Software-defined wide area networking (SD-WAN) enables dynamic network policy control over a large distributed network via network updates . To be practical, network updates must be consistent (i.e., free of transient errors caused by updates to multiple switches), secure (i.e., only be executed when sent from valid controllers), and reliable (i.e., function despite the presence of faulty or malicious members in the control plane), while imposing only minimal overhead on controllers and switches. We present SERENE: a protocol for se cure and re liable ne twork updates for SD-WAN environments. In short: Consistency is provided through the combination of an update scheduler and a distributed transactional protocol. Security is preserved by authenticating network events and updates, the latter with an adaptive threshold cryptographic scheme. Reliability is provided by replicating the control plane and making it resilient to a dynamic adversary by using a distributed ledger as a controller failure detector. We ensure practicality by providing a mechanism for scalability through the definition of independent network domains and exploiting the parallelism of network updates both within and across domains. We formally define SERENE’s protocol and prove its safety with regards to event-linearizability. Extensive experiments show that SERENE imposes minimal switch burden and scales to large networks running multiple network applications all requiring concurrent network updates, imposing at worst a 16% overhead on short-lived flow completion and negligible overhead on anticipated normal workloads.

Traditionally, the only option for developers was to implement file systems (FSs) via drivers within the operating system kernel. However, there exists a growing number of file systems (FSs), notably distributed FSs for the cloud, whose interfaces are implemented solely in user space to (i) isolate FS logic, (ii) take advantage of user space libraries, and/or (iii) for rapid FS prototyping. Common interfaces for implementing FSs in user space exist, but they do not guarantee POSIX compliance in all cases, or suffer from considerable performance penalties due to high amounts of wait context switchs between kernel and user space processes. We propose DEFUSE: an interface for user space FSs that provides fast accesses while ensuring access correctness and requiring no modifications to applications. DEFUSE: achieves significant performance improvements over existing user space FS interfaces thanks to its novel design that drastically reduces the number of wait context switchs for FS accesses. Additionally, to ensure access correctness, DEFUSE: maintains POSIX compliance for FS accesses thanks to three novel concepts of bypassed file descriptor (FD) lookup , FD stashing , and user space paging . Our evaluation spanning a variety of workloads shows that by reducing the number of wait context switchs per workload from as many as 16,000 or 41,000 with filesystem in user space down to 9 on average, DEFUSE: increases performance 2× over existing interfaces for typical workloads and by as many as 10× in certain instances.

Software-defined wide area networking (SD-WAN) enables dynamic network policy control over a large distributed network via network updates. To be practical, network updates must be both consistent, i.e., free of transient errors caused by updates to multiple switches, and secure, i.e., free of errors caused by faulty or malicious members of the control plane. Besides, these properties must incur minimal overhead to controllers and switches.

In manySoftware-Defined Networking(SDN) deployments the control plane ends up beingactuallycentralized, yielding a single point of failure and attack. This paper models the interaction between the data plane and adistributedcontrol plane consisting of a set of failure-prone and potentially malicious (compromised) control devices, and implements a secure and robust controller platform that allows network administrators to integrate new network functionality as with a centralized approach. Concretely, the network administrator may program the data plane from the perspective of a centralized controller without worrying about distribution, asynchrony, failures, attacks, or coordination problems that any of these could cause. We introduce a formal SDN computation model for applying network policies and show that it isimpossibleto implementasynchronous non-blockingand strongly consistent SDN controller platforms in that model. We then present arobustSDNcontroller protocol (RoSCo) which implements (i) a protocol with provablylinearizable semanticsfor applying network policies that is resilient against faulty/malicious control devices as long as acorrect majorityexists, and (ii) a modification to the protocol that improves performance by relaxing the guarantees of linearizability to exploit commutativity among updates. Extensive experiments conducted with a functional prototype of RoSCo over a large networked infrastructure supporting Open vSwitch (OVS)-compatible Agilio CX™ SmartNIC hardware show that RoSCo induces bearable overhead. In fact, RoSCo achieves higher throughput in most cases investigated than the seminal Ravana platform which addresses only benign (crash) failures.