PCEP Extensions for WSON Impairments (original) (raw)
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A Framework for the Control of Wavelength Switched Optical Networks (WSONs) with Impairments
2012
As an optical signal progresses along its path, it may be altered by the various physical processes in the optical fibers and devices it encounters. When such alterations result in signal degradation, these processes are usually referred to as "impairments". These physical characteristics may be important constraints to consider when using a GMPLS control plane to support path setup and maintenance in wavelength switched optical networks. This document provides a framework for applying GMPLS protocols and the Path Computation Element (PCE) architecture to support Impairment-Aware Routing and Wavelength Assignment (IA-RWA) in wavelength switched optical networks. Specifically, this document discusses key computing constraints, scenarios, and architectural processes: routing, wavelength assignment, and impairment validation. This document does not define optical data plane aspects; impairment parameters; or measurement of, or assessment and qualification of, a route; rather, it describes the architectural and information components for protocol solutions. Lee, et al. Informational [Page 1] RFC 6566 Framework for Optical Impairments March 2012 Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6566.
2011
This document provides a framework for applying Generalized Multi-Protocol Label Switching (GMPLS) and the Path Computation Element (PCE) architecture to the control of Wavelength Switched Optical Networks (WSONs). In particular, it examines Routing and Wavelength Assignment (RWA) of optical paths. This document focuses on topological elements and path selection constraints that are common across different WSON environments; as such, it does not address optical impairments in any depth. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6163\. Lee, et al.
Optical Switching and Networking, 2013
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.
Demonstration of Flexible Optical Network Based on Path Computation Element
Journal of Lightwave Technology, 2000
Flexible optical networks, based on bandwidth-variable optical cross-connects (BV-OXCs) and novel flexible transponders, are expected to significantly improve the overall spectrum efficiency with respect to traditional networks where fixed frequency spacing is applied. Flexible optical networks will exploit the BV-OXC capability to dynamically configure the reserved bandwidth as a set of frequency slots. In addition, flexible transponders will be employed to dynamically configure transmission parameters, such as bit-rate and modulation format. To enable these new configuration capabilities, network operation enhancements need to be efficiently introduced and investigated. In this study, we focus for the first time on the Path Computation Element (PCE) architecture for flexible optical networks. PCE architecture and PCE communication protocol are enhanced to maximize the spectral efficiency and to provide indications also on the specific transmission parameters to configure. Experimental demonstration is provided through two different experiments, successfully showing the PCE capability to trigger dynamic rerouting with bit-rate or modulation format adaptation. In particular, the experiments demonstrate, in a real testbed, dynamic frequency slot assignment and format adaptation from DP-16QAM to DP-QPSK at 100 Gb/s, and bit-rate adaptation at DP-16QAM from 200 Gb/s to 100 Gb/s.
Requirements for GMPLS Applications of PCE
2013
The initial effort of the PCE (Path Computation Element) WG focused mainly on MPLS. As a next step, this document describes functional requirements for GMPLS applications of PCE. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7025.
Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks
2015
This document provides efficient, protocol-agnostic encodings for the WSON-specific information fields. It is intended that protocolspecific documents will reference this memo to describe how information is carried for specific uses. Such encodings can be used to extend GMPLS signaling and routing protocols. In addition, these encodings could be used by other mechanisms to convey this same information to a Path Computation Element (PCE). Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7581.
PCE: What is It, How Does It Work and What are Its Limitations?
Journal of Lightwave Technology, 2000
In GMPLS-controlled optical networks, the utilization of source-based path computation has some limitations, especially in large networks with stringent constraints (e.g. optical impairments) or in multi-layer and multi-domain networks, which leads to sub-optimal routing solutions. The Path Computation Element (PCE) can mitigate some weaknesses of GMPLS-controlled optical networks. The main idea behind the PCE is to decouple the path computation function from the GMPLS controllers into a dedicated entity with an open and well-defined interface and protocol. A (stateless) PCE is capable of computing a network path or route based on a network graph (i.e., the Traffic Engineering Database-TED) and applying computational constraints. First, we present an overview of the PCE architecture and its communication protocol (PCEP). Then, we present in detail the considered source-routing shortcomings in GMPLS-controlled networks, namely, impairment-aware path computation, multi-domain path computation and multi-layer path computation, as well as the different PCE-based solutions that have been proposed to overcome each one of these problems. However, PCE-based computation also presents some limitations that lead to an increase in the path computation blocking or to sub-optimal path computations. The stateful PCE overcomes the limitations of the stateless PCE, such as the outdated TED, the lack of global LSP state (i.e., set of computed paths and reserved resources in use in the network), and the lack of control of path reservations. A passive stateful PCE allows optimal path computation and increased path computation success, considering both the network state (TED) and the Label Switched Paths (LSP) state (LSP Database-LSPDB). Additionally, an active stateful PCE can modify existing LSPs (i.e., connections), and optionally, setup and/or release existing LSPs. Finally, the formal decoupling of the path computation allows more flexibility in the deployment of PCEs in other control paradigms outside their original scope (MPLS/GMPLS). In this sense, we provide an overview of three PCE deployment models in the Software Defined Network (SDN) control architecture.
New Technologies and Directions for the Optical Control Plane
Journal of Lightwave Technology, 2012
Distributed control plane technology has been incorporated in many carrier optical networks to improve automation, robustness, and efficiency. Going forward, carriers' interest is shifting from internal domain protocols to interdomain interfaces. Also, new transport technologies being deployed such as optical transport network, packet, and photonic transport need control plane support, while new technologies are being added to the control plane itself, especially path computation elements and multilayer integration tools. Index Terms-Automatic switched optical network (ASON), control plane, generalized multiprotocol label switching (GMPLS), optical.
Cognitive Dynamic Optical Networks [Invited]
Journal of Optical Communications and Networking, 2013
The use of cognition is a promising element for the control of heterogeneous optical networks. Not only are cognitive networks able to sense current network conditions and act according to them, but they also take into account the knowledge acquired through past experiences; that is, they include learning with the aim of improving performance. In this paper, we review the fundamentals of cognitive networks and focus on their application to the optical networking area. In particular, a number of cognitive network architectures proposed so far, as well as their associated supporting technologies, are reviewed. Moreover, several applications, mainly developed in the framework of the EU FP7 Cognitive Heterogeneous Reconfigurable Optical Network (CHRON) project, are also described.
Challenges and requirements of a control plane for elastic optical networks
Computer Networks, 2014
Elastic Optical Networks have emerged as a promising technology for the efficient use of optical network resources. Its adaptable characteristics and adjustable data rate enable operators to meet the diverse granularity of their clients needs. In order to automate an elastic optical network operation, a control plane is required. Wavelength Switched Optical Networks (WSON) may already rely on a robust control plane which enables dynamic network management, provides prompt demand reply optimizing spectrum use, and implements important network features as survivability strategies, differentiated service, and grooming procedures. Due to its specific characteristics, Elastic Optical Networks may not implement traditional WSON control plane solutions without further enhancement. Therefore, recent research efforts have been focusing on developing the control plane for this new technology, in most cases by proposing extensions to the currently available architectures. This paper describes a survey on the current ongoing research efforts to define Elastic Optical Network control plane architecture. It identifies and classifies the most relevant proposals currently found in literature, and discusses how these propositions address the main requirements to design a control plane which enables automating the specific functions of an Elastic Optical Network.