Observing the Evolution of QUIC Implementations

The QUIC protocol combines features that were initially found inside the TCP, TLS and HTTP/2 protocols. The IETF is currently finalising a complete specification of this protocol. More than a dozen of independent implementations have been developed in parallel with these standardisation activities. We propose and implement a QUIC test suite that interacts with public QUIC servers to verify their conformance with key features of the IETF specification. Our measurements, gathered over a semester, provide a unique viewpoint on the evolution of a protocol and of its implementations. They highlight the arrival of new features and some regressions among the different implementations.Comment: 6 pages, 8 figure

TCPSnitch: Dissecting the Usage of the Socket API

Networked applications interact with the TCP/IP stack through the socket API. Over the years, various extensions have been added to this popular API. In this paper, we propose and implement the TCPSnitch software that tracks the interactions between Linux and Android applications and the TCP/IP stack. We collect a dataset containing the interactions produced by more than 120 different applications. Our analysis reveals that applications use a variety of API calls. On Android, many applications use various socket options even if the Java API does not expose them directly. TCPSnitch and the associated dataset are publicly available.Comment: See https://www.tcpsnitch.or

MCQUIC: Multicast and unicast in a single transport protocol

Multicast enables efficient one-to-many communications. Several applications benefit from its scalability properties, e.g., live-streaming and large-scale software updates. Historically, multicast applications have used specialized transport protocols. The flexibility of the recently standardized QUIC protocol opens the possibility of providing both unicast and multicast services to applications with a single transport protocol. We present MCQUIC, an extended version of the QUIC protocol that supports multicast communications. We show how QUIC features and built-in security can be leveraged for multicast transport. We present the design of MCQUIC and implement it in Cloudflare quiche. We assess its performance through benchmarks and in emulated networks under realistic scenarios. We also demonstrate MCQUIC in a campus network. By coupling QUIC with our multicast extension, applications can rely on multicast for efficiency with the possibility to fall back on unicast in case of incompatible network conditions.Comment: 13 page

Adaptive Address Family Selection for Latency-Sensitive Applications on Dual-stack Hosts

Latency is becoming a key factor of performance for Internet applications and has triggered a number of changes in its protocols. Our work revisits the impact on latency of address family selection in dual-stack hosts. Through RIPE Atlas measurements, we analyse the address families latency difference and establish two requirements based on our findings for a latency-focused selection mechanism. First, the address family should be chosen per destination. Second, the choice should be able to evolve over time dynamically. We propose and implement a solution formulated as an online learning problem balancing exploration and exploitation. We validate our solution in simulations based on RIPE Atlas measurements, implement and evaluate our prototype in four access networks using Chrome and popular web services. We demonstrate the ability of our solution to converge towards the lowest-latency address family and improve the latency of transport connections used by applications

Beyond socket options: making the Linux TCP stack truly extensible

The Transmission Control Protocol (TCP) is one of the most important protocols in today's Internet. Its specification and implementations have been refined for almost forty years. The Linux TCP stack is one of the most widely used TCP stacks given its utilisation on servers and Android smartphones and tablets. However, TCP and its implementations evolve very slowly. In this paper, we demonstrate how to leverage the eBPF virtual machine that is part of the recent versions of the Linux kernel to make the TCP stack easier to extend. We demonstrate a variety of use cases where the eBPF code is injected inside a running kernel to update or tune the TCP implementation. We first implement the TCP User Timeout Option. Then we propose a new option that enables a client to request a server to use a specific congestion control scheme. Our third extension is a TCP option that sets the initial congestion window. We then demonstrate how eBPF code can be used to tune the acknowledgment strategy.Comment: 9 pages, 8 figure