Operating System Design: The Xinu Approach, Linksys Version provides a comprehensive introduction to Operating System Design, using Xinu, a small, elegant operating system that serves as an example and a pattern for system design. The book focuses the discussion of operating systems on the microkernel operating system facilities used in embedded sy

Data center workloads increasingly rely on low-latency east-west traffic while also being able to dynamically move hosts for load balancing purposes. The expansion of Software-Defined Networking has made reconfiguring networks to accommodate diverse workloads possible and efficient. However, reestablishing communication after host migration can impose a relatively long delay. DCnet is a previously proposed architecture that assigns each host a virtual MAC address so it can move within the data center while retaining its original MAC and IP addresses. This paper evaluates the DCnet approach and compares its performance to traditional SDN reactive forwarding flow rule management. Latency and throughput are evaluated in an emulated environment utilizing Mininet, ONOS, and iPerf software. We show that DCnet matches reactive forwarding latency and steady-state throughput while improving on initial first-ping latency.

The networking research community and industry both use the Mininet network simulator to assess new network architectures and predict how new designs will perform. Mininet employs an emulation approach that uses concurrent processes running in a single computer instead of physical hardware. A user specifies a network consisting of network switches, routers, and host computers that have network interface connections and links connecting all the pieces. Mininet creates software artifacts to represent each of the network devices and allows application programs to send packets across the resulting network. Researchers often use the iPerf application to measure network performance. Many research papers report results from Mininet and iPerf and use the results to validate new designs for Software-Defined Networks (SDNs). However, there has been little investigation into the scenarios where these emulations can perform different than intended. The goal of this paper is to understand the edge cases of these emulation methods and understand the severity of these scenarios. This paper reports surprising anomalies in the results of Mininet and iPerf. We show that the choice of apparently valid configuration options can make the reported throughput completely invalid. Our initial discoveries focused on a complex simulation of a data center network. However, we were able to show that Mininet produces completely invalid results for a basic case: network traffic traveling across a single emulated link between two switches with no other network traffic. The paper makes recommendations for ways to configure Mininet to avoid some of the anomalies.

This latest textbook from bestselling author, Douglas E. Comer, is a class-tested book providing a comprehensive introduction to cloud computing. Focusing on concepts and principles, rather than commercial offerings by cloud providers and vendors, The Cloud Computing Book: The Future of Computing Explained gives readers a complete picture of the advantages and growth of cloud computing, cloud infrastructure, virtualization, automation and orchestration, and cloud-native software design. The book explains real and virtual data center facilities, including computation (e.g., servers, hypervisors, Virtual Machines, and containers), networks (e.g., leaf-spine architecture, VLANs, and VxLAN), and storage mechanisms (e.g., SAN, NAS, and object storage). Chapters on automation and orchestration cover the conceptual organization of systems that automate software deployment and scaling. Chapters on cloud-native software cover parallelism, microservices, MapReduce, controller-based designs, and serverless computing. Although it focuses on concepts and principles, the book uses popular technologies in examples, including Docker containers and Kubernetes. Final chapters explain security in a cloud environment and the use of models to help control the complexity involved in designing software for the cloud. The text is suitable for a one-semester course for software engineers who want to understand cloud, and for IT managers moving an organization’s computing to the cloud.

The SDN paradigm allows network management applications to configure and manage network devices directly. Researchers use simulators, emulation platforms, and experimental testbeds to evaluate ideas. Emulation and simulation platforms offer the advantages of more flexibility and larger scale; using a testbed produces more realistic and accurate results. Although they support SDN, the switches used in data centers pose an economic barrier for researchers. We propose DCLab that creates a low-cost reconfigurable SDN testbed using white-box switches. This letter explains the architecture of DCLab and reports experiments that demonstrate how it allows to overlay various logical topologies on a physical topology.

The articles in this special section focus on space and terrestrial integrated networks. Currently, many aerial platforms, satellite systems, and space and terrestrial integrated networks (STINs) have been developed, while some of them are still under construction. The basic idea of STIN is to simply connect heterogeneous devices, systems, and networks via the Internet, thus providing much more effective services than traditional infrastructures. Through effective acquisition, coordination, transmission, and aggregation of multi-dimensional information, the resource planning, task distribution, and action management of STIN can be realized. The goal is to provide all kinds of users a real-time and reliable communication infrastructure by conducting efficient collaboration. However, there are still many open issues that need to be solved. For example, signal distortion and fading in the network connections in the atmosphere often occur. Therefore, the design of STIN typically needs to take into account signal distortion and fading, multiple access interference, large latency, and so on. At present, the development of STIN has reached a crossroad. Radio resource management, transparent handover, network management, wireless communication, and other promising technologies (e.g., long-term evolution, software-defined networking [SDN], and device-to-device communication [D2D]) are critical research trends for such hybrid satellite-aerial-terrestrial networks.

Cloud computing and storage have become an integral part of online Internet services. Over the past decade, enterprises have steadily moved their applications and storage to the cloud paradigm. Server virtualisation enables cloud providers to utilise computational resources efficiently by employing virtual machines (VMs) and containers. As more enterprise applications are hosted by VMs in the cloud, a significant amount of network communication occurs among servers within a data centre, increasing so-called 'east-west communication'. In addition to scaling to accommodate more east-west traffic, future data centre networks must support efficient VM migration, which is used to optimise power consumption. This article proposes a new data centre network architecture called DCnet. DCnet changes addressing and routing at layers 2 and 3 completely to increase throughput and support live VM migration throughout an organisation, including across multiple data centres owned by an organisation that spans large geographic areas. DCnet retains compatibility with existing hardware by using the same frame format as standard protocols, specifically Ethernet and Internet protocol (IP). Furthermore, DCnet does not require any changes to applications and host operating systems or libraries. In addition to presenting the architecture, the article describes a test bed used to assess DCnet and reports experimental measurements.