Policy approach to managing WDM networks

The paper gives an overview of the automatically switched optical network (ASON), concentrating on its control plane. Drivers for automatically switched optical networks are briefly presented. The ASON architecture, based on transport, control, and management planes, is discussed. Types of connections supported by ASON are described, including permanent, switched, and soft permanent connections. Different kinds of internal and external interfaces are presented. Various issues related to the ASON control plane are enumerated.

In automatic switched transport networks (ASTN), transport services of different granularity can be set up, modified and released on demand, using mechanisms in the control plane. Currently, this novel provisioning paradigm is being standardized under the umbrella of the automatic switched optical network (ASON) and the generalized multiprotocol label switching (GMPLS) framework. This paper gives an overview of the concepts and open issues of ASON and GMPLS at the current stage of their development.

The Automatically Switched Optical Networks (ASONs) and the Generalized Multi Protocol Label Switching (GMPLS) control plane are envisaged to play an important role in the next generation Internet. They provide optical networks with intelligence and automation and they enable the Multilayer Traffic Engineering (MTE) paradigm which facilitates the IP/optical adaptive integrated routing. This paper proposes an adaptive strategy for integrated routing. The routing decision is based on the network state. The strategy either sets up a new lightpath or grooms traffic on the existing virtual topology depending on the resource utilization level experienced on the IP and optical layers. To reduce the quantity of control information, we also propose and evaluate a heuristic that overcomes scalability problems at the expenses of less optimal performance. The proposed strategies are evaluated by means of simulation and they are compared with two non adaptive routing policies widely investigated in literature.

The explosive growth of Internet traffic has led to a dramatic increase in demand for data transmission capacity, which has spurred tremendous research activities in optical transport networks (OTNs) such as automatically switched optical networks (ASON) and related control protocols. To provide high resilience against failures, OTNs must have an ability to maintain an acceptable level of service during network failures. Fast and resource optimized light- path restoration strategies are urgent requirements for the near future OTN with a generalized multi-protocol label switching (GMPLS) control plane. Our objective in this paper is to presents a multi-layer recovery scheme that guarantees fast and efficient recovery of lightpaths in ASON/GMPLS networks. It includes concepts as well as systematic procedures of the proposed scheme for multilayer recovery in ASON/GMPLS networks.

A reliable control plane plays a crucial role in creating high-level services in the next-generation transport network based on the generalized multiprotocol label switching (GMPLS) or automatically switched optical networks (ASON) model. Approaches to control-plane survivability, based on protection, and restoration mechanisms, are examined. Procedures for the control plane state recovery are discussed, including link and node failure recovery

We present policy-based management, based on the IETF framework, of optical networks having a GMPLS (generalized multiprotocol label switching) based control plane to realize integration of the control and management planes. A business model centered on bandwidth trading is used to demonstrate the need for policy-enabled GMPLS (PE-GMPLS) in the "photonic IP" age.

Recent trends in bandwidth markets show that customers are tending to ask providers for a large bandwidth but for a limited amount of time to support new short-term bandwidth-hungry applications. In order to meet these new requirements, progress in network technologies (fast and reconfigurable switching equipment) and protocols [such as generalized multiprotocol label switching (GMPLS) and automatically switched optical network (ASON)] is paving the road towards flexible optical transport networks in which leasable circuits could be set up and released on a short-term basis. As a result, for dynamic traffic, the holding time of connection requests can be known in advance. The authors propose to exploit knowledge of connection holding time to design an efficient algorithm, called PHOTO, for the dynamic provisioning of shared-path-protected connections in optical mesh networks. The core idea of the proposal consists of exploiting the knowledge of the holding time of connection requests to minimize resource overbuild (RO) due to backup capacity and hence achieve resource-usage efficiency. For a typical US nationwide network, savings on RO of up to 10% were obtained for practical scenarios compared to a holding-time-unaware, but otherwise shared-path-efficient, approach.

The present paper presents a framework for managing quality of service in future WDM core optical networks. These networks solve the bandwidth problem but transmit complexity to the control and management layers. Part of this complexity is handled by the generalized multiprotocol label switching (GMPLS) control plane. The latter, however, cannot tackle the new challenges posed by emerging applications requiring more than bandwidth guaranteed connections. In this paper, we first study the requirements of applications and the proposed quality of service in GMPLS, and then, we try to fill up the gap between both, with a focus on the transmission delay. The resulting framework will enable the optical network to meet the exigencies of new services

An automatically switched optical network (ASON) can be used as the transport layer of generalized multiprotocol label switching (GMPLS) networks. The design of an ASON involves determining the number of optical cross-connects (OXC) in the network, the required number of ports per OXC, and the interconnection topology of the OXCs. Given the number of ports per OXC, we present a linear algorithm to find the number of OXCs and to identify a cost-effective topology. We then develop a scheme that can be used to perform waveband grooming for several different topologies of an ASON that uses single-layer multigranular OXCs. We identify the bottlenecks and investigate the effect of traffic grooming schemes in the design of an ASON as a function of the peak access rate per customer. We evaluate the topologies and architectures for a national trunk network.

Due to widespread applications and rapid development of cloud computing and Internet services, hyperscale data centers have experienced an unprecedented demand for networking. Data center networks are required not only to handle fast-growing traffic, which doubles almost every one to two years, but also to provide high flexibility and availability to support rapidly changing businesses as well. Therefore, hyperscale data center networks have become one of the main drivers for optical interconnect technologies in recent years. In this article, technologies for scaling optical interconnects for inter-data center interconnects (DCIs) are presented. We first describe hyperscale data center network architectures and requirements, as well as the differences between carrier’s optical transport networks and DCI optical networks, with the main focus on metro-DCI and campus-DCI networks. The scale and fast growth rates of DCI networks require innovations not only in data plane technologies but also in control and management planes as well. In data planes, high-capacity flexible coherent technology, pluggable wavelength-division-multiplexing (WDM) optical transponders, including 100G direct-detection four-level pulse-amplitude modulation (PAM4) and coherent 400ZR/800ZR, and flex-grid and disaggregated reconfigurable optical add-drop multiplexer (ROADM) optical networks are described. Control and management planes are an integral part of optical transport networks and crucial for effectively operating DCI networks. We show that standard protocols, data models, and modular design of a software platform are essential to building a scalable open and disaggregated optical network, which is fundamental to enabling high automation and intelligence in an optical network. An example control and management platform is discussed in detail. With current fiber capacity approaching the nonlinear Shannon limit, challenges to further scale DCI networks and some potential technologies to support ever-increasing traffic growth are discussed at the end.

Failures in the GMPLS (Generalized Multi-Protocol Label Switching) control plane and in the data plane may independently occur. The established data plane connections such as lightpaths in WDM networks must remain operational in the event of a control plane failure. A control plane failure should not cause changes of the state of connections and resources in the data plane. In addition, the control plane needs to recover the lost state information, or acquire up-to-date state information. The engineering of GMPLS control plane failure recovery techniques must consider different failure scenarios, co-ordinations of different recovery mechanisms. In this paper, we summarize the graceful restart mechanism for the signalling protocols, then present a two-step failure recovery of the signalling protocols to improve the recover speed.

Feature Issue on Next-Generation WDM Network Design and Routing (WDMN). To address the integration of [IP/MPLS (multiprotocol label-switching)] packet and (optical) transport networks, the Optical Internetworking Forum (OIF) has defined a user-to-network interface (UNI) for overlay networks: the OIF UNI version 1.0, also referred to as the Public UNI. However, since its implementation agreement specification, it has become clear that this UNI--based on OIF-specific extensions to the generalized MPLS (GMPLS) protocols--will not be able to meet the future requirements of some operational environments. Hence a flexible, extensible, and fully GMPLS-compliant UNI is being defined at the Internet Engineering Task Force (IETF): the Private UNI (aka GMPLS for overlay networks). The Private UNI enhances the interaction between the packet and transport network control planes of a multilayer network architecture. This interface is particularly suitable for a control-plane interconnection model in which the equipment belongs to a common administrative entity (i.e., a single carrier environment). Signaling sessions through the Private UNI are used to invoke two main services that require constructive coordination between the network layers: provisioning and network recovery. Here we present the Private UNI specific GMPLS resource reservation protocol-traffic engineering (RSVP-TE) extensions in support of these services in IP/MPLS over SONET/SDH (synchronous optical network/synchronous digital hierarchy) GMPLS multilayer networks and illustrate how Private UNI signaling enhances coordination in multilayer network recovery.

Super-channel (or multi-carrier) transmission is today one of the most promising techniques for the support of high line rates, which are required to satisfy the massive increase of Internet traffic. Moreover, flex-grid optical networks seem to be the candidates for backbone networks by enabling high spectral efficiency thanks to the adoption of the ITUT flex-grid. Such networks may suffer from spectrum fragmentation, which can prevent the establishment of new connections. For this reason, defragmentation techniques (i.e., reoptimization) have been widely studied, especially considering single-carrier transmission. Inparallel, the software defined networking (SDN) paradigm and the active stateful path computation element (PCE) are emerging as candidates for the control of next-generation optical networks. Such architectures are also particularly suitable in the case of defragmentation since they enable the controller to trigger reoptimization procedures. In this paper, we investigate defragmentation in the presence of super-channels, at both the control and data planes. We propose and experimentally demonstrate a technique based on a periodically poled lithium niobate waveguide to achieve both frequency conversion and defragmentation in elastic (or flex-grid) optical networks. Its peculiarity is that it is suitable for super-channels because it avoids detrimental subcarrier overlapping during a frequency shift. SDN with the OpenFlow protocol is discussed for the control of such operations, as well as the active stateful PCE and generalized multi-protocol label switching (GMPLS). The frequency conversion and defragmentation techniques are demonstrated in a lab trial considering a 200 Gb/s super-channel and extended OpenFlow for the control plane. No loss of data is experienced.

New and emerging use cases, such as the interconnection of geographically distributed data centers (DCs), are drawing attention to the requirement for dynamic end-to-end service provisioning, spanning multiple and heterogeneous optical network domains. This heterogeneity is, not only due to the diverse data transmission and switching technologies, but also due to the different options of control plane techniques. In light of this, the problem of heterogeneous control plane interworking needs to be solved, and in particular, the solution must address the specific issues of multi-domain networks, such as limited domain topology visibility, given the scalability and confidentiality constraints. In this article, some of the recent activities regarding the Software-Defined Networking (SDN) orchestration are reviewed to address such a multi-domain control plane interworking problem. Specifically, three different models, including the single SDN controller model, multiple SDN controllers in mesh, and multiple SDN controllers in a hierarchical setting, are presented for the DC interconnection network with multiple SDN/ OpenFlow domains or multiple OpenFlow/ Generalized Multi-Protocol Label Switching (GMPLS) heterogeneous domains. In addition, two concrete implementations of the orchestration architectures are detailed, showing the overall feasibility and procedures of SDN orchestration for the end-to-end service provisioning in multi-domain data center optical networks.

The aviation Internet Protocol (IP) network will be comprised of manned and unmanned aircraft, ground infrastructure, air to ground access network service providers, Air Navigation Service Providers (ANSP), content provider networks, OEM networks, airline and operator networks and devices, and supporting infrastructure (includes PKI, mobility and management etc.). There will be a full range of applications and protocols that will adopt and exploit the aviation IP network. It is key to understand the security and performance characteristics of the aviation IP networks. Many of the applications, services and protocols that could drive deployment of Internet Protocol Suite (IPS) networking in aviation can only be developed if control and management planes of the network will be secure. Yet, to really understand these properties we need studies of the whole aviation IP network's control and management plane interfaces and sub interfaces protection and security, which are difficult to obtain. To date most studies have not been completed in this area, or the analyses have been conducted using unrealistic network mobility models. To address this issue, we present an extensive analysis of an aviation IP network control and management plane's security in the context of mobility generated by both air to ground and ground to ground systems. We combined control plane and management plane data security to address the aviation IP network security issues and explore the security provision mechanisms to protect aviation critical infrastructure. Hence, this analysis and security mechanisms are a more accurate representation of future aviation IP networks, since it reflects the realistic aviation network eco-system. We analyzed the network to identify and characterize the key properties starting from the characteristics of the aircraft movement and dependency on the IP network control and management plane's security framework. We then explored the security issus related to the IPS control and management planes and evaluated how the security issue impact the design space for deployment.