Global Networking

Network management is becoming increasingly automated, and automation depends on detailed, explicit representations of data about both the state of a network, and about an operator’s intent for its networks. In particular, we must explicitly represent the desired and actual topology of a network; almost all other network-management data either derives from its topology, constrains how to use a...

Abstract—Recent advances in programmable data planes, software-defined networking, and the adoption of IPv6, support novel, more complex load balancing strategies. We introduce the Multipath Classification Algorithm (MCA), a probing algorithm that extends traceroute to identify and classify load balancing in Internet routes. MCA extends existing formalism and techniques to consider that load...

Open optical networks present a variety of benefits such as single vendor independence and the opportunity to select best in class devices for each individual role. In this paper we review two degrees of open optical networks, namely ones with transponder-line system and line system-line system interoperability. In this context we discuss Google's experiences with respect to optical link...

We present NEL (Network Error Logging), Google’s planet scale, client-side, network reliability measurement system. NEL is implemented in Chrome and has been proposed as a new W3C standard, letting any web site operator collect reports of clients’ successful and failed requests to their sites. These reports are similar to web server logs, but include information about failed requests that never...

Since many years, the Q-budget table (normalized by the ITU-T G.977) has been widely used to characterize the transmission performance of subsea cables: this table detailed the margin allowance breakdown for any modulated wavelength. The fiber achievable transmission capacity was then deduced from the wavelength spacing and the system operating bandwidth. However, the emergence of coherent...

Private WANs are increasingly important to the operation of enterprises, telecoms, and cloud providers. For example, B4, Google’s private software-defined WAN, is larger and growing faster than our connectivity to the public Internet. In this paper, we present the five-year evolution of B4. We describe the techniques we employed to incrementally move from offering best-effort content-copy...

Modern networks have significantly outpaced the monitoring capabilities of SNMP and command-line scraping. Over the last three years we at Google have been working with members of the networking industry via the OpenConfig.net effort to redefine network monitoring. We have now deployed Streaming Telemetry in production to monitor devices from multiple vendors. We will talk about the experience...

We present the design of Espresso, Google’s SDN-based Internet peering edge routing infrastructure. This architecture grew out of a need to exponentially scale the Internet edge cost-effectively and to enable application-aware routing at Internet-peering scale. Espresso utilizes commodity switches and host-based routing/packet processing to implement a novel fine-grained traffic engineering...

Large flows like videos consume significant bandwidth. Some ISPs actively manage these high volume flows with techniques like policing, which enforces a flow rate by dropping excess traffic. While the existence of policing is well known, our contribution is an Internet-wide study quantifying its prevalence and impact on video quality metrics. We developed a heuristic to identify policing from...

Maintaining the highest levels of availability for content providers is challenging in the face of scale, network evolution, and complexity. Little, however, is known about the network failures large content providers are susceptible to, and what mechanisms they employ to ensure high availability. From a detailed analysis of over 100 high-impact failure events within Google’s network,...

By all accounts, today’s Internet is not moving data as well as it should. Most of the world’s cellular users experience delays of seconds to minutes; public Wi-Fi in airports and conference venues is often worse. Physics and climate researchers need to exchange petabytes of data with global collaborators but find their carefully engineered multi-Gbps infrastructure often delivers at only a few...

Maglev is Google’s network load balancer. It is a large distributed software system that runs on commodity Linux servers. Unlike traditional hardware network load balancers, it does not require a specialized physical rack deployment, and its capacity can be easily adjusted by adding or removing servers. Network routers distribute packets evenly to the Maglev machines via Equal Cost Multipath...

The convergence behavior of many distributed machine learning (ML) algorithms can be sensitive to the number of machines being used or to changes in the computing environment. As a result, scaling to a large number of machines can be challenging. In this paper, we describe a new scalable coordinate descent (SCD) algorithm for generalized linear models whose convergence behavior is always the...