Presentation of the July 2021 issue of CCR.

This paper presents NemFi: a trace-driven WiFi emulator. NemFi is a record-and-replay emulator that captures traces representing real WiFi conditions, and later replay these traces to reproduce the same conditions. In this paper, we demonstrate that the state-of-the-art emulator that was developed for cellular links cannot emulate WiFi conditions. We identify the three key differences that must be

During the last decade, Machine Learning (ML) has increasingly become a hot topic in the field of Computer Networks and is expected to be gradually adopted for a plethora of control, monitoring and management tasks in real-world deployments. This poses the need to count on new generations of students, researchers and practitioners with a solid background in ML applied to networks. During 2020, the

High level, network programming languages, like P4, enable students to gain hands-on experience in the structure of a switch or router. Students can implement the packet processing pipeline themselves, without prior knowledge of circuit design. However, when choosing a P4 programmable target for use in the classroom, instructors face a lack of options. On the one hand, software solutions, such as the

Limited domains were defined conceptually in RFC 8799 to cater to requirements and behaviours that extend the dominant view of IP packet delivery in the Internet. This paper argues not only that limited domains have been with us from the very beginning of the Internet but also that they have been shaping innovation of Internet technologies ever since, and will continue to do so. In order to build limited

RFC 9000, published in May 2021, marks an important milestone for the Internet's standardization body, the Internet Engineering Task Force (IETF): finally, the specification of the QUIC protocol is available. QUIC is the result of a five-year effort - and it is also the second of two major protocols (the first being SPDY, which later became HTTP/2) that Google LLC first deployed, and then brought to

In January and April 2021 we held the Workshop on Overcoming Measurement Barriers to Internet Research (WOMBIR) with the goal of understanding challenges in network and security data set collection and sharing. Most workshop attendees provided white papers describing their perspectives, and many participated in short-talks and discussion in two virtual workshops over five days. That discussion produced

An earlier study observed that until 2008, the size of the BGP4 system for IPv4 appeared to have grown approximately in proportion to the square root of the host count of the globally addressable Internet. This article revisits this study by including IPv4 data until 2020 and adding IPv6 data. The results indicate that BGP4 for IPv4 is continuing to scale steadily even as IPv4 approaches its end of

This April 2021 issue contains one technical paper as well as five editorial notes.

Switch failures can hamper access to client services, cause link congestion and blackhole network traffic. In this study, we examine the nature of switch failures in the datacenters of a large commercial cloud provider through the lens of survival theory. We study a cohort of over 180,000 switches with a variety of hardware and software configurations and find that datacenter switches have a 98% likelihood

We study operational issues faced by Small and Medium Enterprise (SME) network owners and find that SME network management practices have stagnated over the past decade, despite many recent advances in network management. Many of these advances target hyperscalers and ISPs and cannot be directly applied to SME networks that are operated with vastly different constraints. In our work, we outline these

There is now a significant and growing functional gap between the public Internet, whose basic architecture has remained unchanged for several decades, and a new generation of more sophisticated private networks. To address this increasing divergence of functionality and overcome the Internet's architectural stagnation, we argue for the creation of an Extensible Internet (EI) that supports in-network

On 16-17 December 2020, CAIDA hosted the 11th interdisciplinary Workshop on Internet Economics (WIE) in a virtual Zoom conference. This year our goal was to gather feedback from researchers on their experiences using CAIDA’s data for economics or policy research. We invited all researchers who reported use of CAIDA data in these disciplines. We discussed their successes and challenges of using the

The space industry is moving rapidly towards offering low-latency and high-bandwidth global Internet coverage using low Earth orbit satellites. Such networks represent "one giant leap" in Internet infrastructure, both in their goals and the underlying technology. Due to their unique characteristics, they open up new opportunities, and pose new research challenges. I thus lay out a case for networking

This interview is part of a series on Great Educators in Computer Networking, where we interview some of the most impactful and skilled educators in our field. Here, we interviewed Australian Bruce Davie, the self-described computer scientist/engineer/runner/cyclist, who agreed to talk to us about his thoughts on computer networking education, his role in it, his thoughts about the big ideas in our

This January 2021 issue contains three technical papers as well as two editorial notes.

Networks have become complex systems that combine various concepts, techniques, and technologies. As a consequence, modelling or simulating them now is extremely complicated and researchers massively resort to prototyping techniques. Mininet is the most popular tool when it comes to evaluate SDN propositions. Mininet allows to emulate SDN networks on a single computer but shows its limitations with

Many promising networking research ideas in programmable networks never see the light of day. Yet, deploying research prototypes in production networks can help validate research ideas, improve them with faster feedback, uncover new research questions, and also ease the subsequent transition to practice. In this paper, we show how researchers can run and validate their research ideas in their own backyards---on

Analyzing and interpreting the exact behavior of new delay-based congestion control protocols with complex non-linear control loops is exceptionally difficult in highly variable networks such as cellular networks. This paper proposes a Model-Driven Interpretability (MDI) congestion control framework, which derives a model version of a delay-based protocol by simplifying a congestion control protocol's

Since the beginning of the COVID-19 pandemic, governments introduced several social restrictions. As of 18 March 2020, more than 250 million people were in lockdown in Europe. This drastically increased the number of online activities. Due to this unprecedented situation, some concerns arose about the suitability of the Internet network to sustain the increased usage. Italy was severely hit by the

What if instead of having to implement controversial user tracking techniques, Internet advertising & marketing companies asked explicitly to be granted access to user data by name and category, such as Alice→Mobility→05-11-2020? The technology for implementing this already exists, and is none other than the Information Centric Networks (ICN), developed for over a decade in the framework of Next Generation

This October 2020 issue contains five technical papers, the third paper of our education series, as well as three editorial notes.

In anycast deployments, knowing how traffic will be distributed among the locations is challenging. In this paper, we propose a technique for partitioning the Internet using passive measurements of existing anycast deployments such that all IP addresses within a partition are routed to the same location for an arbitrary anycast deployment. One IP address per partition may then represent the entire

IoT deployments targeting different application domains are being unfolded at various administrative levels such as countries, states, corporations, or even individual households. Facilitating data transfers between deployed sensors and back-end cloud services is an important aspect of IoT deployments. These data transfers are usually done using Low Power WAN technologies (LPWANs) that have low power

The IPX Network interconnects about 800 Mobile Network Operators (MNOs) worldwide and a range of other service providers (such as cloud and content providers). It forms the core that enables global data roaming while supporting emerging applications, from VoLTE and video streaming to IoT verticals. This paper presents the first characterization of this, so-far opaque, IPX ecosystem and a first-of-its-kind

Mobile devices have become the primary mode of Internet access. Yet, differences in mobile hardware resources, such as device memory, coupled with the rising complexity of Web pages can lead to widely different quality of experience for users. In this work, we analyze how device memory usage affects Web browsing performance. We quantify the memory footprint of popular Web pages over different mobile

Quantum computing is threatening current cryptography, especially the asymmetric algorithms used in many Internet protocols. More secure algorithms, colloquially referred to as Post-Quantum Cryptography (PQC), are under active development. These new algorithms differ significantly from current ones. They can have larger signatures or keys, and often require more computational power. This means we cannot

This paper focuses on the K-12 educational activities of COSMOS-Cloud enhanced Open Software defined MObile wireless testbed for city-Scale deployment. The COSMOS wireless reasearch testbed is being deployed in West Harlem (New York City) as part of the NSF Platforms for Advanced Wireless Research (PAWR) program. COSMOS' approach for K-12 education is twofold: (i) create an innovative and concrete

Many countries are deploying Covid-19 contact tracing apps that use Bluetooth Low Energy (LE) to detect proximity within 2m for 15 minutes. However, Bluetooth LE is an unproven technology for this application, raising concerns about the efficacy of these apps. Indeed, measurements indicate that the Bluetooth LE received signal strength can be strongly affected by factors including (i) the model of

Since the start of the COVID-19 pandemic, technology enthusiasts have pushed for digital contact tracing as a critical tool for breaking the COVID-19 transmission chains. Motivated by this push, many countries and companies have created apps that enable digital contact tracing with the goal to identify the chain of transmission from an infected individual to others and enable early quarantine. Digital

Controlling an opaque system by reading some "dials" and setting some "knobs," without really knowing what they do, is a hazardous and fruitless endeavor, particularly at scale. What we need are transparent networks, that start at the top with a high-level intent and map all the way down, through the control plane to the data plane. If we can specify the behavior we want in software, then we can check

This July 2020 issue contains four technical papers, the second paper of our education series, as well as two editorial notes.

Transport Layer Security (TLS) 1.3 is a redesign of the Web's most important security protocol. It was standardized in August 2018 after a four year-long, unprecedented design process involving many cryptographers and industry stakeholders. We use the rare opportunity to track deployment, uptake, and use of a new mission-critical security protocol from the early design phase until well over a year

Knowing domain names associated with traffic allows eavesdroppers to profile users without accessing packet payloads. Encrypting domain names transiting the network is, therefore, a key step to increase network confidentiality. Latest efforts include encrypting the TLS Server Name Indication (eSNI extension) and encrypting DNS traffic, with DNS over HTTPS (DoH) representing a prominent proposal. In

In this paper, we re-implement a recent work published in Usenix Security 2018: "Acquistional Rule Based Engine for Discovering Internet-of-Things Devices". The paper introduced an NLP-based engine for automatically identifying the type, vendor, and product of IoT devices given banner data as input. We report on our efforts to reproduce the original implementation of the engine, documenting ambiguities

Buffering architectures and policies for their efficient management are one of the core ingredients of network architecture. However, despite strong incentives to experiment with and deploy new policies, opportunities for changing or automatically choosing anything beyond a few parameters in a predefined set of behaviors still remain very limited. We introduce a novel buffer management framework based

To reflect the importance of network technologies, networking courses are now part of the core materials of Computer Science degrees. We report our experience in jointly developing an open-source ebook for the introductory course, and a series of open educational resources for both the introductory and advanced networking courses. These ensure students actively engage with the course materials, through

Due to the COVID-19 pandemic, the organizing committee of the 2020 edition of the Passive and Active Measurement (PAM) conference decided to organize it as a virtual event. Unfortunately, little is known about designing and organizing virtual academic conferences in the networking domain and their impacts on the participants' experience. In this editorial note, we first provide challenges and rationale

This editorial note aims to first inform the SIGCOMM community on the reviewing process in place currently at CCR, and second, share our plans to make CCR a more open and welcoming venue by making changes to the review process, adding more value to the SIGCOMM community.

Presentation of the April 2020 issue of CCR.

RIPE IPmap is a multi-engine geolocation platform operated by the RIPE NCC. One of its engines, single-radius, uses active geolocation to infer the geographic coordinates of target IP addresses. In this paper, we first introduce the methodology of IPmap's single-radius engine, then we evaluate its accuracy, coverage, and consistency, and compare its results with commercial geolocation databases. We

A commonly held belief is that traffic engineering and routing changes are infrequent. However, based on our measurements over a number of years of traffic between data centers in one of the largest cloud provider's networks, we found that it is common for flows to change paths at ten-second intervals or even faster. These frequent path and, consequently, latency variations can negatively impact the

Understanding web co-location is essential for various reasons. For instance, it can help one to assess the collateral damage that denial-of-service attacks or IP-based blocking can cause to the availability of co-located web sites. However, it has been more than a decade since the first study was conducted in 2007. The Internet infrastructure has changed drastically since then, necessitating a renewed

Artifact badging aims to rank the quality of submitted research artifacts and promote reproducibility. However, artifact badging may not indicate inherent design and evaluation limitations.

The strict low-latency requirements of applications such as virtual reality, online gaming, etc., can not be satisfied by the current Internet. This is due to the characteristics of classic TCP such as Reno and TCP Cubic which induce high queuing delays when used for capacity-seeking traffic, which in turn results in unpredictable latency. The Low Latency, Low Loss, Scalable throughput (L4S) architecture

Each year at ETH Zurich, around 100 students collectively build and operate their very own Internet infrastructure composed of hundreds of routers and dozens of Autonomous Systems (ASes). Their goal? Enabling Internet-wide connectivity. [email protected] find this class-wide project to be invaluable in teaching our students how the Internet infrastructure practically works. Among others, our students

On 9-11 December 2019, CAIDA hosted the 10th interdisciplinary Workshop on Internet Economics (WIE) at UC San Diego's Supercomputer Center. This workshop series provides a forum for researchers, Internet facilities and service providers, technologists, economists, theorists, policymakers, and other stakeholders to exchange views on current and emerging economic and policy debates. This year's meeting

Reproducibility: the extent to which consistent results are obtained when an experiment is repeated, is important as a means to validate experimental results, promote integrity of research, and accelerate follow up work. Commitment to artifact reviewing and badging seeks to promote reproducibility and rank the quality of submitted artifacts.

We dispute the authors' claim that SRPT is the crucial factor in achieving good FCT performance in datacenter networks.

We investigated Internet eXchange Points (IXPs) deployed across Latin America. We discovered that many Latin American states have been actively involved in the development of their IXPs. We further found a correlation between the success of a national IXP and the absence of local monopolistic ASes that concentrate the country's IPv4 address space. In particular, three IXPs have been able to gain local

Motivated by the rapid emergence of programmable switches, programmable network interface cards, and software packet processing, this paper asks: given a network task (e.g., virtualization or measurement) in a programmable network, should we implement it at the network's end hosts (the edge) or its switches (the core)? To answer this question, we analyze a range of common network tasks spanning virtualization

This January 2020 issue starts the fiftieth volume of Computer Communication Review. This marks an important milestone for our newsletter. This issue contains four technical papers and three editorial notes. In C-Share: Optical Circuits Sharing for Software-Defined Data-Centers, Shay Vargaftik and his colleagues tackle the challenge of designing data-center networks that combine optical circuit switches

Several "NewSpace" companies have launched the first of thousands of planned satellites for providing global broadband Internet service. The resulting low-Earth-orbit (LEO) constellations will not only bridge the digital divide by providing service to remote areas, but they also promise much lower latency than terrestrial fiber for long-distance routes. We show that unlocking this potential is non-trivial:

The Internet topology has significantly changed in the past years. Today, it is richly connected and flattened. Such a change has been driven mostly by the fast growth of peering infrastructures and the expansion of Content Delivery Networks as alternatives to reduce interconnection costs and improve traffic delivery performance. While the topology evolution is perceptible, it is unclear whether or

The Network Neutrality (NN) debate refers to the battle over the design of a regulatory framework for preserving the Internet as a public network and open innovation platform. Fueled by concerns that broadband access service providers might abuse network management to discriminate against third party providers (e.g., content or application providers), policymakers have struggled with designing rules

On July 24-25, 2018, MIT hosted an invitation-only workshop for network researchers from academia, industry, and the policy community engaged in the design and operation of test schemes to measure broadband access, in order to address the measurement challenges associated with highspeed (gigabit) broadband Internet access services. The focus of the workshop was on assessing the current state-of-the-art

Integrating optical circuit switches in data-centers is an on-going research challenge. In recent years, state-of-the-art solutions introduce hybrid packet/circuit architectures for different optical circuit switch technologies, control techniques, and traffic re-routing methods. These solutions are based on separated packet and circuit planes that cannot utilize an optical circuit with flows that

As SIGCOMM turns 50, it's interesting to ask how networking research has evolved over time. This is a set of personal observations about the "mindset" associated with Internet research.

While placing the paper "XORs in the Air" in the context of the theoretical and practical understanding of network coding, we present a view of the progress of the field of network coding, In particular, we examine the interplay of theory and practice in the field.

On 16-17 April 2018, CAIDA hosted its eleventh Workshop on Active Internet Measurements (AIMS-11). This workshop series provides a forum for stakeholders in Internet active measurement projects to communicate their interests and concerns, and explore cooperative approaches to maximizing the collective benefit of deployed infrastructure and gathered data. An overarching theme this year was scaling the