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

Classifying resilience approaches for protecting smart grids against cyber threats

Smart grids (SG) draw the attention of cyber attackers due to their vulnerabilities, which are caused by the usage of heterogeneous communication technologies and their distributed nature. While preventing or detecting cyber attacks is a well-studied field of research, making SG more resilient against such threats is a challenging task. This paper provides a classification of the proposed cyber resilience methods against cyber attacks for SG. This classification includes a set of studies that propose cyber-resilient approaches to protect SG and related cyber-physical systems against unforeseen anomalies or deliberate attacks. Each study is briefly analyzed and is associated with the proper cyber resilience technique which is given by the National Institute of Standards and Technology in the Special Publication 800-160. These techniques are also linked to the different states of the typical resilience curve. Consequently, this paper highlights the most critical challenges for achieving cyber resilience, reveals significant cyber resilience aspects that have not been sufficiently considered yet and, finally, proposes scientific areas that should be further researched in order to enhance the cyber resilience of SG.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBUA

Characterizing and Improving the Reliability of Broadband Internet Access

In this paper, we empirically demonstrate the growing importance of reliability by measuring its effect on user behavior. We present an approach for broadband reliability characterization using data collected by many emerging national initiatives to study broadband and apply it to the data gathered by the Federal Communications Commission's Measuring Broadband America project. Motivated by our findings, we present the design, implementation, and evaluation of a practical approach for improving the reliability of broadband Internet access with multihoming.Comment: 15 pages, 14 figures, 6 table

Performance of MultiPath TCP on OpenWRT

Multipath TCP (MPTCP) je pokročilým rozšířením stávajícího TCP protokolu, které dokáže nabídnout více než standardní varianta. Transmission Control Protocol (TCP) je dosud nejrozšířenější metodou pro spolehlivou komunikaci přes rozsáhlé sítě. V současné době je protokol TCP omezen na komunikaci pouze jedinou originální cestou mezi zdrojem a cílem, i když je v dané chvíli k dispozici více alternativních cest. TCP nepodporuje multi homing. Tato vlastnost omezuje maximální možný datový tok, protože nelze využívat více linek najednou. MPTCP pomáhá překonat tento nedostatek. Protokol umožňuje rozdělit komunikaci do několika nezávislých TCP spojení a každé z nich může využívat jednu alternativní cestu k cíli komunikace. Díky tomu dokáže MPTCP zvýšit rychlost připojení, rovnoměrně rozdělovat zátěž mezi několik různých připojení k internetu a zároveň pomáhá udržet spojení i v případě výpadku některé z linek. V této práci budou vysvětleny rozdíly mezi MPTCP a TCP protokoly a zároveň jak MPTCP funguje. Dále bude podrobněji vysvětlen způsob jak zkompilovat linuxové jádro s podporou MPTCP v kombinaci se Shadowsocks pro operační systém LEDE. V další části práce bude navržena sada experimentů, které otestují vlastnosti MPTCP z hlediska datové propustnosti, přenosu velkých bloků dat, reakce na zvýšené komunikační zpoždění a reakce na zvýšenou ztrátovost komunikační linky. Hlavním cílem práce je analyzovat a vyhodnotit výkonnost MPTCP oproti TCP v operačním systému OpenWRT.Multipath TCP (MPTCP) is an advanced development of TCP/IP network which has better features when compared to TCP. Transmission Control Protocol (TCP) is the so far widely used method for data transfer and communication over network. Currently, TCP communication is limited to a single path which means no matter how many paths are available, data is transmitted only through single path at once from the source to the destination. TCP does not support multi homing. This feature restricts the use of bandwidth over the network. MPTCP is an evolution of TCP that supports multi homing which transmits data over multiple paths. Data transfer over multiple paths is achieved by distributing data over several TCP subows. Therefore, MPTCP provides better throughput, load balancing among available paths and better handling of network failure. In this thesis, I explain about the dierence between TCP and MPTCP, and how MPTCP works. I also explained in detail about MPTCP enabled Kernel patch along with Shadowsocks in LEDE (OpenWrt). Various experiments are carried out based on bandwidth, delay, loss and bulk data transfer to analyze the performance of MPTCP over TCP. The main goal of this thesis is to identify the performance analysis of MPTCP over normal TCP connection in OpenWRT

Modelling and Design of Resilient Networks under Challenges

Communication networks, in particular the Internet, face a variety of challenges that can disrupt our daily lives resulting in the loss of human lives and significant financial costs in the worst cases. We define challenges as external events that trigger faults that eventually result in service failures. Understanding these challenges accordingly is essential for improvement of the current networks and for designing Future Internet architectures. This dissertation presents a taxonomy of challenges that can help evaluate design choices for the current and Future Internet. Graph models to analyse critical infrastructures are examined and a multilevel graph model is developed to study interdependencies between different networks. Furthermore, graph-theoretic heuristic optimisation algorithms are developed. These heuristic algorithms add links to increase the resilience of networks in the least costly manner and they are computationally less expensive than an exhaustive search algorithm. The performance of networks under random failures, targeted attacks, and correlated area-based challenges are evaluated by the challenge simulation module that we developed. The GpENI Future Internet testbed is used to conduct experiments to evaluate the performance of the heuristic algorithms developed

Building the Future Internet through FIRE

The Internet as we know it today is the result of a continuous activity for improving network communications, end user services, computational processes and also information technology infrastructures. The Internet has become a critical infrastructure for the human-being by offering complex networking services and end-user applications that all together have transformed all aspects, mainly economical, of our lives. Recently, with the advent of new paradigms and the progress in wireless technology, sensor networks and information systems and also the inexorable shift towards everything connected paradigm, first as known as the Internet of Things and lately envisioning into the Internet of Everything, a data-driven society has been created. In a data-driven society, productivity, knowledge, and experience are dependent on increasingly open, dynamic, interdependent and complex Internet services. The challenge for the Internet of the Future design is to build robust enabling technologies, implement and deploy adaptive systems, to create business opportunities considering increasing uncertainties and emergent systemic behaviors where humans and machines seamlessly cooperate

Building the Future Internet through FIRE

The Internet as we know it today is the result of a continuous activity for improving network communications, end user services, computational processes and also information technology infrastructures. The Internet has become a critical infrastructure for the human-being by offering complex networking services and end-user applications that all together have transformed all aspects, mainly economical, of our lives. Recently, with the advent of new paradigms and the progress in wireless technology, sensor networks and information systems and also the inexorable shift towards everything connected paradigm, first as known as the Internet of Things and lately envisioning into the Internet of Everything, a data-driven society has been created. In a data-driven society, productivity, knowledge, and experience are dependent on increasingly open, dynamic, interdependent and complex Internet services. The challenge for the Internet of the Future design is to build robust enabling technologies, implement and deploy adaptive systems, to create business opportunities considering increasing uncertainties and emergent systemic behaviors where humans and machines seamlessly cooperate