We explain the notion of software-defined networking (SDN), whose southbound interface may be implemented by the OpenFlow protocol. We describe the operation of OpenFlow and summarize the features of specification versions 1.0–1.4. We give an overview of existing SDN-based applications grouped by topic areas. Finally, we point out architectural design choices for SDN using OpenFlow and discuss their performance implications.

Wi-Fi is a popular wireless technology and is continuously extended to keep pace with requirements such as high throughput, real-time communication, dense networks, or resource and energy efficiency. The IEEE 802.11ax standard, also known as Wi-Fi 6, promises to provide data rates of up to almost 10 Gb/s, lower energy consumption, and higher reliability. Its capabilities go far beyond Wi-Fi 5 (802.11ac) and novel technical concepts have been introduced for this purpose. As such, the Wi-Fi 6 standard includes Multi-User Orthogonal Frequency Division Multiple Access (MU OFDMA), Multi-User Multiple-Input Multiple-Output (MU MIMO), new mechanisms for Spatial Reuse (SR), new mechanisms for power saving, higher-order modulation, and additional minor improvements. In this paper, we provide a survey of Wi-Fi 6. Initially, we provide a compact technological summary of Wi-Fi 5 and its predecessors. Then, we discuss the potential application domains of Wi-Fi 6, which are enabled through its novel features. Subsequently, we explain these features and review the related works in these areas. Finally, performance evaluation tools for Wi-Fi 6 and future roadmaps are discussed.

Time-Sensitive Networking (TSN) is an enhancement of Ethernet which provides various mechanisms for real-time communication. Time-triggered (TT) traffic represents periodic data streams with strict real-time requirements. Amongst others, TSN supports scheduled transmission of TT streams, i.e., the transmission of their frames by end stations is coordinated in such a way that none or very little queuing delay occurs in intermediate nodes. TSN supports multiple priority queues per egress port. The TAS uses so-called gates to explicitly allow and block these queues for transmission on a short periodic timescale. The TAS is utilized to protect scheduled traffic from other traffic to minimize its queuing delay. In this work, we consider scheduling in TSN which comprises the computation of periodic transmission instants at end stations and the periodic opening and closing of queue gates. In this paper, we first give a brief overview of TSN features and standards. We state the TSN scheduling problem and explain common extensions which also include optimization problems. We review scheduling and optimization methods that have been used in this context. Then, the contribution of currently available research work is surveyed. We extract and compile optimization objectives, solved problem instances, and evaluation results. Research domains are identified, and specific contributions are analyzed. Finally, we discuss potential research directions and open problems.

In this work, we present P4-IPsec, a concept for IPsec in software-defined networks (SDN) using P4 programmable data planes. The prototype implementation features ESP in tunnel mode and supports different cipher suites. P4-capable switches are programmed to serve as IPsec tunnel endpoints. We also provide a client agent to configure tunnel endpoints on Linux hosts so that site-to-site and host-to-site application scenarios can be supported which are the base for virtual private networks (VPNs). While traditional VPNs require complex key exchange protocols like IKE to set up and renew tunnel endpoints, P4-IPsec benefits from an SDN controller to accomplish these tasks. One goal of this experimental work is to investigate how well P4-IPsec can be implemented on existing P4 switches. We present a prototype for the BMv2 P4 software switch, evaluate its performance, and publish its source code on GitHub [1]. We explain why we could not provide a useful implementation with the NetFPGA SUME board. For the Edgecore Wedge 100BF-32X Tofino-based switch, we presented two prototype implementations to cope with a missing crypto unit. As another contribution of this paper, we provide technological background of P4 and IPsec and give a comprehensive review of security applications in P4, IPsec in SDN, and IPsec data plane implementations. According to our knowledge, P4-IPsec is the first implementation of IPsec for P4-based SDN.

The advent of quantum computers makes asymmetric cryptographic algorithms insecure and vulnerable. A promising solution to ensure the continued security attributes of confidentiality, integrity, and availability is the use of Post-Quantum Cryptography (PQC) algorithms. The adoption of quantum-safe algorithms takes place at a vastly different pace in different industries. In some industries, adoption processes are slow due to the required adaptation of regulations and standards. At the same time, long-lived products with non-PQC algorithms are more likely to become insecure during their lifetime. Vehicles are a prime example of long-lived products where the adoption of PQC proceeds slowly. When quantum computers are able to break relevant key lengths of asymmetric cryptography and, thus, render current vehicle systems insecure, vehicles that are developed and produced today will most likely remain in use. In this work, we provide a structured and comprehensive overview of the current migration state of PQC algorithms in the automotive area.We address use cases involving asymmetric cryptography in the automotive context that face the challenge of adapting PQC, such as internal vehicle networks, manufacturer-specific communication, and vehicle-to-everything communication. In addition, we review the standards concerning vehicle security and their relevance to PQC. Finally, we identify and discuss open research challenges regarding the adoption of PQC in the automotive domain and further steps towards quantum-safe vehicles.

Traditional IP multicast (IPMC) maintains state per IPMC group in core devices to distribute one-to-many traffic along tree-like structures through the network. This limits its scalability because whenever subscribers of IPMC groups change, forwarding state in the core network needs to be updated. Bit Index Explicit Replication (BIER) has been proposed by the IETF for efficient transport of IPMC traffic without the need of IPMC-group-dependent state in core devices. However, legacy devices do not offer the required features to implement BIER. P4 is a programming language which follows the software-defined networking (SDN) paradigm. It provides a programmable data plane by programming the packet processing pipeline of P4 devices. The contribution of this article is threefold. First, we provide a hardware-based prototype of BIER and BIER fast reroute (BIER-FRR) which leverages packet recirculation. Our target is the P4-programmable high-performance switching ASIC Tofino; the source code is publicly available. Second, we perform an experimental evaluation, with regard to failover time and throughput, which shows that up to 100 Gb/s throughput can be obtained and that failures affect BIER forwarding for less than 1 ms. However, throughput can decrease if switch-internal packet loss occurs due to missing recirculation capacity. As a remedy, we add more recirculation capacity by turning physical ports into loopback mode. To quantify the problem, we derive a prediction model for reduced throughput whose results are in good accordance with measured values. Third, we provide a provisioning rule for recirculation ports, that is applicable to general P4 programs, to avoid switch-internal packet loss due to packet recirculation. In a case study we show that BIER requires only a few such ports under realistic mixes of unicast and multicast traffic.