Magnos Martinello

SlickFlow: Resilient source routing in Data Center Networks unlocked by OpenFlow

Recent proposals on Data Center Networks (DCN) are based on centralized control and a logical network fabric following a well-controlled baseline topology. The architectural split of control and data planes and the new control plane abstractions have been touted as Software-Defined Networking (SDN), where the OpenFlow protocol is one common choice for the standardized programmatic interface to data plane devices. In this context, source routing has been proposed as a way to provide scalability, forwarding flexibility and simplicity in the data plane. One major caveat of source routing is network failure events, which require informing the source node and can take at least on the order of one RTT to the controller. This paper presents SlickFlow, a resilient source routing approach implemented with OpenFlow that allows fast failure recovery by combining source routing with alternative path information carried in the packet header. A primary and alternative paths are compactly encoded as a sequence of segments written in packet header fields. Under the presence of failures along a primary path, packets can be rerouted to alternative paths by the switches themselves without involving the controller. We evaluate SlickFlow on a prototype implementation based on Open vSwitch and demonstrate its effectiveness in a Mininet emulated scenario for fat-tree, BCube, and DCell topologies.

Keyflow: a prototype for evolving SDN toward core network fabrics

The large bulk of packets/flows in future core networks will require a highly efficient header processing in the switching elements. Simplifying lookup in core network switching elements is capital to transport data at high rates and with low latency. Flexible network hardware combined with agile network control is also an essential property for future software-defined networking. We argue that only further decoupling between the control and data planes will unlock the flexibility and agility in SDN for the design of new network solutions for core networks. This article proposes a new approach named KeyFlow to build a flexible network-fabricbased model. It replaces the table lookup in the forwarding engine by elementary operations relying on a residue number system. This provides us tools to design a stateless core network by still using OpenFlow centralized control. A proof of concept prototype is validated using the Mininet emulation environment and OpenFlow 1.0. The results indicate RTT reduction above 50 percent, especially for networks with densely populated flow tables. KeyFlow achieves above 30 percent reduction in keeping active flow state in the network.

A Survey on SDN Programming Languages: Toward a Taxonomy

Network devices have always been considered as configurable black boxes until the emergence of software-defined networking (SDN). SDN enables the networks to be programmed according to the user requirements; furthermore, it allows the network to be easily modified to suit transient demands. However, how do we program the network? SDN-compliant switches offer a low-level interface that makes programming error-prone. The controllers provide application programming interfaces, but still low-level, limited, and inflexible. High-level languages have the potential to be a better alternative to program the network. There exist several SDN programming languages implementing different sets of functionalities, and focusing on solving various issues. In face of all this diversity, no published paper outlines a pragmatic view allowing to compare the SDN languages. This paper presents a systematic survey of up-to-date OpenFlow-based SDN programming languages. Our approach relies on a taxonomy comprising all prominent features found in those languages. A detailed review of the existing works is carried out investigating the foundational parts of the languages with their contributions. Examples are discussed to illustrate the fundamental abstractions. Last, all gathered information is summarized, discussing the main ongoing research efforts and challenges. Future abstractions and features to be incorporated into the next generations of SDN programming languages are also considered.

Data Center Fault-Tolerant Routing and Forwarding: An Approach Based on Encoded Paths

Traditional layer 2 and layer 3 network designs face some limitations on data center networks such as lack of scalability, difficult management and inflexible communication. We observe that data center networks are often managed as a single logical network fabric with a well-controlled baseline topology and growth model. This paper describes a data center networking approach based on encoded paths carried in the packet header. We present an Open Flow-based test bed implementation of a data center architecture governed by a logically centralized Network Manager, which is responsible to transparently provide the networking and support functions to operate the data center network. We evaluate the proposal in terms of fail recovery time, state requirements, and load balancing capabilities. The results of the experiments show that our proposal improves the fail recovery time, while preserving scalability requirements.

SDCCN: A Novel Software Defined Content-Centric Networking Approach

Content Centric Networking (CCN) represents an important change in the current operation of the Internet, prioritizing content over the communication between end nodes. Routers play an essential role in CCN, since they receive the requests for a given content and provide content caching for the most popular ones. They have their own forwarding strategies and caching policies for the most popular contents. Despite the number of works on this field, experimental evaluation of different forwarding algorithms and caching policies yet demands a huge effort in routers programming. In this paper we propose SDCCN, a SDN approach to CCN that provides programmable forwarding strategy and caching policies. SDCCN allows fast prototyping and experimentation in CCN. Proofs of concept were performed to demonstrate the programmability of the cache replacement algorithms and the Strategy Layer. Experimental results, obtained through implementation in the Mininet environment, are presented and evaluated.

FlexForward: Enabling an SDN manageable forwarding engine in Open vSwitch

This paper presents FlexForward, an approach for dynamically manage SDN data plane forwarding mechanisms. This feature leverages SDN flexibility in two aspects: (i) it provides a new management method, in which topological infrastructure requirements are satisfied by the most appropriate forwarding mechanism, residing in each managed network element; (ii) further decoupling between control and data planes in SDN by offering tableless forwarding support. As proof of concept, an implementation with different forwarding methods is carried out in Open vSwitch. Results show that FlexForward is able to achieve seamless switchover between forwarding methods. It also allows efficient tableless forwarding implementations, improving by up to 31% in latency, and 90% in throughput, when compared to regular OpenFlow.

Resilient Strategies to SDN: An Approach Focused on Actively Replicated Controllers

Software Defined Networking (SDN) are based on the separation of control and data planes. The SDN controller, although logically centralized, should be effectively distributed for high availability. Since the specification of OpenFlow 1.2, there are new features that allow the switches to communicate with multiple controllers that can play different roles -- master, slave, and equal. However, these roles alone are not sufficient to guarantee a resilient control plane and the actual implementation remains an open challenge for SDN designers. In this paper, we explore the OpenFlow roles for the design of resilient SDN architectures relying on multi-controllers. As a proof of concept, a strategy of active replication was implemented in the Ryu controller, using the OpenReplica service to ensure consistent state among the distributed controllers. The prototype was tested with commodity RouterBoards/MikroTik switches and evaluated for latency in failure recovery and switch migration for different workloads. We observe a set of trade-offs in real experiments with varyin workloads at both the data and control plane.

PathCrawler: Automatic harvesting web infra-structure

As network topologies have grown in size and complexity, it is becoming a daunting task for network administrators to keep track the capacity dimensioning of newly installed web-servers within a single or multiple providers. In fact, monitor capacity dimensioning is not a trivial activity since network state changes rather frequently, in particular, in academic environments. In this paper, we describe estimation algorithms and the software architecture of an efficient network management suite to automatically mine path capacity and minimum delays from a venture point to a set of observed web servers. The principle of the suite is based on packet dispersion techniques and repetitive non-intrusive measurements. We provide analytical insights, simulation results and some real case studies where we argument about the correctness, accuracy and usefulness of the suite in the context of management and operation of complex IP based networks.

From software defined network to network defined for software

Nowadays, Big Data applications exchange huge amounts of data, highly demanding network guarantees for bandwidth and low latency. However, network equipments did not provide a standard interface to control dynamically the resources. Software-Defined Network (SDN) has emerged to support network programmability, but it provides a programming model devoted to network operators. This paper presents the Network Overlay Framework (NoF), which enables networks to be defined based on application requirements. NoF provides a programming language which allows the application specialists to program the network. A compiler translates NoF programs into instructions according to the underlying network technology. To prove the effectiveness of NoF, programs were implemented to express bandwidth guarantees on Hadoop traffic and also to route Hadoop flows through overlay networks.

LiCoB: Lightweight Collaborative Browsing

Collaborative navigation systems provide a useful way for virtual groups to share information through the web. However, the common set of features of these tools is not enough to offer a more face-to-face-like browsing experience. To fill this gap, this paper presents a novel collaborative navigation approach, which aims at integrating important features of a lightweight distributed architecture, awareness, session state sharing and annotations. In order to demonstrate the feasibility of our approach, LiCoB prototype was developed and then, evaluated considering performance issues.