim-a-fim e, consequentemente, limitando a vazão fim-a-fim. Para solucionar esse problema, foi proposto e implementado um novo gerenciador de caminhos – Single-mesh, que é capaz de mitigar o congestionamento intercaminho, aumentando a taxa de transmissão dos sub-fluxos em caminhos não congestionados. Um ambiente experimental foi implantado em laboratório e, então, projetado e realizado experimentos exaustivos para avaliar as soluções propostas. Em grande parte dos experimentos, foram obtidos resultados satisfatórios, de melhor desempenho, ao comparar as soluções propostas com as soluções padrão existentes no MPTCP. Em caminhos de capacidades heterogêneas e maiores taxas de perda de pacotes, as soluções alternativas de escalonamento proporcionaram ganhos de até 7% na vazão fim-a-fim em comparação ao LL, inclusive sobre diferentes mecanismos de controle de congestionamento do MPTCP. O gerenciamento de Single-mesh mostrou ser eficiente para alguns controles de congestionamento, obtendo mais que o dobro na vazão de Full-mesh sobre caminhos de capacidade heterogênea não congestionados

ResTP: A Configurable and Adaptable Multipath Transport Protocol for Future Internet Resilience

Motivated by the shortcomings of common transport protocols, e.g., TCP, UDP, and MPTCP, in modern networking and the belief that a general-purpose transport-layer protocol, which can operate efficiently over diverse network environments while being able to provide desired services for various application types, we design a new transport protocol, ResTP. The rapid advancement of networking technology and use paradigms is continually supporting new applications. The configurable and adaptable multipath-capable ResTP is not only distinct from the standard protocols by its flexibility in satisfying the requirements of different traffic classes considering the characteristics of the underlying networks, but by its emphasis on providing resilience. Resilience is an essential property that is unfortunately missing in the current Internet. In this dissertation, we present the design of ResTP, including the services that it supports and the set of algorithms that implement each service. We also discuss our modular implementation of ResTP in the open-source network simulator ns-3. Finally, the protocol is simulated under various network scenarios, and the results are analyzed in comparison with conventional protocols such as TCP, UDP, and MPTCP to demonstrate that ResTP is a promising new transport-layer protocol providing resilience in the Future Internet (FI)

On Leveraging Multi-Path Transport in Mobile Networks

Multi-Path TCP (MPTCP) is a new transport protocol that enables mobile devices to simultaneously use several physical paths through multiple network interfaces. MPTCP is particularly useful for mobile devices, which usually have multiple wireless interfaces such as IEEE 802.11 (WiFi), cellular (3G/LTE), and Bluetooth. However, applying MPTCP to mobile devices introduces new concerns since they operate in harsh environments with resource constraints due to intermittent path availability and limited power supply. The goal of this thesis is to resolve these problems so as to be able to practically deploy MPTCP in mobile devices. The first part of the thesis develops a cross-layer path management approach that exploits information from the physical and medium access control layers to deal with intermittent path availability in mobile environment while increasing path utilization of MPTCP over lossy links. Experimental results show that this approach efficiently utilizes intermittently available WiFi paths, with throughput improvements of up to 72%. In addition to the need to manage intermittent path availability, MPTCP must deal with the increased energy consumption due to simultaneous operation of multiple network interfaces. Hence, it is important to understand the energy consumption behavior to deploy MPTCP in mobile devices. We develop an energy model for MPTCP power consumption derived from experimental measurements. Experimental results show that the model accurately estimates the MPTCP energy consumption. Based on the MPTCP energy model, we further explore conditions under which MPTCP is more energy-efficient than either standard TCP or MPTCP. Informed by this finding, we design and implement an energy-aware MPTCP variant for mobile devices. Experimental results show that our approach reduces power consumption compared to standard MPTCP by up to 80% for small file downloads and up to 15% for large file downloads, while preserving the availability and robustness benefits of MPTCP. Finally, we study the impact of path asymmetry on MPTCP performance. Since path asymmetries frequently appear in mobile networks, it is crucial to design a MPTCP path scheduler that properly distributes traffic across available paths, which has different network characteristics such as round-trip time and bandwidth. We propose and implement a new MPTCP path scheduler, ECF (Earliest Completion First), that utilizes all relevant information about a path. Experimental results show that in the presence of path asymmetries ECF consistently utilizes all available paths more efficiently while mitigating out-of-order delay compared to the default scheduler

Revisiting the IETF multipath extensions on transport layer

Load sharing on the transport layer of the OSI reference model is an important topic in the IETF standardization. This approach is also supported by the industry to optimize the use of the resources in a network like the Internet. After many trials, two basic sets of mechanisms and functionalities on the transport layer have been proposed by the IETF to achieve load sharing. These basic sets extend the protocol mechanisms that were originally designed for the use in singlepath dominated networks and represent only a first step to introduce a real end-to-end multipath transfer on the Internet. These first basic sets must be investigated and improved for the next steps. The Transmission Control Protocol (TCP) and the Stream Control Transmission Protocol (SCTP) provide the basis for the two IETF end-to-end multipath extensions. Both singlepath transport protocols have a different historical background but similar goals. These can be characterized by a reliable, connection-oriented and ordered data transport. However, initial experiments with the IETF multipath extensions in real networks show unexpected and in some cases clearly inadequate results. It is becoming rather apparent that the singlepath transport protocol specifications with their singlepath goals have a significant impact on the effectiveness of the load sharing mechanism and, furthermore, that the severity of the influence depends on the topology. The new mechanisms for multipath transfer include, in particular, an extended “path management” and “scheduling” task. The mechanisms addressing the path management organize the new, alternative paths and the scheduling mechanisms sup- port their effective use. For both protocol extensions of TCP and SCTP, an interaction can be identified between the new load sharing mechanisms and the existing specifications for singlepath transfer. This thesis systematically identifies the impact factors of the singlepath specifications on the new load sharing mechanisms and demonstrates their effects. In addition to the focus on the optimal use, the fair distribution of resources across all connections must be taken into account in the IETF standardization process. This so-called “fairness” discus- sion is mandatory for a transport protocol in the IETF context and has a direct impact on the overall system performance. Furthermore, this thesis discusses the currently implemented load sharing extensions and analyzes their weaknesses. Moreover, in this work new design approaches are developed to decrease the impact