Software Defined Networking Control Plane Research Articles

An open line architecture to enable white-box optical ecosystem

Abstract The white-box optical ecosystem is considered as the future trend in transport networks, which includes the openness in both software and hardware. The openness in hardware decomposes the equipment into multiple independent components to reduce costs. And the openness in software including general YANG models make all components controllable, which enables fast innovation in the control plane of software-defined networking (SDN). In this paper, an open line architecture (OLA) is proposed to implement the openness and disaggregation to enable white-box optical ecosystem. OLA defines a transport application interface (TAPI) to provide a flexible control of the open line system. To build the physical network, OLA uses the optical equipment developed by different manufacturers that follows specific YANG specifications. And in the control plane, OLA develops a series of drivers and applications to control the calculation, creation, and deletion of optical connectivity service. Finally, the paper shows OLA in use as part of a testbed, which demonstrates the feasibility of building networks consisting of both open and disaggregated hardware.

P4Consist: Toward Consistent P4 SDNs

The prevailing wisdom is that a software-defined network (SDN) operates under the premise that the logically centralized control plane has an accurate representation of the actual data plane state. Unfortunately, bugs, misconfigurations, faults or attacks can introduce inconsistencies between the network control and the data plane that can undermine the correct operation at runtime. Through our experiments, we realize that P4 SDNs are no exception, and are prone to similar problems. With the aim to verify the control-data plane inconsistency, we present the design and implementation of P4Consist, a system to detect the inconsistency between control and data plane in P4 SDNs. P4Consist generates active probe-based traffic continuously or periodically as an input to the P4 SDNs to check whether the actual behavior on the data plane corresponds to the expected control plane behavior. In P4Consist, the control plane and the data plane generate independent reports which are later, compared to verify the control-data plane consistency. The previous works in the field of monitoring and verification mostly aim to test the P4 programs through static analysis and thus, are insufficient to verify the network consistency at runtime. Experiments with our prototype implementation of P4Consist are promising and show that P4Consist can verify the control-data plane consistency in the complex datacenter 4-ary fat-tree (20 switches) and multipath grid (4, 9 and 16 switches) topologies with 60k rules per switch within a minimum time of 4 minutes. At the same time, P4Consist scales to multiple source-destination pairs to detect control-data plane inconsistency.

SDN enabled flexible optical data center network with dynamic bandwidth allocation based on photonic integrated wavelength selective switch.

Optical switching techniques featuring the fast and large capacity have the potential to enable low latency and high throughput optical data center networks (DCN) to afford the rapid increasing of traffic-boosted applications. Flexibility of the DCN is of key importance to provide adaptive and dynamic bandwidth to handle the variable traffic patterns generated by the heterogeneous applications while optimizing the network resources. Aiming at providing the flexible bandwidth for optical DCNs, we propose and experimentally investigate a software-defined networking (SDN) enabled reconfigurable optical DCN architecture based on novel optical top of rack (OToR) switch exploiting photonic-integrated wavelength selective switch. Experimental results show that the optical bandwidth per link can be automatically reallocated under the management of the deployed SDN control plane according to the variable traffic patterns. With respect to the network with inflexible interconnections, the average packet loss of the reconfigurable DCN decreases 1 order of magnitude and the server-to-server latency performance improves of 42.2%. Scalability investigation illustrates limited (11.7%) performance degradation as the reconfigurable network scale from 2560 to 40960 servers. Both the numerical and experimental assessments validate the proposed DCN with reconfigurable bandwidth feature and lower latency variations with respect to the inflexible DCNs.

Musings on change: driver for SDN

In this talk, we examine change and the rate of change from antiquity to the present, and we extrapolate to the future. We draw on the measures of social development due to historian Ian Morris. This shows that we are in an age of exponentially-increasing rate of change that will only increase unpredictably in the future. This necessitates a flexible architecture for the Internet to handle the future. We motivate the needs by the FarmerZone project, a futuristic application of AI to precision agriculture in India. Software-defined networks (SDN) is a promising alternative to the inflexible hardware routers of today's Internet. We discuss some of the challenges of SDN. One is rollout of SDN routers without disrupting the Internet. Another is scalability of the control plane of SDN. As SDN tends to be multi-vendor, ensuring security is a particularly difficult challenge. Rapid mobility with wireless networks is another issue.

Exploring the role of paths for dynamic switch assignment in software-defined networks

The distributed control plane of Software-Defined Networks improves the scalability of the control plane and enables to dynamically assign switches to controllers. However, existing works calculate the assignment mainly based on the number of flow path setup requests generated from the switches and neglect the different resource demand of the requests on the controllers. To address this problem, we analyze the controller resource demands of the requests of different paths and formulate a flow path-aware switch assignment problem to minimize the controller resource demand. To efficiently solve the problem, we propose a heuristic algorithm which is inspired by the rearrangement inequality theory to accommodate to the frequent flow fluctuation. Simulation results show that our solution can save the controller resources significantly compared with the existing solutions.

Queueing Theoretic Approach for Performance-Aware Modeling of Sustainable SDN Control Planes

Software Defined Networking (SDN) provides flexibility and programmability for network management by using a layered structure composed of data plane, control plane, and application plane. A key enabling technique for the sustainability of SDN-based network infrastructure is the modeling of power consumed by SDN control planes. However, power modeling of control planes is not extensively investigated yet, and no generic methods have been developed for performance and power comparison of sustainable SDN control planes. In this paper, we propose analytical performance and power models for different network controllers by using queuing theory, and design a generic framework for performance and power evaluation of different sustainable SDN control planes. Extensive simulation results show that the proposed solution can precisely model the power and performance of the concerned SDN control planes such that different control planes can be benchmarked under a general framework, which enables the identification of suitable control planes for various SDN network applications.

Secure Collecting, Optimizing, and Deploying of Firewall Rules in Software-Defined Networks

Firewalls are a fundamental element of network security systems with the ability to block network data traffic flows according to pre-defined rules. Software-defined networking (SDN) technology, which can provide flexibility, elasticity, and programmability for network management, has been applied to network security systems. We propose a software-defined firewall cyber-security system, which securely gathers the firewall rules of the host/network-based firewalls through the SDN control plane, converts the collected firewall rules in the form of SDN flow rules, and deploys them on OpenFlow (OF)-enabled switches. Furthermore, we formulate an optimization problem to find appropriate OF-enabled switches to which the SDN flow rules are to be sent. The proposed firewall system makes the traffic flows that are destined to be dropped by a firewall be dropped in advance at the OF-enabled switch with the corresponding SDN flow rules. The SDN-based testbed experiments demonstrate that the proposed firewall system reduces the aggregate network traffic volume and the resource utilization of end-hosts in the network.

Achieving Near-Optimal Traffic Engineering Using a Distributed Algorithm in Hybrid SDN

To empower advanced traffic engineering (TE) mechanism, while considering the infeasibility of one-step migration to software-defined networking (SDN), SDN nodes are incrementally deployed into legacy network, which gives rise to hybrid SDN. In hybrid SDN, redirecting flow of every source-destination pair through at least one SDN node, can enhance TE performance and obtain flow manageability, while on the other hand leading to increasing demands of TCAM resources in SDN nodes. In this paper, we make minimization of maximum link utilization as the TE objective, and comply with SDN waypoint enforcement and TCAM resource limitation. We first formulate the TE problem as an integer linear programming (ILP) model and solve it in a centralized manner, where SDN waypoint selection and splitting fractions for each flow are jointly determined. Then, based on a fact that the logically centralized control plane in hybrid SDN is composed of multiple physically decentralized controllers, each of which manages part of SDN nodes, as well as considering a real situation that a centralized solution is infeasible or too fragile for large-scale network, we develop a distributed algorithm deriving from Lagrangian decomposition theory to effectively solve the TE problem. The simulation results indicate that, when 30% of the SDN nodes are deployed, the proposed traffic engineering-aware distributed routing (TEDR) algorithm obtains maximum link utilization comparable to that of full SDN, and has a limited influence on the routing efficiency.

SDN-Enabled Network Coding-Based Secure Data Dissemination in VANET Environment

Security and reliability in data transmission are considered as the challenging concerns in VANET. Software-defined networking (SDN) and network coding (NC) are the two key apprehensions in networking that have caught much attention from both industry and academia in recent years. Decoupling of control plane and data plane in SDN enables the centralized control of the network, providing flexibility to a great extent. On the other hand, NC has shown immense potential for improving robustness and security when deployed on VANET. This article advocates for the design of an architecture which exercises the SDN concept by incorporating NC with multigeneration-mixing (MGM) functionalities to increase reliability as well as security of data transmission in vehicular networks. We design an MGM-based NC protocol for encoding and decoding of data. Moreover, a centralized SDN controller takes charge of authentication of vehicles. Finally, we build a simulation model based on realistic traffic and communication characteristics. The simulation results show that the proposed protocol leveraged by the SDN framework outperforms the conventional NC-based protocol in case of security and reliability. Moreover, the simulation model is exhibited and point-by-point execution assessment is given to demonstrate the scalability and prevalence of the proposed strategy.

Generic Validation Criteria and Methodologies for SDN Applications

Programmable control plane in software-defined networking (SDN), plays an essential role in the SDN architecture. The network function provided by the specialized hardware in a legacy network can be created in the form of software-based “SDN application” running on the controllers to manipulate entire network configurations. Therefore, the risk of having software bugs and errors in the SDN applications may threaten the normal operations of SDN networks. This paper presents systematic validation criteria and test cases based on the proposed novel methodologies for SDN application testing. The test framework can perform testbed build-up, generate desired packet sequences, and analyze results automatically. According to the results of a generic test suite, several issues are unveiled in the application under test (AUT). Some AUTs, which need to check all the incoming packets from OpenFlow switches, fail to meet the test criteria of burst packet-in and flow self-recycling. For most of the applications based on the Ryu controller, the evaluation results reveal that some are unable to recycle flow entries after they are unloaded. It is recommended that all flows populated by SDN applications must have timeout value specified to prevent unnecessary entries kept in the flow table.

A survey of control consistency in Software-Defined Networking

Software-Defined Networking (SDN) offers a flexible and programmable model to manage and schedule network resources. With the separation of control plane and data plane in SDN, the centralized controller frequently updates the flow tables in data plane to control network, and the data plane also communicates its requests with the control plane for forwarding actions. Due to the asynchronous control nature of SDN, a SDN network may suffer from inconsistency issues caused by concurrency violations, which may lead to network misbehaviors, such as communication interruption, policy violation, and performance degradation. To make SDN correct and stable, consistency is an essential feature that SDN should possess. In this paper, we make a survey about the control consistency in SDN from three aspects: (1) a consistent network view and control decisions made by the control plane, (2) consistency and efficiency during data plane update, (3) maintaining consistent flow tables in the data plane. We summarize the fundamental causes of consistency issues, the potential inconsistency problems and the state-of-art solutions, and then discuss the challenges to guarantee the consistency for SDN.

An Analysis of Hierarchical Software-Defined Network Control Plane: A Reliability Approach

Present-day computer systems have drastically transformed from the ones in days of basic file sharing, peripheral sharing or the hosting of companywide applications on a server to much more sophisticated, small and faster systems. These systems have further expanded to include cloud-based networks, virtualized desktops, servers, etc. The capabilities of evolving heterogeneous computer systems require advanced control plane. Software-defined networking (SDN) proposes to control the network from a centralized controller instead of a distributed configuration. SDN makes it easier for network operators to evolve network capabilities. Even though SDN proposes a logically centralized system, the controllers may not represent a single, centralized device, instead the control plane may consist of logically centralized but physically distributed controllers wherein each controller manages different administrative domains of the network or different parts of the flow space. There are mainly two types of control plane architecture: flat control plane and hierarchical control plane. In this paper, we have analyzed the reliability and availability of the hierarchical SDN control plane. We take into consideration work-load capacities of the controllers, link failures, node failures and controller-end failures to determine the reliability of the system.

A Survey on Controller Placement in SDN

In recent years, Software Defined Networking (SDN) has emerged as a pivotal element not only in data-centers and wide-area networks, but also in next generation networking architectures such as Vehicular ad hoc network and 5G. SDN is characterized by decoupled data and control planes, and logically centralized control plane. The centralized control plane in SDN offers several opportunities as well as challenges. A key design choice of the SDN control plane is placement of the controller(s), which impacts a wide range of network issues ranging from latency to resiliency, from energy efficiency to load balancing, and so on. In this paper, we present a comprehensive survey on the controller placement problem (CPP) in SDN. We introduce the CPP in SDN and highlight its significance. We present the classical CPP formulation along with its supporting system model. We also discuss a wide range of the CPP modeling choices and associated metrics. We classify the CPP literature based on the objectives and methodologies. Apart from the primary use-cases of the CPP in data-center networks and wide area networks, we also examine the recent application of the CPP in several new domains such as mobile/cellular networks, 5G, named data networks, wireless mesh networks and VANETs. We conclude our survey with discussion on open issues and future scope of this topic.

The controller placement problem for robust SDNs against malicious node attacks considering the control plane with and without split-brain

In software-defined networking (SDN), the control plane is separated from the data plane. For scalability and robustness reasons, the logically centralized control plane is implemented by physically distributing different controllers throughout the network. The determination of the number and location of the SDN controllers is known as the controller placement problem (CPP). For given maximum switch-controller (SC) and controller-controller (CC) delays in the regular (failure-free) state, we aim to find a CPP solution that maximizes the control plane robustness against a given number of malicious node attacks. We describe an ILP-based method aiming to enumerate all CPP solutions that guarantee the existence of a data plane path from every switch to any controller if all other controller nodes are shut down (worst-case scenario). Then, for different malicious node attacks, based on node centrality metrics and corresponding to different attacker’s strategies, we evaluate the previous solutions to determine the ones that maximize the network robustness, considering the SDN control plane operating with or without split-brain. In the computational results, we compare the robustness and the average SC and CC delays of the best CPP solutions. Since a control plane with split-brain requires more controllers, the average SC and CC delays in the regular state of its CPP solutions are significantly better, on average. Concerning robustness, split-brain does not always provide the best robust CPP solutions due to its feature of requiring a minimum number of connected controllers (which must be over half of the total number of them) to be operational.

Falcon: Differential fault localization for SDN control plane

The control plane of Software-Defined Networking (SDN) is the key component for overseeing and managing networks. As a software entity, the control plane is inevitable to involve design or logic flaws in its policy enforcement and network control, which can cause it to behave incorrectly and induce network anomalies. Existing approaches mainly focus on policy verification or fault troubleshooting, which have little fault localization capabilities for locating these flaws in production environments. In this paper, we present Falcon, the first Fault localization tool for the SDN control plane. We design a novel causal inference mechanism based on differential checking, which symmetrically compares two system behaviors with similar processes and identifies the causality in related code execution paths with concrete contexts to explain why a fault happened in the SDN network. Our main contributions include (1) a lightweight rule-based hybrid tracing mechanism for recording system behaviors of the SDN control plane, (2) a context-aware modeling mechanism for modeling these behaviors, and (3) a differential checking mechanism for diagnosing controller faults according to formulated symptoms. Our evaluation shows that Falcon is capable of diagnosing faults in the SDN control plane with low overhead on performance.

HiAuth: Hidden Authentication for Protecting Software Defined Networks

Software defined networking (SDN) enables network function programmability for ease of configuration and maintenance, and also allows network administrators to change traffic rules on the fly. However, denial of service (DoS) attacks pose security challenges on the centralized control plane of SDN. Although the transport layer security (TLS) can help secure the control plane, it is computationally intensive, complex to configure, and not mandatory in OpenFlow protocol. In this paper, we present a lightweight authentication solution, called hidden authentication (HiAuth), to protect the SDN controller by hiding the identities of the forwarding devices into the control packets via efficient bitwise operations. HiAuth is the first to incorporate information hiding techniques into OpenFlow to provide security against DoS attacks. HiAuth exploits the IP identification field of IPv4 and the transaction identification field of OpenFlow in two authentication schemes. The experimental results show that HiAuth can effectively mitigate intruder DoS attacks and provide high undetectability to attackers.

Deep Learning SDN Intrusion Detection Scheme Based on TW-Pooling

The numerical control separation in the Software-Defined Network (SDN) allows the control plane to have the absolute management rights of the network. As a new management plane of the SDN, once it is attacked, it will cause the entire network to face flaws. For this reason, this paper proposes a SDN control plane attack detection scheme based on deep learning, which can detect and respond to attacks on the SDN control plane in time. In this scenario, we propose a new pooling scheme that uses the TF-IDF idea to weight the characteristics of network traffic. Ultimately, our method achieved an accuracy of 99.8% in the SDN network’s traffic data set including 24 attack types.

MmWave Backhaul Testbed Configurability Using Software-Defined Networking

Future mobile data traffic predictions expect a significant increase in user data traffic, requiring new forms of mobile network infrastructures. Fifth generation (5G) communication standards propose the densification of small cell access base stations (BSs) in order to provide multigigabit and low latency connectivity. This densification requires a high capacity backhaul network. Using optical links to connect all the small cells is economically not feasible for large scale radio access networks where multiple BSs are deployed. A wireless backhaul formed by a mesh of millimeter-wave (mmWave) links is an attractive mobile backhaul solution, as flexible wireless (multihop) paths can be formed to interconnect all the access BSs. Moreover, a wireless backhaul allows the dynamic reconfiguration of the backhaul topology to match varying traffic demands or adaptively power on/off small cells for green backhaul operation. However, conducting and precisely controlling reconfiguration experiments over real mmWave multihop networks is a challenging task. In this paper, we develop a Software-Defined Networking (SDN) based approach to enable such a dynamic backhaul reconfiguration and use real-world mmWave equipment to setup a SDN-enabled mmWave testbed to conduct various reconfiguration experiments. In our approach, the SDN control plane is not only responsible for configuring the forwarding plane but also for the link configuration, antenna alignment, and adaptive mesh node power on/off operations. We implement the SDN-based reconfiguration operations in a testbed with four nodes, each equipped with multiple mmWave interfaces that can be mechanically steered to connect to different neighbors. We evaluate the impact of various reconfiguration operations on existing user traffic using a set of extensive testbed measurements. Moreover, we measure the impact of the channel assignment on existing traffic, showing that a setup with an optimal channel assignment between the mesh links can result in a 44% throughput increase, when compared to a suboptimal configuration.

Dynamic SDN Controller Load Balancing

The software defined networking (SDN) paradigm separates the control plane from the data plane, where an SDN controller receives requests from its connected switches and manages the operation of the switches under its control. Reassignments between switches and their controllers are performed dynamically, in order to balance the load over SDN controllers. In order to perform load balancing, most dynamic assignment solutions use a central element to gather information requests for reassignment of switches. Increasing the number of controllers causes a scalability problem, when one super controller is used for all controllers and gathers information from all switches. In a large network, the distances between the controllers is sometimes a constraint for assigning them switches. In this paper, a new approach is presented to solve the well-known load balancing problem in the SDN control plane. This approach implies less load on the central element and meeting the maximum distance constraint allowed between controllers. An architecture with two levels of load balancing is defined. At the top level, the main component called Super Controller, arranges the controllers in clusters, so that there is a balance between the loads of the clusters. At the bottom level, in each cluster there is a dedicated controller called Master Controller, which performs a reassignment of the switches in order to balance the loads between the controllers. We provide a two-phase algorithm, called Dynamic Controllers Clustering algorithm, for the top level of load balancing operation. The load balancing operation takes place at regular intervals. The length of the cycle in which the operation is performed can be shorter, since the top-level operation can run independently of the bottom level operation. Shortening cycle time allows for more accurate results of load balancing. Theoretical analysis demonstrates that our algorithm provides a near-optimal solution. Simulation results show that our dynamic clustering improves fixed clustering by a multiplicative factor of 5.

An economic framework for analysis of network architectures: SDN and MPLS cases

As new networking architectures such as 5G start materializing in the next era of communication revolution, economic and operational facets of these future networks drive researchers to rethink about their capabilities of flexibility, agility, programmability, and cost-effectiveness. These are the main features to make networks like 5G (fifth-generation) possible and available for societies shortly because they are the fundamental catalysts to achieve economic success in a network. It is vital for network owners to analyze and understand economic aspects of a network architecture before deciding to invest in it. In this article, we introduce a framework utilizing an activity-based approach for the techno-economic analysis of network architectures. In particular, we perform an economic analysis of SDN (Software Defined Networking) technology and MPLS (Multiprotocol Label Switching) technology in order to understand how programmable networking, i.e., SDN technology, affects the network economics compared to traditional networking, i.e., MPLS technology. To this end, we firstly conduct a quantitative analysis exploiting an activity-based approach for CAPEX (Capital Expenditure) and OPEX (Operational Expenditure) calculations of a network. Secondly, we evaluate the architectures above concerning their economic performances using two metrics: Unit Service Cost Scalability metric and Cost-to-Service metric. Also, we present mathematical models to calculate certain cost parts of a network. Also, we compare different popular SDN control plane models, Centralized Control Plane (CCP), Distributed Control Plane (DCP), and Hierarchical Control Plane (HCP), to understand their economic impact with regards to the defined metrics. We use video as the service with different traffic patterns for the comparison. This work aims at being a useful primer to providing insights regarding which technology and control plane model(s) are appropriate for a specific service, i.e., video, for network owners to plan their investments.