Generalized Multiprotocol Label Switching Control Plane Research Articles

Optical Power Control in Translucent Flexible Optical Networks With GMPLS Control Plane

The continuously increasing traffic of Internet services (cloud services, video streaming, social networks, and recently, Internet of Things services) is leading to huge traffic growth in core optical networks. This traffic evolution is pushing network operators to efficiently exploit their infrastructures in order to postpone, as much as possible, the expensive deployment of new infrastructures. In this respect, the migration from fixed-to flex-grid optical networks was triggered in order to efficiently use optical network capacity, taking benefits from the improved spectral efficiency of flexible transponders. In our previous work [J. Opt. Commun. Netw., vol. 8, no. 8, p. 553, Aug. 2016], we demonstrated that migrating towards flexible networks while keeping in use existing optical amplifiers will cause a power saturation problem over highly loaded links due to the increase in the number of optical channels. To overcome this problem, we proposed in that work a power adaptation process that consists of converting transmission performance margins into optical power attenuation over optical links. However, the realized work considered only a transparent optical network controlled by the generalized multiprotocol label switching (GMPLS) protocol suite. In this paper, we consider the case of a translucent optical network where optical regeneration is required, and thus, the power adaptation process is adapted to this kind of network. A new routing algorithm and protocol extensions are proposed to take into account power and regeneration information in the GMPLS control plane of translucent networks.

A Hybrid Method for Signalling Transport in GMPLS Control Plane

This paper addresses the issue of signalling transport in control plane of the Generalized Multi-Protocol Label Switching (GMPLS) network. The two basic methods for establishing control channels in optical networks are the in-fibre-out-of-band and the out-of-fibre. Starting from the analysis of benefits and drawbacks of those methods, we propose and investigate a novel, flexible method for signalling transport, which is based on the analysis of the given network topology and combines the basic methods to achieve a trade-off between requirements for low latency and high reliability. Performance analysis has shown that, with hybrid method, data path setup times are close to the ones achieved with the in-fibre-out-of-band method, while preserving satisfying reliability and flexibility to integrate into multi-domain networks.DOI: http://dx.doi.org/10.5755/j01.eie.22.3.15310

Overarching Control of Flexi Grid Optical Networks: Interworking of GMPLS and OpenFlow Domains

Optical transport networks provide transport, multiplexing, routing, management, supervision, and survivability of optical channels. Within a flexible dense wavelength division multiplexing grid, the optical spectrum can be allocated in multiples of a width granularity, depending on the client signal rate and modulation format. A control plane (CP) can be used for efficient and dynamic provisioning and recovery of flexi-grid connections. Two main CP architectures coexist, with common functions like addressing, automatic topology discovery, network abstraction, path computation, and connection provisioning: a distributed generalized multiprotocol label switching CP (with optional path computation element, PCE path computation and instantiation/modification) and a CP based on software-defined networking, with a logically centralized controller and an open protocol, such as the OpenFlow protocol. Both architectures have their own strengths and weaknesses, and are being extended to address the new requirements associated with the aforementioned emerging optical technologies, such as flexible spectrum allocation, efficient corouted connection setup, and configuration of related optical parameters. However, new use cases such as remote data center interconnection highlight the need for multidomain service provisioning, and heterogeneous CP interworking, potentially requiring an overarching control. Different alternatives, with varying degrees of integration and flexibility, are available: straightforward approaches characterized by the adaptation of one control model to the other or more advanced interworking requiring the definition of common models (e.g., a subset of attributes for network elements) and of coordination and orchestration functions. This paper discusses the main relevant interworking architectures and presents a selected set of use cases and proof-of-concepts.

GMPLS Control Plane With Distributed Multipath RMSA for Elastic Optical Networks

Elastic optical networking (EON) has the constraint that all flows must have contiguous allocated frequency slots across all fiber links end-to-end, hence, the routing, modulation and spectrum assignment (RMSA) is one of the most important considerations in EON. This paper proposes and demonstrates a design of a generalized multiprotocol label switching (GMPLS) control plane for EON with distributed RMSA. The proposed approach uses an extended RSVP-TE to find multipath by broadcasting PATH message, using tentative reservation to avoid setting up multipath for one request. The proposed method also overcomes challenges faced by the previously pursued GMPLS-EON methods which relied on dynamic OSPF-TE where control plane overhead and the collision among lightpath requests caused by signaling latency. Simulation results based on the proposed GMPLS-EON method on different network scenarios reveal that our proposed design reduces the blocking probability by 4.56 and 3.86 when compared with the conventional GMPLS and GMPLS/PCE approaches, respectively, in the NSF topology at the network offered load of 60 Erlang. It also reduces signaling time by a factor of 1.84 compared with conventional GMPLS/PCE approach in the same network condition.

Dynamic and Adaptive Control Plane Solutions for Flexi-Grid Optical Networks Based on Stateful PCE

Adaptive flexi-grid optical networks should be able to autonomously decide where and when to dynamically setup, reoptimize, and release elastic optical connections, in reaction to network state changes. A stateful path computation element (PCE) is a key element for the introduction of dynamics and adaptation in generalized multiprotocol label switching (GMPLS)-based distributed control plane for flexi-grid DWDM networks (e.g., global concurrent reoptimization, defragmentation, or elastic inverse-multiplexing), as well as for enabling the standardized deployment of the GMPLS control plane in the software defined network control architecture. First, this paper provides an overview of passive and active stateful PCE architectures for GMPLS-enabled flexi-grid DWDM networks. A passive stateful PCE allows for improved path computation considering not only the network state (TED) but also the global connection state label switched paths database (LSPDB), in comparison with a (stateless) PCE. However, it does not have direct control (modification, rerouting) of path reservations stored in the LSPDB. The lack of control of these label switched paths (LSPs) may result in the suboptimal performance. To this end, an active stateful PCE allows for optimal path computation considering the LSPDB for the control of the state (e.g., increase of LSP bandwidth, LSP rerouting) of the stored LSPs. More recently, an active stateful PCE architecture has also been proposed that exposes the capability of setting up and releasing new LSPs. It is known as active stateful PCE with instantiation capabilities. This paper presents the first prototype implementation and experimental evaluation of an active stateful PCE with instantiation capabilities for the GMPLS-controlled flexi-grid DWDM network of the ADRENALINE testbed.

Design of a GMPLS control plane with PCE-based impairment-aware full restoration capability for translucent WSON: Enabling techniques, service demonstration, and performance evaluation

The control plane techniques based on the Generalized Multi-Protocol Label Switching (GMPLS) and Path Computation Element (PCE) architectures are promising candidates for potential industrial deployment in Wavelength Switched Optical Networks (WSON), because they can greatly reduce operational expenses and improve the network intelligence. Moreover, link failures have a critical effect on WSON, since a single failure may result in the loss of a huge amount of data. In light of this, in this paper, we detail the design and implementation of a GMPLS control plane, with PCE-based, impairment-aware, full restoration capability for translucent WSON. We investigate the enabling techniques for such a PCE/GMPLS control plane by surveying a series of solutions, and, based on these enabling techniques, we present an experimental demonstration of service recovery for uncompressed video stream in a GMPLS controlled WSON with PCE-based full lightpath restoration. We also quantitatively evaluate the performance of the PCE-based full restoration, and compare it with the PCE-based pre-planned restoration and the PCE-based pre-computed dynamic restoration in terms of signaling latency and restorability. To the best of our knowledge, it is the first time that the PCE-based full restoration is experimentally investigated on an actual GMPLS controlled WSON testbed, which is beneficial for verifying the overall feasibility and efficiency of the proposed solutions, obtaining valuable insights for its future deployment in a real operational scenario, and providing active contribution in support of the on-going Internet Engineering Task Force (IETF) standardization activities.

Experimental Demonstration of Highly Resilient Wavelength-Switched Optical Networks With a Multivendor Interoperable GMPLS Control Plane

The backbone infrastructure for providing carrier-class services, such as a wavelength-switched optical network (WSON), usually involves equipment from multiple vendors. For intelligent path control in the WSON, it is highly desirable to introduce a unified generalized multiprotocol label switching (GMPLS) control plane, which is beneficial for reducing the operational cost and facilitating the dynamic service recovery. However, the interoperability issue of GMPLS-enabled WSON among multiple vendors has not been investigated to date, preventing its wide deployment in an actual operational scenario. Accordingly, in this paper, we experimentally present a highly resilient WSON with a multivendor interoperable GMPLS control plane. We successfully verify the interworking of the GMPLS control plane and wavelength-switching equipment from multiple vendors, and experimentally present dynamic wavelength path control and dynamic lightpath recovery from single-link failures that occur at different times and multiple link failures that occur simultaneously on a multivendor WSON testbed with both control and data planes. To the best of our knowledge, the interoperability trial of GMPLS-controlled WSON is a world first.

Experimental Performance of Shared Path Protection With Flooded Versus Collected Sharing Resource Information in GMPLS WSON Networks

In generalized multiprotocol label switching (GMPLS)-enabled wavelength-switched optical networks (WSONs), shared path protection (SPP) attains 100% survivability with an acceptable recovery time, for lightpaths affected by a single-link failure. This is achieved by sharing backup resources. Nevertheless, neither the standard OSPF-TE nor the RSVP-TE protocols support the respective flooding/collection of shareable resource information for SPP purposes. This prevents the source node from computing backup paths exploiting the SPP advantages, and the destination node from performing optimal wavelength assignment (WA) favoring the reuse of shareable resources. In this paper, we experimentally evaluate, in the GMPLS control plane of the ADRENALINE testbed, the performance improvements when shareable resource information is either flooded (by enhanced OSPF-TE) and/or collected (by enhanced RSVP-TE), under the wavelength continuity constraint. Additionally, we propose efficient SPP path computation and WA algorithms, considering three information dissemination strategies: aggregated unreserved bandwidth, aggregated shared bandwidth, and wavelength-channel granularity.

An analytical model for GMPLS control plane resilience quantification

This paper concentrates on the resilience of the generalized multi-protocol label switching (GMPLS) enabled control plane. To this end, the problem of control plane resilience in GMPLS-controlled networks is firstly stated and previous work on the topic reviewed. Next, analytical formulae to quantify the resilience of generic meshed control plane topologies are derived. The resulting model is validated by simulation results on several reference network scenarios.

Field Trial of All-Optical Networking Controlled by Intelligent Control Plane With Assistance of Optical Performance Monitors

A field trial of all-optical networking by an intelligent control plane based on generalized multiprotocol label switching (GMPLS) technologies was successfully conducted with the assistance of optical performance monitors (OPMs) capable of monitoring the in-band optical signal-to-noise ratio (OSNR). In the field trial, the GMPLS control plane was applied to not only fast provisioning of all-optical paths but also to end-to-end restoration of optical paths triggered by OPMs. Reliable and stable network operation was achieved as a result of applying the GMPLS control plane and OPMs.

Multi-ASON and GMPLS network domain interworking challenges

This article describes the intercarrier external network-to-network interface development challenges at the Kei-han-na Info-Communications Open Laboratory. The E-NNI prototype that was developed provides interworking functionality between the automatically switched optical network control plane function of the ITU-T and the generalized multiprotocol label-switching control plane function of the IETF. In this article, an analysis of the differences between ASON network technologies and GMPLS network technologies, a detailed signaling protocol and routing protocol interworking mechanism, and the interworking experimental results of nationwide ASON and GMPLS network domains are described.

All-optical wavelength-path service with quality assurance by multilayer integration system

In the future all-optical network controlled by generalized multiprotocol label switching (GMPLS), the wavelength path between end nodes will change dynamically. This inevitably means that the fiber parameters along the wavelength path will also vary. This variation in fiber parameters influences the signal quality of high-speed-transmission system (bit rates over 40 Gb/s). Therefore, at a path setup, the fiber-parameter effect should be adequately compensated. Moreover, the path setup must be completed fast enough to meet the network-application demands. To realize the rapid setup of adequate paths, a multilayer integration system for all-optical wavelength-path quality assurance is proposed. This multilayer integration system is evaluated in a field trial. In the trial, the GMPLS control plane, measurement plane, and data plane coordinated to maintain the quality of a 40-Gb/s wavelength path that would otherwise be degraded by the influence of chromatic dispersion. It is also demonstrated that the multilayer integration system can assure the signal quality in the face of not only chromatic dispersion but also degradation in the optical signal-to-noise ratio by the use of a 2R regeneration system. Our experiments confirm that the proposed multilayer integration system is an essential part of future all-optical networks.

Value-added proposition of the GMPLS control plane in IP optical networks

We quantify the value-added proposition of the generalized multiprotocol label switching (GMPLS) distributed control plane vis a vis the centralized network management (CNM) plane. Our main objective is not to propose new protocols or algorithms, but rather to provide guidance to network operators on how to maximize the benefits of deploying a GMPLS control plane. We identify two main goals for maximizing these benefits: (1) decreasing operations costs and (2) increasing revenues through enhancing the efficiency of existing network assets as well as through enabling new services. Control plane functionalities such as dynamic routing, user-initiated end-to-end connection setup, and distributed fault management in IP optical networks are analyzed to determine optimal operating regions where their values are maximized. Extensive simulations using NSFNET topology have been carried out from which we have found that there are certain operating regions where (1) the distributed routing can improve the efficiency of network assets by saving 15% of the number of wavelengths per link, or increasing traffic loads by 20%. However, if the call interarrival time is shorter than 1 min, the efficiency (in terms of call blocking ratio) of distributed dynamic routing is reduced due to the OSPF convergence delay. (2) Enabling bandwidth on demand (BoD) services at finer bandwidth granularities connections is more cost-effective to the operator than doing the same at coarse bandwidth granularities. (3) The connection setup delay is the limiting factor in determining the types of BoD services a carrier offers. The call blocking ratio will increase quickly if the average call interarrival time is less than tens of seconds. (4) Assuming only single link failure, M:N shared protection can achieve 100% recovery at the expense of 10% increase in the number of wavelengths compared with nonprotection schemes, while saving are as high as 48% wavelengths compared with 1:1 dedicated protection.

Application of the Link Management Protocol to Discovery and Forwarding Adjacencies

The link management protocol (LMP) is used to maintain control channel connectivity, to verify the physical connectivity of data channels, to correlate link property information at both endpoints of a data link and to aggregate multiple data links into a single traffic engineering (TE) link. LMP also provides assistance in fault localization, both in opaque and transparent optical networks. In this paper, we show how LMP relates to the generalized multi-protocol label switching (GMPLS) suite of protocols and integrates into a distributed GMPLS control plane. We describe the role of LMP in two applications: data link (auto-)discovery and the establishment of forwarding adjacency label-switched paths (FA-LSPs) including their initiation, verification and bundling, and conclude that they can be built upon basic functions of LMP, namely control channel management, link verification and link property correlation.

PNNI-based control plane for automatically switched optical networks

Much effort has been spent on the definition of control plane protocols for automatically switched optical networks (ASON). Most of the proposals brought into the standardization for an International Telecommunications Union-Telecommunication Sector, Internet Engineering Task Force, and Optical Internetworking Forum are based on Internet protocol concepts. One such proposal is the generalized multi-protocol label switching (GMPLS), an extension of the MPLS traffic engineering control plane model that includes nonpacket switched technologies (time, wavelength, and fiber switching). Recently, the potential use of private network-network interface (PNNI) in ASONs has been discussed as an alternative proposal by the standardization bodies. The goal of this paper is to appropriately adapt asynchronous transfer mode into an optical PNNI (O-PNNI) protocol that can be used as the control plane of ASONs. The paper also provides a critical viewpoint on the potential usage of either O-PNNI or GMPLS control plane and analyzes the pros and cons of each. The methodology adopted toward devising O-PNNI hinges on reviewing PNNI along with ASON recommendations in order to determine the set of PNNI features that require adaptation. Having identified these features we engineer and present appropriate solutions relating to routing, signaling and addressing aspects.