A Survey on Data Plane Programming with P4: Fundamentals, Advances, and Applied Research

With traditional networking, users can configure control plane protocols to match the specific network configuration, but without the ability to fundamentally change the underlying algorithms. With SDN, the users may provide their own control plane, that can control network devices through their data plane APIs. Programmable data planes allow users to define their own data plane algorithms for network devices including appropriate data plane APIs which may be leveraged by user-defined SDN control. Thus, programmable data planes and SDN offer great flexibility for network customization, be it for specialized, commercial appliances, e.g., in 5G or data center networks, or for rapid prototyping in industrial and academic research. Programming protocol-independent packet processors (P4) has emerged as the currently most widespread abstraction, programming language, and concept for data plane programming. It is developed and standardized by an open community and it is supported by various software and hardware platforms. In this paper, we survey the literature from 2015 to 2020 on data plane programming with P4. Our survey covers 497 references of which 367 are scientific publications. We organize our work into two parts. In the first part, we give an overview of data plane programming models, the programming language, architectures, compilers, targets, and data plane APIs. We also consider research efforts to advance P4 technology. In the second part, we analyze a large body of literature considering P4-based applied research. We categorize 241 research papers into different application domains, summarize their contributions, and extract prototypes, target platforms, and source code availability.Comment: Submitted to IEEE Communications Surveys and Tutorials (COMS) on 2021-01-2

Online Reprogrammable Multi Tenant Switches

Recent research shows many benefits for cloud workloads and network operations when putting software functionality onto switches. Sharing the physical resources of a programmable switch between multiple tenants and workloads enables the widespread deployment of on-switch software functionality. Currently, changing the program on a programmable switch incurs significant switch downtime, connectivity loss, and service interruption. We, therefore propose a modification to the common programmable switch architecture to enable hot-pluggability, the ability to insert, modify, and remove on-path software functionality without interrupting the network operation. With hot-pluggability, a programmable switch can be shared between applications of different on-switch lifetime and therefore also between different tenants. Such sharing requires performance and program isolation between different on-switch functions and tenants. Our proposal makes on-switch software functionality deployable within production networks and enables programmable switches to be offered as a service to multiple tenants within cloud and ISP networks

Type-Safe Data Plane Programming

Since the mid-1990s, there have been efforts to enable more flexible processing of network packets by making packet processing programmable. With the advent of software-defined networking (SDN), this idea has now become a reality. Early approaches initially focused on control plane programming, with the goal of implementing centralized network policies at a high level of abstraction without having to use low-level, device-specific configuration mechanisms. For this purpose, various network programming languages have been developed, which provide correctness guarantees and make the formal verification of network policies possible. More recently, it is also possible to program the network data plane. Being able to define the structure of network packet headers freely, opens up a whole new range of applications, from implementing new network protocols up to moving application logic directly into the network. Until today, the P4 language has become the de facto standard for programming data planes. While P4 provides declarative abstractions for programming data planes, P4 lacks basic safety guarantees to help avoid errors and implement correct applications for the data plane. Modern programming languages use static type systems to provide languages with basic safety guarantees that completely eliminate the occurrence of entire categories of errors. Surprisingly, however, the use of type systems in the field of network programming has hardly been investigated. This dissertation investigates what appropriate type systems must look like in order to provide data plane programming languages—in particular, P4—with static correctness guarantees. As a first step, we present SafeP4, a domain-specific language for programmable data planes that is equipped with a static type system that guarantees that all headers that are read or written are valid, which is a common cause of errors. We then present Π4, whose type system is based on dependent types and is thus able to bridge the gap in terms of expressiveness between SafeP4 and full-fledged verification tools. At the same time, Π4 enables modular verification of programs. Our evaluation using open source programs confirms that accessing invalid packet headers is a common source of errors in practice and that the SafeP4’s type system is capable of identifying buggy programs. Using case studies, we show that Π4’s type system is capable of expressing and verifying a variety of real-world correctness properties