Application-based Network Operations Research Articles

Network service orchestration standardization: A technology survey

Network services underpin operator revenues, and value-added services provide income beyond core (voice and data) infrastructure capability. Today, operators face multiple challenges: a need to innovate and offer a wider choice of value-added services, whilst increasing network scale, bandwidth and flexibility. They must also reduce operational costs, and deploy services far faster - in minutes rather than days or weeks.In the recent years, the network community, motivated by the aforementioned challenges, has developed production network architectures and seeded technologies, like Software Defined Networking, Application-based Network Operations and Network Function Virtualization. These technologies enhance the highly desired properties for elasticity, agility and cost-effectiveness in the operator environment. A key requirement to fully exploit the benefits of these new architectures and technologies is a fundamental shift in management and control of resources, and the ability to orchestrate the network infrastructure: coordinate the instantiation of high-level network services across different technological domains and automate service deployment and re-optimization.This paper surveys existing standardization efforts for the orchestration - automation, coordination, and management - of complex set of network and function resources (both physical and virtual), and highlights the various enabling technologies, strengths and weaknesses, adoption challenges for operators, and areas where further research is required.

Monitoring Plane Architecture and OAM Handler

The increase of new services such as content distribution and interdata center connectivity poses new requirements on the control and management of next generation networks. The application-based network operations (ABNO) is emerging as a paradigm integrating control and management functions for different types of services. Key functionalities lie in the ABNO operation, administration, maintenance (OAM) handler which is responsible for the verification and the actual maintenance of network services following specific service level agreements. The OAM handler collects and correlates alerts about potential problems and triggers actions to preserve services in case of failures or degradations. In this paper, a hierarchical monitoring architecture is presented. The architecture is proposed by building on the OAM handler functionalities. Monitoring information can be filtered and correlated at each hierarchical level guaranteeing high scalability of the management plane. Actions can be taken at each hierarchical layer based on the type of failure and of affected service. Measurements on a commercial systems are carried on to identify the generated alarms upon failure. Then, simulations show the high scalability achieved by the proposed architecture.

SDN orchestration architectures and their integration with Cloud Computing applications

Emerging cloud-based applications, running in geographically distributed data centers (DCs), generate new dynamic traffic patterns which claim for a more efficient management of the traffic flows. Geographically distributed DCs interconnection requires automatic and more dynamic provisioning and deletion of end-to-end (E2E) connectivity services, through heterogeneous network domains. Each network domain may use a different data transport technology but also a different control/management system. The fast development of Software Defined Networking (SDN) and the interworking with current control plane technologies such as Generalized Multi-protocol Label Switching (GMPLS), demand orchestration over the heterogeneous control instances to provide seamless E2E connectivity services to external applications (i.e. Cloud Computing applications).In this work, we present different orchestration architectures based on the SDN principles which use the Path Computation Element (PCE) as a fundamental component. In particular, a single SDN controller orchestration approach is compared with an orchestration architecture based on the Application Based Network Operations (ABNO) defined within the International Engineering Task Force (IETF), in order to find the potential benefits and drawbacks of both architectures. Finally, the SDN IT and Network Orchestration (SINO) platform which integrates the management of Cloud Computing infrastructure with the network orchestration, it is used to validate both architectures by evaluating their performance providing two inter-DC connectivity services: E2E connectivity and Virtual Machine (VM) migration.

Dynamic Virtual Network Reconfiguration Over SDN Orchestrated Multitechnology Optical Transport Domains

Network virtualization is an emerging technique that enables multiple tenants to share an underlying physical infrastructure, isolating the traffic running over different virtual infrastructures/tenants. This technique aims to improve network utilization, while reducing the complexities in terms of network management for operators. Applied to this context, software-defined networking (SDN) paradigm can ease network configurations by enabling network programability and automation, which reduces the amount of operations required from both service and infrastructure providers. SDN techniques are decreasing vendor lock-in issues due to specific configuration methods or protocols. Application-based network operations (ABNO) are a toolbox of key network functional components with the goal of offering application-driven network management. Service provisioning using ABNO may involve direct configuration of data plane elements or delegate it to several control plane modules. We validate the applicability of ABNO to multitenant virtual networks in multitechnology optical domains based on two scenarios, in which multiple control plane instances are orchestrated by the architecture. Congestion detection and failure recovery are chosen to demonstrate fast recalculation and reconfiguration, while hiding the configurations in the physical layer from the upper layer.

ABNO-driven content distribution in the telecom cloud

As current traffic growth is expected to strain capacity of today׳s metro network, novel content distribution architectures where contents are placed closer to the users are being investigated. In that regard, telecom operators can deploy datacenters (DCs) in metro areas, thus reducing the impact of the traffic between users and DCs. In this paper, a hierarchical content distribution architecture for the telecom cloud is investigated: core DCs placed in geographically distributed locations, are interconnected through permanent “per content provider” (CP) virtual network topologies (CP-VNT); additionally, metro DCs need to be interconnected with the core DCs. CP׳s data is replicated in the core DCs through the CP-VNTs, while metro-to-core (M2C) anycast connections are established periodically for content synchronization. Since network failures might disconnect the CP-VNTs, recovery mechanisms are proposed to reconnect both topologies and anycast connections. Topology creation, anycast provisioning, and recovery problems are first formally stated and modeled as Integer Linear Programs (ILP) and heuristic algorithms are proposed. Exhaustive simulation results show significant improvements in both supported traffic and restorability. Workflows to implement the algorithms within the Applications-based Network Operations (ABNO) architecture and extensions for PCEP are proposed. Finally, the architecture is experimentally validated in UPC's SYNERGY test-bed running our ABNO-based iONE architecture.

Experimental Assessment of ABNO-Driven Multicast Connectivity in Flexgrid Networks

The increasing demand of internet services is pushing cloud services providers to increase the capacity of their data centers (DC) and create DC federations, where two or more cloud providers interconnect their infrastructures. As a result of the huge capacity required for the inter-DC network, the flexgrid optical technology can be used. In such scenario, applications can run in DCs placed in geographically distant locations, and hence, multicast-based communication services among their components are required. In this paper, we study two different approaches to provide multicast services in multilayer scenarios assuming that the optical network is based on the flexgrid technology: 1) establishing a point-to-multipoint optical connection (light-tree) for each multicast request, and 2) using a multipurpose virtual network topology (VNT) to serve both unicast and multicast connectivity requests. When that VNT is not able to serve an incoming request as a result of lack of capacity, it is reconfigured to add more resources. A control plane architecture based on the applications-based network operations (ABNO) one, currently being standardized by the IETF, is presented; workflows are proposed and PCEP extensions are studied for the considered approaches. The experimental validation is carried-out on a testbed setup connecting Telefonica, CNIT, and UPC premises.

First Experimental Assessment of ABNO-Driven In-Operation Flexgrid Network Re-Optimization

Traffic affected by link failures can be recovered using path restoration schemes. In dynamically operated networks provided with a control plane, restoration algorithms run in a centralized element, such as the path computation element (PCE). To increase traffic restorability in flexgrid networks, multiple paths, subconnections , can be used to restore every single affected connection. However, the multipath restoration scheme might result in a poor resource utilization entailing a lesser grade of service. In-operation network planning algorithms can be used to mitigate this problem once the failed link is repaired; we propose solving the so-called multipath after failure repair optimization problem (MP-AFRO) to reduce subconnections count by aggregating those belonging to the same original connection and rerouting the resulting connection to release spectral resources. The MP-AFRO problem is modeled using a mixed integer linear program formulation. In view of the complexity of the model and the limited time to solve the problem, we propose a heuristic algorithm that provides a good tradeoff between complexity and optimality. The performance on the MP-AFRO heuristic is firstly validated by simulation. Next, the heuristic algorithm is deployed inside an in-operation planning tool in the form of back-end PCE (bPCE) inside the application-based network operations architecture controlling a network; the bPCE is connected to the centralized active stateful PCE. MP-AFRO is experimentally demonstrated using a distributed field trial test-bed connecting the premises of Telefonica (Madrid), CNIT (Pisa), and UPC (Barcelona).

Transport Network Orchestration for End-to-End Multilayer Provisioning Across Heterogeneous SDN/OpenFlow and GMPLS/PCE Control Domains

A multidomain optical transport network composed of heterogeneous optical transport technologies (e.g., flexi/fixed-grid optical circuit switching and optical packet switching) and control plane technologies (e.g., centralized OpenFlow or distributed GMPLS) does not naturally interoperate, and a network orchestration mechanism is required. A network orchestrator allows the composition of end-to-end network service provisioning across multidomain optical networks comprising different transport and control plane technologies. Software-defined networking (SDN) is a key technology to address this requirement, since the separation of control and data planes makes the SDN a suitable candidate for end-to-end provisioning service orchestration across multiple domains with heterogeneous control and transport technologies. This paper presents two different network orchestration's architectures based on the application-based network operations (ABNO) which is being defined by IETF based on standard building blocks. Then, we experimentally assesses in the international testbed of the STRAUSS project, an ABNO-based network orchestrator for end-to-end multi-layer (OPS and Flexi-grid OCS) and multidomain provisioning across heterogeneous control domains (SDN/OpenFlow and GMPLS/Stateful PCE) employing dynamic domain abstraction based on virtual node aggregation.

ABNO: A Feasible SDN Approach for Multivendor IP and Optical Networks [Invited

Software defined networking (SDN) and network programmability offer the ability to direct application service requests toward the IP/MPLS and optical network. The SDN approach can help operators to reduce the CAPEX and OPEX in the networks, thanks to the optimization of the resources and the reduction of the complexity in the operation of the network. However, the proposed SDN controllers in the market are based on monolithic software, which is not adapted to current heterogeneous network environments. Such SDN solutions are like a “black box,” and their deployment leads to different problems for the operator: 1) vendor lock-in (solutions in the market are mono-vendor); 2) lack of support with non-OpenFlow networks; and 3) problems in supporting E2E multidomain path establishment in current networks. The application-based network operations (ABNO) architecture is proposed in IETF as a framework that enables network automation and programmability thanks to the utilization of standard protocols and components. This work not only justifies the architecture but also presents an experimental demonstration for a multilayer and multitechnology scenario.

SDN-Based Network Orchestration of Variable-Capacity Optical Packet Switching Network Over Programmable Flexi-Grid Elastic Optical Path Network

A multidomain and multitechnology optical network orchestration is demonstrated in an international testbed located in Japan, the U.K., and Spain. The application-based network operations architecture is proposed as a carrier software-defined network solution for provisioning end-to-end optical transport services through a multidomain multitechnology network scenario, consisting of a 46-108 Gb/s variable-capacity OpenFlow-capable optical packet switching network and a programmable, flexi-grid elastic optical path network.

Managing transfer-based datacenter connections

Creating datacenter federations allows balancing workloads accommodating spikes in cloud demand while reducing the extensive energy consumption of datacenters. This allows datacenter operators to reduce cost and increase their revenue from using under-utilized resources. To implement those elastic operations, datacenters need to be connected through a network providing huge capacity and guaranteeing adequate resource availability when it is required. Those features can be covered by the flexgrid optical technology provided with an intelligent control plane. For the latter, in this paper we rely on the application-based network operations (ABNO) architecture currently under standardization in the IETF. To increase the availability of the desired capacity, a carrier software defined network (SDN) is placed on top of ABNO. On this architecture, cloud resource managers request data transferences using an application-oriented semantic, which includes data volume and required completion time. Those requests are transformed into connection requests by the carrier SDN. To increase resource availability for incoming requests, the carrier SDN can perform elastic operations on already established connections supporting transferences provided that the committed completion time is ensured. Requests are routed and resource allocation is scheduled, which becomes the routing and scheduled spectrum allocation (RSSA) problem. An integer linear programming model is proposed, and an algorithm for solving the RSSA problem in realistic scenarios is designed. Results showing remarkable gains in the amount of data transported motivate its use for inter-datacenter traffic.

Managing Transfer-Based Datacenter Connections

Creating datacenter federations allows balancing workloads accommodating spikes in cloud demand while reducing the extensive energy consumption of datacenters. This allows datacenter operators to reduce cost and increase their revenue from using under-utilized resources. To implement those elastic operations, datacenters need to be connected through a network providing huge capacity and guaranteeing adequate resource availability when it is required. Those features can be covered by the flexgrid optical technology provided with an intelligent control plane. For the latter, in this paper we rely on the application-based network operations (ABNO) architecture currently under standardization in the IETF. To increase the availability of the desired capacity, a carrier software defined network (SDN) is placed on top of ABNO. On this architecture, cloud resource managers request data transferences using an application-oriented semantic, which includes data volume and required completion time. Those requests are transformed into connection requests by the carrier SDN. To increase resource availability for incoming requests, the carrier SDN can perform elastic operations on already established connections supporting transferences provided that the committed completion time is ensured. Requests are routed and resource allocation is scheduled, which becomes the routing and scheduled spectrum allocation (RSSA) problem. An integer linear programming model is proposed, and an algorithm for solving the RSSA problem in realistic scenarios is designed. Results showing remarkable gains in the amount of data transported motivate its use for inter-datacenter traffic.

Experimental assessment of in-operation spectrum defragmentation

Dynamic operation of flexgrid networks might cause optical spectrum to be divided into fragments, which makes it difficult finding contiguous spectrum of the required width for incoming connection requests, leading thus to an increased blocking probability. To alleviate to some extent that spectrum fragmentation, the central frequency of already established connections can be shifted to create wider contiguous spectrum fragments to be allocated to incoming connections; this procedure is called spectrum defragmentation. In this paper, we propose using the so called applications based network operations (ABNO) architecture, currently under standardization in the IETF, to deal with the defragmentation use case while the network is in operation. A workflow involving several elements in the ABNO architecture is proposed and experimentally assessed in a distributed test bed connecting facilities in three major European cities.