The mobile telecommunication industry is undergoing continuous evolution to cope with ever increasing service requirements and expectations of end users. This has recently led to the rise of Mobile Network Aggregators (MNAs), a new type of global virtual operators that deliver mobile communication services by utilizing multiple Mobile Network Operators (MNOs), dynamically connecting to the one that best meets their customers’ needs based on location and time. MNAs can then offer optimized global coverage by connecting to local MNOs that have limited (e.g., national) geographic service. In this paper, we provide a first in-depth analysis of the operations of three major MNAs: Google Fi, Twilio, and Truphone. We conduct performance measurements across these MNAs for critical applications spanning DNS, web browsing, and video streaming, and compare their performance against that of a traditional MNO from two very diverse geographical locations, US and Spain. We find that MNAs may introduce some delay compared to local MNOs in the region where the user is roaming, yet they offer significant performance improvements over the traditional MNOs roaming model, such as home-routed roaming. To fully assess the potential benefits of the MNA model, we also carry out emulation studies assessing the potential performance gains that MNAs could achieve by deploying both control and user plane functions of open-source 5G implementations across different Amazon Web Services locations.

In this paper, we study the effect of reducing the use of BGP’s MRAI mechanism in the Internet. MRAI stands for Minimum Route Advertisement Interval and it is a timer that rate-limits BGP route announcements. In particular, we look into the effects of MRAI removal by simulating router topologies representing all the Autonomous Systems (ASes) in the Internet. We consider the two main MRAI implementation flavors, namely per-session and out-delay MRAI. Reducing the fraction of MRAI-enabled ASes is positive in terms of convergence performance, until the adoption reaches 10% of Internet ASes. Below this threshold, the number of messages exchanged when routes are removed sharply increases, and thus the router load. Depending on the time that it takes for routers to process BGP messages, further reductions in the fraction may even increase convergence time for removing a route. We show that keeping MRAI enabled in few highly connected ASes, the tier-1 ASes, provides some protection against the increase in the computing demand of the routers.

LEDBAT++ is a congestion-control algorithm that implements a less-than-best-effort transport service. In this paper we present rLEDBAT, a purely receiver-based mechanism to implement LEDBAT++ for TCP. rLEDBAT enables a receiver to select some incoming traffic as less-than-best-effort, managing the capacity of the downlink. We describe the different mechanisms composing rLEDBAT that enable the execution of the LEDBAT++ congestion control algorithm at the receiver. We have implemented and experimentally tested rLEDBAT. We validate that the mechanisms incorporated by rLEDBAT at the receiver are indeed effective to implement a less-than-best-effort transport service at the receiver, as it performs similarly to the original sender-based LEDBAT++.

A new model of global virtual Mobile Network Operator (MNO) - the Mobile Network Aggregator (MNA) - has recently been gaining significant traction. MNAs provide mobile communications services to their customers by leveraging multiple MNOs, and connecting through the one that best match their customers' needs at any point in time (and space). MNAs naturally provide optimized global coverage by connecting through local MNOs across the different geographic regions they provide service. In this paper, we dissect the operations of three MNAs, namely, Google Fi, Twilio and Truphone. We perform measurements using the three selected MNAs to assess their performance for three major applications, namely, DNS, web browsing and video streaming. We benchmark their performance comparing it to the one of a traditional MNO. We find that even MNAs provide some delay penalty compared to the service accessed through the local MNOs in the geographic area where the user is roaming, they can significantly improve performance compared to traditional roaming model of the MNOs (e.g. home routed roaming). Finally, in order to fully quantify the potential benefits that can be realized using the MNA model, we perform a set of emulations by deploying both control and user plane functions of open-source 5G implementations in different locations of AWS, and measure the potential gains.

LEDBAT++ is the evolution of LEDBAT, a congestion control algorithm originally designed to provide less-than-best-effort transport on the Internet. LEDBAT++ aims to address a number of shortcomings present in LEDBAT, including late-comer advantage, latency drift, competition on equal grounds with best effort traffic in the presence of small buffers and difficulties experienced while measuring the variations on the delay. In this paper, we perform an experimental evaluation of LEDBAT++ using the Windows Server’s LEDBAT++ implementation. We find that while LEDBAT++ overcomes all the limitations identified in LEDBAT, the change introduced in LEDBAT++ to do so results in a performance penalty that prevents LEDBAT++ flows to seize all the available capacity when there is no competing traffic. We propose two simple modifications to the LEDBAT++ algorithm that would address the identified issues and reduce the penalty.

We present a study of the interaction between two recent congestion control algorithms, LEDBAT++ and BBR. LEDBAT++ is a less-than-best-effort congestion control mechanism and BBR is model-based congestion control algorithm that aims to implement a best-effort traffic class. Naturally, the expectation is that LEDBAT++ yields in front of BBR. While we observe that this is the case in networks with moderate size buffer and when the base RTT is larger than 60 ms, we find that in other common conditions (base RTT smaller than 60 ms and moderate size network buffers), the interaction between LEDBAT++ and BBR is not as expected, as LEDBAT++ fails to yield in front of BBR. The observed behavior is different for the two existent versions of BBR. Specifically, LEDBAT++ competes in equal grounds against BBRv1, and BBRv2 yields in front of LEDBAT++. The BBRv2/LEDBAT++ interaction is exactly the opposite to the desired outcome. We present a number of experiments in diverse conditions that support our conclusions.

Route leak events have historically caused many wide-scale disruptions on the Internet. Leaks are particularly hard to detect because they most frequently involve routes with legitimate origin announced through legitimate paths that are propagated beyond their legitimate scope. In this paper we present ASIRIA, a mechanism for detecting and avoiding leaked routes and protecting against leakage events that uses AS relationship information inferred from the Internet Routing Registries. By relying on existing information, ASIRIA provides immediate benefits to early adopters. In particular, we consider the deployment of ASIRIA to detect leaks caused by over 300 ASes and we show that it can detect over 99% of the leakage events generated by a customer or a peer solely using currently available information in 90% of the cases.

In this paper we present a large measurement study of the impact on the performance of the adoption of HTTPS as a transport for the DNS protocol (DoH) with public resolvers compared to the existent approach of using non-encrypted transport of DNS queries with the resolver services locally provided by ISPs. Using on web-ads as the mean to execute our tests, we perform over 42 million measurements from more than 4 million vantage points distributed in 32 countries and served by over 2,500 ISPs. We find that, the median resolution time increased 17 ms when using DoH with Cloudflare, 41 ms when using DoH with Quad9, 68 ms when using DoH with Google and 170 ms when using DoH with DNS.SB, compared to using Do53 with the local resolver for a non-cached name. We find similar increases even when using caching. The results presented in the paper contribute to the ongoing discussion of the tradeoffs involved in the combined adoption of public resolvers and DoH.

“Roam like Home” is the initiative of the European Commission (EC) to end the levy of extra charges when roaming within the European region. As a result, people can use data services more freely across Europe. However, the implications of roaming solutions on network performance have not been carefully examined yet. This paper provides an in-depth characterization of the implications of international data roaming within Europe. We build a unique roaming measurement platform using 16 different mobile networks deployed in six countries across Europe. Using this platform, we measure different aspects of international roaming in 4G networks in Europe, including mobile network configuration, performance characteristics, and quality of experience. We find that operators adopt a common approach to implement roaming called Home-routed roaming (HR). This results in additional latency penalties of 60 ms or more, depending on geographical distance. This leads to worse browsing performance, with an increase in the metrics related to Quality of Experience (QoE) of users (Page Load time and Speed Index) in the order of 15-20 percent. We further analyze in isolation the impact of latency on QoE metrics and find that the penalty imposed by HR leads to a degradation on QoE metrics up to 150 percent in case of intercontinental roaming.

IP Exchange Providers (IPX-Ps) offer to their customers (e.g., mobile or IoT service providers) global data roaming and support for a variety of emerging services. They peer to other IPX-Ps and form the IPX network, which interconnects 800 MNOs worldwide offering their customers access to mobile services in any other country. Despite the importance of IPX-Ps, little is known about their operations and performance. In this paper, we shed light on these opaque providers by analyzing a large IPX-P with more than 100 PoPs in 40+ countries, with a particularly strong presence in America and Europe. Specifically, we characterize the traffic and performance of the main infrastructures of the IPX-P (i.e., 2-3-4G signaling and GTP tunneling), and provide implications for its operation, as well as for the IPX-P's customers. Our analysis is based on statistics we collected during two time periods (i.e., prior and during COVID-19 pandemic) and includes insights on the main service the platform supports (i.e., IoT and data roaming), traffic breakdown and geographical/temporal distribution, communication performance (e.g., tunnel setup time, RTTs). Our results constitute a step towards advancing the understanding of IPX-Ps at their core, and provide guidelines for their operations and customer satisfaction.

Network resource management relies on trusted infrastructures. However, current trusted infrastructures have centralized or hierarchical structures where root nodes often have privileges over subtrees. Hacked or malicious roots may affect subtrees by modifying IP ownership, routing and so on. Therefore, a trusted and decentralized network resource management becomes crucial. The emergence of blockchain such as Ethereum becomes a leading candidate for achieving trusted and decentralized network resource management. In this paper, based on Ethereum, we design a trusted authentication scheme that includes voting policy, endorsement, credibility model and rebinding mechanism to ensure the credibility of entities. Our scheme can allocate, delegate and transfer network resources in a trusted and decentralized style. The experimental results verify the feasibility and security of our scheme. When an entity is hacked or malicious, its endorsement authentication is revoked and the entity does not have the right to manage the network resources. In addition, the overhead increased by the trusted authentication scheme is within a reasonable range.

During early 2020, the SARS-CoV-2 virus rapidly spread worldwide, forcing many governments to impose strict lock-down measures to tackle the pandemic. This significantly changed peoples mobility and habits, subsequently impacting how they use telecommunication networks. In this paper, we investigate the effects of the COVID-19 emergency on a UK Mobile Network Operator (MNO). We quantify the changes in users mobility and investigate how this impacted the cellular network usage and performance. Our analysis spans from the entire country to specific regions, and geodemographic area clusters. We also provide a detailed analysis for London. Our findings bring insights at different geotemporal granularity on the status of the cellular network, from the decrease in data traffic volume in the cellular network and lower load on the radio network, counterposed to a surge in the conversational voice traffic volume.

BGP reconvergence events involving a large number of prefixes may result in the loss of large amounts of traffic. Based on the observation that a very small number of prefixes carries the vast majority of traffic, we propose Power Prefixes Prioritization (PPP) to ensure the routes of these popular BGP prefixes converge first. By doing so, we significantly reduce the amount of traffic lost during reconvergence events. To achieve this, PPP obtains an ordered list of popular prefixes through traffic inspection, and configures the resulting prefix rank in the BGP routers to prioritize the processing and advertisement of BGP routes. We model the benefits of PPP over traditional BGP processing in terms of traffic loss for both generic and a Zipf traffic distribution, and we consider the impact of sampling in the process of obtaining the prefix rank. Applying the mechanism to real traffic traces obtained from WIDE, we show that PPP reduces the amount of traffic lost by an order of magnitude, even when we configure it to use conservative sampling rates. We prototype our proposal in Quagga to show the feasibility of its implementation, and we observe similar traffic loss reduction. PPP can be deployed incrementally, as it is implemented purely as a change in the router-internal BGP processing behavior.

"Roam like Home" is the initiative of the European Commission (EC) to end the levy of extra charges when roaming within the European region. As a result, people are able to use data services more freely across Europe. However, the implications roaming solutions have on performance have not been carefully examined. This paper provides an in-depth characterization of the implications of international data roaming within Europe. We build a unique roaming measurement platform using 16 different mobile networks deployed in six countries across Europe. Using this platform, we measure different aspects of international roaming in 3G and 4G networks, including mobile network configuration, performance characteristics, and content discrimination. We find that operators adopt common approaches to implementing roaming, resulting in additional latency penalties of ∼60 ms or more, depending on geographical distance. Considering content accessibility, roaming poses additional constraints that leads to only minimal deviations when accessing content in the original country. However, geographical restrictions in the visited country make the picture more complicated and less intuitive.

In this paper, we propose the BGP Visibility Toolkit, a system for detecting and analyzing anomalous behavior in the Internet. We show that interdomain prefix visibility can be used to single out cases of erroneous demeanors resulting from misconfiguration or bogus routing policies. The implementation of routing policies with BGP is a complicated process, involving fine-tuning operations and interactions with the policies of the other active ASes. Network operators might end up with faulty configurations or unintended routing policies that prevent the success of their strategies and impact their revenues. As part of the Visibility Toolkit, we propose the BGP Visibility Scanner, a tool which identifies limited visibility prefixes in the Internet. The tool enables operators to provide feedback on the expected visibility status of prefixes. We build a unique set of ground-truth prefixes qualified by their ASes as intended or unintended to have limited visibility. Using a machine learning algorithm, we train on this unique dataset an alarm system that separates with 95% accuracy the prefixes with unintended limited visibility. Hence, we find that visibility features are generally powerful to detect prefixes which are suffering from inadvertent effects of routing policies. Limited visibility could render a whole prefix globally unreachable. This points towards a serious problem, as limited reachability of a non-negligible set of prefixes undermines the global connectivity of the Internet. We thus verify the correlation between global visibility and global connectivity of prefixes.

In this paper, we propose the use of prefix visibility at the interdomain level as an early symptom of anomalous events in the Internet. We focus on detecting anomalies which, despite their significant impact on the routing system, remain concealed from state of the art tools. We design a machine learning system to winnow the prefixes with unintended limited visibility - symptomatic of anomalous events - from the prefixes with intended limited visibility - resulting from legitimate routing operations. We train a winnowing algorithm with ground-truth data on 20,000 operational limited visibility prefixes (LVPs) already classified by the operators of the origin networks. The ground-truth was collected using the BGP Visibility Scanner, a tool we developed to provide operators with a multi-angle view on the efficacy of their routing policies. We build a dataset with the pre-classified prefixes and the features describing their visibility status dynamics. We further use this dataset to derive a boosted decision tree which winnows unintended LVPs with an accuracy of 95%.

By tweaking the BGP configurations, the network operators are able to express their interdomain routing preferences, designed to accommodate a myriad goals. Given the complex interactions between policies in the Internet, the origin AS by itself cannot ensure that only by configuring a routing policy it can also achieve the anticipated results. Moreover, the definition of routing policies is a complicated process, involving a number of subtle tuning operations prone to errors. In this paper, we propose the BGP Visibility Scanner which allows network operators to validate the correct implementation of their routing policies, by corroborating the BGP routing information from approximatively 130 independent observation points in the Internet. We exemplify the use of the proposed methodology and also perform an initial validation for the BGP Visibility Scanner capabilities through various real operational use cases.

Over the last years, the research community has been deeply concerned about the scalability issues that the Internet routing is facing. In this paper we study the economic incentives for the Global Routing Table (GRT) explosive growth by considering a commons model in which the GRT is a public resource. In particular, we analyze the motivations the ASes have for deaggregating their assigned address blocks. We evaluate the efficiency of the global routing system, the properties of the game equilibria and we examine its relation to the social welfare point of the considered game setup. We prove that the GRT, just like any common natural resource, "remorselessly generates tragedy", following Hardin's game theoretic analysis on the tragedy of the commons. Finally, we introduce in the model a pricing mechanism that aims to avoid the tragedy of the Internet routing commons.

Normal TCP/IP operation is for the routing system to select a best path that remains stable for some time, and for TCP to adjust to the properties of this path to optimize throughput. By executing TCP's congestion control algorithms on multiple paths at the same time, a multipath TCP can shift its traffic to a less congested path, thus maximizing both the throughput for the multipath TCP user and leaving more capacity available for other traffic on more congested paths. And when a path fails, this can be detected and worked around by multipath TCP much more quickly than by waiting for the routing system to repair the failure. This paper proposes a one-ended multipath TCP that is implemented on the sending host only, without requiring modifications on the receiving host, for the purposes of maximizing performance in transmissions from multiply connected large servers towards singly connected end-users and recovering from failures more quickly.

The aviation community is in the process of designing the next generation Aeronautical Telecommunications Network (ATN), based on Internet standards, to provide air- ground communications for the aircraft. Support for mobile networks in the current Internet architecture is provided by the NEtwork Mobility (NEMO) protocol. As currently defined, NEMO Basic Support protocol lacks of Route Optimization support which is an essential requirement for its adoption as part of the next generation ATN. This paper presents a novel security tool, the Crypto Prefixes, and their application to the Route Optimization in Nemo (CRYPTRON). The Crypto Prefixes are IPv6 prefixes with embedded cryptographic information that enable the Mobile Network Prefix proof-of ownership without any centralized trust infrastructure. In CRYPTRON, the Crypto Prefixes are used to protect the establishment of the bindings on the Correspondent Nodes for the whole Mobile Network Prefix.

This paper characterizes analytically the performance of REAchability Protocol (REAP), a network layer end-to-end recovery protocol for IPv6. REAP was developed by the IETF SHIM6 Working Group as part of its multihoming solution. The behavior of REAP is governed by a small number of parameters: three timers, a simple characterization of the application traffic, and the communication delay. The key figure of merit of REAP performance is the time to recover from a path failure as seen by the upper layers, figure that cannot be trivially obtained, despite the apparent simplicity of this reachability protocol. In this paper we provide upper bounds for the recovery time of REAP for different deployment scenarios, applying these analytical results to two interesting case studies, TCP and VoIP traffic.

We present an architecture for the provision of network layer privacy based on the SHIM6 multihoming protocol. In its basic form, the architecture prevents on-path eavesdroppers from using SHIM6 network layer information to correlate packets that belong to the same communication but use different locators. To achieve this, several extensions to the SHIM6 protocol and to the HBA (Hash Based Addresses) addressing model are defined. On its full-featured mode of operation, hosts can vary dynamically the addresses of the packets of on-going communications. Single-homed hosts can adopt the SHIM6 protocol with the privacy enhancements to benefit from this protection against information collectors.

An important requirement for Internet protocol (IP) networks to achieve the aim of ubiquitous connectivity is network mobility (NEMO). With NEMO support we can provide Internet access from mobile platforms, such as public transportation vehicles, to normal nodes that do not need to implement any special mobility protocol. The NEMO basic support protocol has been proposed in the IETF as a first solution to this problem, but this solution has severe performance limitations. This paper presents MIRON: Mobile IPv6 route optimization for NEMO, an approach to the problem of NEMO support that overcomes the limitations of the basic solution by combining two different modes of operation: a Proxy-MR and an address delegation with built-in routing mechanisms. This paper describes the design and rationale of the solution, with an experimental validation and performance evaluation based on an implementation

It is expected that IPv6 multihomed sites will obtain as many global prefixes as direct providers they have, so traffic engineering techniques currently used in IPv4 multihomed sites is no longer suitable. However, traffic engineering is required for several reasons, and in particular, for being able to properly support multimedia communications. In this paper we present a framework for traffic engineering in IPv6 multihomed sites with multiple global prefixes. Within this framework, we have included several tools such as DNS record manipulation and proper configuration of the policy table defined in RFC 3484. To provide automation in the management of traffic engineering, we analyzed the usage of two mechanisms to configure the policy table.

The network mobility (NEMO) basic support protocol enables mobile networks to change their point of attachment to the Internet, while preserving established sessions of the nodes within the mobile network. When only a nonnested mobile network is considered, the so-called triangle routing is the main problem that should be faced. In mobile IPv6, the route optimisation mechanism solves this problem, and the return routability mechanism aims to limit the security concerns originated because of the route optimisation. Nowadays return routability is considered a weak solution (i.e., based on strong assumptions). In this article we explore different approaches to route optimisation in NEMO and we devise how to adapt some of the terminal mobility solutions to a NEMO environment, where, as we propose, a delegation of signalling rights from the mobile network node to the mobile router is necessary.