Toward Open and Programmable Wireless Network Edge

Increasingly, the last hop connecting users to their enterprise and home networks is wireless. Wireless is becoming ubiquitous not only in homes and enterprises but in public venues such as coffee shops, hospitals, and airports. However, most of the publicly and privately available wireless networks are proprietary and closed in operation. Also, there is little effort from industries to move forward on a path to greater openness for the requirement of innovation. Therefore, we believe it is the domain of university researchers to enable innovation through openness. In this thesis work, we introduce and defines the importance of open framework in addressing the complexity of the wireless network. The Software Defined Network (SDN) framework has emerged as a popular solution for the data center network. However, the promise of the SDN framework is to make the network open, flexible and programmable. In order to deliver on the promise, SDN must work for all users and across all networks, both wired and wireless. Therefore, we proposed to create new modules and APIs to extend the standard SDN framework all the way to the end-devices (i.e., mobile devices, APs). Thus, we want to provide an extensible and programmable abstraction of the wireless network as part of the current SDN-based solution. In this thesis work, we design and develop a framework, weSDN (wireless extension of SDN), that extends the SDN control capability all the way to the end devices to support client-network interaction capabilities and new services. weSDN enables the control-plane of wireless networks to be extended to mobile devices and allows for top-level decisions to be made from an SDN controller with knowledge of the network as a whole, rather than device centric configurations. In addition, weSDN easily obtains user application information, as well as the ability to monitor and control application flows dynamically. Based on the weSDN framework, we demonstrate new services such as application-aware traffic management, WLAN virtualization, and security management

Enhancing Networks via Virtualized Network Functions

University of Minnesota Ph.D. dissertation. May 2019. Major: Computer Science. Advisor: Zhi-Li Zhang. 1 computer file (PDF); xii, 116 pages.In an era of ubiquitous connectivity, various new applications, network protocols, and online services (e.g., cloud services, distributed machine learning, cryptocurrency) have been constantly creating, underpinning many of our daily activities. Emerging demands for networks have led to growing traffic volume and complexity of modern networks, which heavily rely on a wide spectrum of specialized network functions (e.g., Firewall, Load Balancer) for performance, security, etc. Although (virtual) network functions (VNFs) are widely deployed in networks, they are instantiated in an uncoordinated manner failing to meet growing demands of evolving networks. In this dissertation, we argue that networks equipped with VNFs can be designed in a fashion similar to how computer software is today programmed. By following the blueprint of joint design over VNFs, networks can be made more effective and efficient. We begin by presenting Durga, a system fusing wide area network (WAN) virtualization on gateway with local area network (LAN) virtualization technology. It seamlessly aggregates multiple WAN links into a (virtual) big pipe for better utilizing WAN links and also provides fast fail-over thus minimizing application performance degradation under WAN link failures. Without the support from LAN virtualization technology, existing solutions fail to provide high reliability and performance required by today’s enterprise applications. We then study a newly standardized protocol, Multipath TCP (MPTCP), adopted in Durga, showing the challenge of associating MPTCP subflows in network for the purpose of boosting throughput and enhancing security. Instead of designing a customized solution in every VNF to conquer this common challenge (making VNFs aware of MPTCP), we implement an online service named SAMPO to be readily integrated into VNFs. Following the same principle, we make an attempt to take consensus as a service in software-defined networks. We illustrate new network failure scenarios that are not explicitly handled by existing consensus algorithms such as Raft, thereby severely affecting their correct or efficient operations. Finally, we re-consider VNFs deployed in a network from the perspective of network administrators. A global view of deployed VNFs brings new opportunities for performance optimization over the network, and thus we explore parallelism in service function chains composing a sequence of VNFs that are typically traversed in-order by data flows

Algorithms for advance bandwidth reservation in media production networks

Media production generally requires many geographically distributed actors (e.g., production houses, broadcasters, advertisers) to exchange huge amounts of raw video and audio data. Traditional distribution techniques, such as dedicated point-to-point optical links, are highly inefficient in terms of installation time and cost. To improve efficiency, shared media production networks that connect all involved actors over a large geographical area, are currently being deployed. The traffic in such networks is often predictable, as the timing and bandwidth requirements of data transfers are generally known hours or even days in advance. As such, the use of advance bandwidth reservation (AR) can greatly increase resource utilization and cost efficiency. In this paper, we propose an Integer Linear Programming formulation of the bandwidth scheduling problem, which takes into account the specific characteristics of media production networks, is presented. Two novel optimization algorithms based on this model are thoroughly evaluated and compared by means of in-depth simulation results

Accelerating Network Functions using Reconfigurable Hardware. Design and Validation of High Throughput and Low Latency Network Functions at the Access Edge

Providing Internet access to billions of people worldwide is one of the main technical challenges in the current decade. The Internet access edge connects each residential and mobile subscriber to this network and ensures a certain Quality of Service (QoS). However, the implementation of access edge functionality challenges Internet service providers: First, a good QoS must be provided to the subscribers, for example, high throughput and low latency. Second, the quick rollout of new technologies and functionality demands flexible configuration and programming possibilities of the network components; for example, the support of novel, use-case-specific network protocols. The functionality scope of an Internet access edge requires the use of programming concepts, such as Network Functions Virtualization (NFV). The drawback of NFV-based network functions is a significantly lowered resource efficiency due to the execution as software, commonly resulting in a lowered QoS compared to rigid hardware solutions. The usage of programmable hardware accelerators, named NFV offloading, helps to improve the QoS and flexibility of network function implementations. In this thesis, we design network functions on programmable hardware to improve the QoS and flexibility. First, we introduce the host bypassing concept for improved integration of hardware accelerators in computer systems, for example, in 5G radio access networks. This novel concept bypasses the system’s main memory and enables direct connectivity between the accelerator and network interface card. Our evaluations show an improved throughput and significantly lowered latency jitter for the presented approach. Second, we analyze different programmable hardware technologies for hardware-accelerated Internet subscriber handling, including three P4-programmable platforms and FPGAs. Our results demonstrate that all approaches have excellent performance and are suitable for Internet access creation. We present a fully-fledged User Plane Function (UPF) designed upon these concepts and test it in an end-to-end 5G standalone network as part of this contribution. Third, we analyze and demonstrate the usability of Active Queue Management (AQM) algorithms on programmable hardware as an expansion to the access edge. We show the feasibility of the CoDel AQM algorithm and discuss the challenges and constraints to be considered when limited hardware is used. The results show significant improvements in the QoS when the AQM algorithm is deployed on hardware. Last, we focus on network function benchmarking, which is crucial for understanding the behavior of implementations and their optimization, e.g., Internet access creation. For this, we introduce the load generation and measurement framework P4STA, benefiting from flexible software-based load generation and hardware-assisted measuring. Utilizing programmable network switches, we achieve a nanosecond time accuracy while generating test loads up to the available Ethernet link speed

High-performance software packet processing

In today’s Internet, it is highly desirable to have fast and scalable software packet processing solutions for network applications that run on commodity hardware. The advent of cloud computing drives the continued rapid growth of Internet traffic. Moreover, the development of emerging networking techniques, such as Network Function Virtualization, significantly shapes the need for implementing the network functions in software. Finally, with the advancement of modern platforms as well as software frameworks for packet processing, network applications have potential to process 100+ Gbps network traffic on a single commodity server. Representative frameworks include the Click modular router, the RouteBricks scalable routing architecture, and BUFFALO, the software-based Ethernet switch. Beneath this general-purpose routing and switching functionality lie a broad set of network applications, many of which are handled with custom methods to provide cost-effectiveness and flexibility. This thesis considers two long-standing networking applications, IP lookup and distributed denial-of-service (DDoS) mitigation, and proposes efficient software-based methods drawing from this new perspective. In this thesis, we first introduce several optimization techniques to accelerate network applications by taking advantage of modern CPU features. Then, we explore the IP lookup problem to find the longest matching prefix of an IP address in a set of prefixes. An ideal IP lookup algorithm should achieve small constant IP lookup time, and on-chip memory usage. However, no prior IP lookup algorithm achieves both requirements at the same time. We propose SAIL, a splitting approach to IP lookup, and a suite of algorithms for IP lookup based on SAIL framework. We conducted extensive experiments to evaluate our algorithms, and experimental results show that our SAIL algorithms are much faster than well-known IP lookup algorithms. Next, we switch our focus to DDoS, an attempt to disrupt the legitimate traffic of a victim by sending a flood of Internet traffic from different sources. Our solution is Gatekeeper, the first open-source and deployable DDoS mitigation system. We present a series of optimization techniques, including use of modern platforms, group prefetching, coroutines, and hashing, to accelerate Gatekeeper. Experimental results show that these optimization techniques significantly improve its performance over alternative baseline solutions.2022-01-30T00:00:00

Network Function Virtualization: state-of-the-art and research challenges

Network Function Virtualization (NFV) has drawn significant attention from both industry and academia as an important shift in telecommunication service provisioning. By decoupling Network Functions (NFs) from the physical devices on which they run, NFV has the potential to lead to significant reductions in Operating Expenses (OPEX) and Capital Expenses (CAPEX) and facilitate the deployment of new services with increased agility and faster time-to-value. The NFV paradigm is still in its infancy and there is a large spectrum of opportunities for the research community to develop new architectures, systems and applications, and to evaluate alternatives and trade-offs in developing technologies for its successful deployment. In this paper, after discussing NFV and its relationship with complementary fields of Software Defined Networking (SDN) and cloud computing, we survey the state-of-the-art in NFV, and identify promising research directions in this area. We also overview key NFV projects, standardization efforts, early implementations, use cases and commercial products.Peer ReviewedPostprint (author's final draft

An architectural approach for mitigating next-generation denial of service attacks

It is well known that distributed denial of service attacks are a major threat to the Internet today. Surveys of network operators repeatedly show that the Internet's stakeholders are concerned, and the reasons for this are clear: the frequency, magnitude, and complexity of attacks are growing, and show no signs of slowing down. With the emergence of the Internet of Things, fifth-generation mobile networks, and IPv6, the Internet may soon be exposed to a new generation of sophisticated and powerful DDoS attacks. But how did we get here? In one view, the potency of DDoS attacks is owed to a set of underlying architectural issues at the heart of the Internet. Guiding principles such as simplicity, openness, and autonomy have driven the Internet to be tremendously successful, but have the side effects of making it difficult to verify source addresses, classify unwanted packets, and forge cooperation between networks to stop traffic. These architectural issues make mitigating DDoS attacks a costly, uphill battle for victims, who have been left without an adequate defense. Such a circumstance requires a solution that is aware of, and addresses, the architectural issues at play. Fueled by over 20 years worth of lessons learned from the industry and academic literature, Gatekeeper is a mitigation system that neutralizes the issues that make DDoS attacks so powerful. It does so by enforcing a connection-oriented network layer and by leveraging a global distribution of upstream vantage points. Gatekeeper further distinguishes itself from previous solutions because it circumvents the necessity of mutual deployment between networks, allowing deployers to reap the full benefits alone and on day one. Gatekeeper is an open-source, production-quality DDoS mitigation system. It is modular, scalable, and built using the latest advances in packet processing techniques. It implements the operational features required by today's network administrators, including support for bonded network devices, VLAN tagging, and control plane tools, and has been chosen for deployment by multiple networks. However, an effective Gatekeeper deployment can only be achieved by writing and enforcing fine-grained and accurate network policies. While the basic function of such policies is to simply govern the sending ability of clients, Gatekeeper is capable of much more: multiple bandwidth limits, punishing flows for misbehavior, attack detection via machine learning, and the flexibility to support new protocols. Therefore, we provide a view into the richness and power of Gatekeeper policies in the form of a policy toolkit for network operators. Finally, we must look to the future, and prepare for a potential next generation of powerful and costly DDoS attacks to grace our infrastructure. In particular, link flooding attacks such as Crossfire use massive, distributed sets of bots with low-rate, legitimate-looking traffic to attack upstream links outside of the victim's control. A new generation of these attacks could soon be realized as IoT devices, 5G networks, and IPv6 simultaneously enter the network landscape. Gatekeeper is able to hinder the architectural advantages that fuel link flooding attacks, bounding their effectiveness