Cen Chen

Demonstration of Cooperative Resource Allocation in an OpenFlow-Controlled Multidomain and Multinational SD-EON Testbed

The combination of elastic optical networks (EONs) and software-defined networking (SDN) leads to SD-EONs, which bring a new opportunity for enhancing programmability and flexibility of optical networks with more freedom for network operators to customize their infrastructure dynamically. In this paper, we investigate how to apply multidomain scenarios to SD-EONs. We design the functionalities in the control plane to facilitate multidomain tasks, and propose an interdomain protocol to enable OpenFlow controllers in different SD-EON domains to operate cooperatively for multidomain routing and spectrum assignment. The proposed system is implemented and experimentally demonstrated in a multinational SD-EON control plane testbed that consists of two geographically distributed domains located in China and USA, respectively. Experimental results indicate that the proposed system performs well for resource allocation across multiple SD-EON domains.

OpenFlow-assisted online defragmentation in single-/multi-domain software-defined elastic optical networks [invited]

Spectrum fragmentation limits the efficiency of spectrum utilization in elastic optical networks (EONs). This paper studies how to take advantage of the centralized network control and management provided by software-defined EONs (SD-EONs) for realizing OpenFlow-assisted implementation of online defragmentation (DF). We first discuss the overall system design and OpenFlow protocol extensions to support efficient online DF and conduct DF experiments with routing and spectrum assignment (RSA) reconfigurations in a single-domain SD-EON. Then, we propose to realize fragmentation-aware RSA (FA-RSA) in multi-domain SD-EONs with the cooperation of multiple OpenFlow controllers. In order to provision inter-domain lightpaths with restricted domain visibility on intradomain resource utilization, we design and implement an inter-domain protocol to facilitate FA-RSA in multi-domain SD-EONs and demonstrate controlling the spectrum fragmentation on inter-domain links with FA-RSA. Our experimental results indicate that the OpenFlow-controlled DF systems perform well and can improve the performance of SD-EONs effectively.

Flexible Availability-Aware Differentiated Protection in Software-Defined Elastic Optical Networks

Availability-aware service provisioning tries to satisfy the availability requirements of clients on demand and can improve the resource efficiency in optical networks. This paper studies the problem of flexible availability-aware differentiated protection (ADP) in elastic optical networks (EONs). We first consider the unique features in EONs, e.g., flexible spectrum allocation and bandwidth-squeezed protection, describe the problem of ADP, and present a theoretical analysis on service availability. Then, we develop an ADP algorithm that can change the path protection scheme to adapt to different service availability requirements. An availability-aware backup reprovisioning strategy is also proposed as a supplement of the ADP algorithm to further improve the protection efficiency. We also discuss the system design for OpenFlow-based software-defined EON (SD-EON) framework to facilitate the ADP scheme. Finally, to demonstrate the overall design, we construct an SD-EON control plane testbed that consists of 14 standalone nodes, implement the proposed algorithms in the OpenFlow controller, and perform experiments to evaluate their performance. The results indicate that the system performs well, and the proposed algorithms can reduce blocking probability effectively without sacrificing the service availability of requests.

Demonstration of online spectrum defragmentation enabled by OpenFlow in software-defined elastic optical networks

We propose and experimentally demonstrate a control-plane framework to realize online spectrum defragmentation (DF) in software-defined elastic optical networks. Experimental results show that the spectrum DF enabled by OpenFlow reduces the blocking probability effectively.

Demonstrations of Efficient Online Spectrum Defragmentation in Software-Defined Elastic Optical Networks

Elastic optical networks (EONs) facilitate agile spectrum management in the optical layer. When coupling with software-defined networking, they function as software-defined EONs (SD-EONs) and provide service providers more freedom to customize their infrastructure dynamically. In this paper, we investigate how to overcome spectrum fragmentation in SD-EONs with OpenFlow-controlled online spectrum defragmentation (DF), and conduct system implementations to facilitate highly-efficient online DF. We first consider sequential DF, i.e., the scenario that involves a sequence of lightpath reconfigurations to progressively consolidate the spectrum utilization. We modify our previous DF algorithm to make sure that the reconfigurations can be performed in batches and the “make-before-break” scheme can be applied to all of them. The modified algorithm is implemented in an OpenFlow (OF) controller, and we design OF extensions to facilitate synchronous batch reconfiguration. Then, we further simplify the DF operations by designing and implementing parallel DF that can accomplish all the DF-related lightpath reconfigurations simultaneously. All these DF implementations are experimentally demonstrated in an SD-EON control plane testbed that consists of 14 stand-alone OF agents and one OF controller, which are all implemented based on high-performance Linux servers. The experimental results indicate that our OF-controlled online DF implementations perform well and can improve network performance in an efficient way.

Leveraging master-slave OpenFlow controller arrangement to improve control plane resiliency in SD-EONs.

In this paper, we study how to improve the control plane resiliency of software-defined elastic optical networks (SD-EONs) and design a master-slave OpenFlow (OF) controller arrangement. Specifically, we introduce two OF controllers (OF-Cs), i.e., the master and slave OF-Cs, and make them work in a collaborative way to protect the SD-EON against controller failures. We develop a controller communication protocol (CCP) to facilitate the cooperation of the two OF-Cs. With the CCP, the master OF-C (M-OF-C) can synchronize network status to the slave OF-C (S-OF-C) in real time, while S-OF-C can quickly detect the failure of M-OF-C and take over the network control and management (NC&M) tasks timely to avoid service disruption. We implement the proposed framework in an SD-EON control plane testbed built with high-performance servers, and perform NC&M experiments with different network failure scenarios to demonstrate its effectiveness. Experimental results indicate that the proposed system can restore services in both the data and control planes of SD-EON jointly while maintaining relatively good scalability. To the best of our knowledge, this is the first demonstration that realizes control plane resiliency in SD-EONs.

Implementation and Demonstration of Revenue-Driven Provisioning for Advance Reservation Requests in OpenFlow-Controlled SD-EONs

This paper aims to realize OpenFlow-controlled revenue-driven advance reservation (AR) provisioning in software-defined elastic optical networks (SD-EONs). We design control plane framework, propose two algorithms for the OpenFlow controller, implement the whole system in a semi-practical SD-EON testbed, and conduct experiments with two payment models. Experimental results indicate the proposed system performs well and can increase total revenue-gain effectively.

Demonstration of OpenFlow-controlled cooperative resource allocation in a multi-domain SD-EON testbed across multiple nations

We propose an inter-domain protocol (IDP) that enables cooperative resource allocation for secure and impairment-aware lightpath provisioning across multiple domains. The proposed IDP is implemented and experimentally demonstrated in a China-USA multi-domain control-plane SD-EON testbed.

Design and Demonstration of SDN-Based Flexible Flow Converging with Protocol-Oblivious Forwarding (POF)

With the development of software-defined networking (SDN), people start to realize that the protocol-dependent nature of OpenFlow, i.e., the matching fields are defined according to existing network protocols (e.g., Ethernet and IP), will limit the programmability of forwarding plane and cause scalability issues. In this work, we focus on Protocol-Oblivious Forwarding (POF) [1], which can make the forwarding plane reconfigurable, programmable and future-proof with a protocol-independent instruction set. We design and implement a POF-based flexible flow converging (F-FC) scheme to reduce the number of flow-entries for enhanced scalability. To evaluate the POF system experimentally, we build a network testbed that consists of both commercial and software-based POF switches. Network experiments with real-time video streaming in the proposed POF system demonstrate that our POF-based F-FC approach can outperform conventional schemes.

Brokered Orchestration for End-to-End Service Provisioning Across Heterogeneous Multi-Operator (Multi-AS) Optical Networks

This paper proposes a new networking paradigm introducing the broker-plane above the management planes of Autonomous Systems (ASes). The brokers communicate with the manager of each AS to assist coordinate end-to-end resource management and path provisioning across the multi-AS networks involving multiple operators. The broker plane updates the virtual network topology, manages the resource information of inter-AS links and aggregated (abstracted) intra-AS links, and computes end-to-end routing, modulation formats, and spectrum assignment (RMSA). Notwithstanding, due to the different dynamicity of each AS, the probability of finding a multi-AS transparent path fulfilling the spectrum continuity and contiguity constraints might be low. To improve the grade of the inter-domain connectivity service, spectrum converters can be installed in inter-domain nodes or per-AS defragmentation can be performed with a global view. In this paper, we introduce a mechanism where each AS can advertise its internal capabilities, e.g., spectrum conversion, their ability to implement spectrum defragmentation or any other network feature. The Multi-AS RMSA with Defragmentation Capability problem is presented and mathematically modeled. A heuristic algorithm is designed to solve it. The mechanisms workflow is comprehensively tested using simulations. Results show connection blocking reduction as high as 26%, clearly validating the benefits of the proposed mechanism. Finally, its experimental assessment was conducted on a distributed multi-continental testbed.