This paper provides a detailed analysis and modelling of the Operational Expenditures (OPEX) for a network provider. The traditional operational processes are elaborated and the expected changes when using a control plane such as ASON/GMPLS are described. Control planes are promoted as a major technology for the automation of network operations. It is often claimed to allow the reduction of OPEX. However, detailed analysis and quantitative evaluation of the changes induced by such technologies is rare. In this paper we quantify the cost reduction potential of an ASON/GMPLS based control plane. Additionally, we show an important impact of the used resilience scheme on the expenses directly related to continuous costs of infrastructure (floorspace, energy,...) and on the planning and reparation costs. Concerning the service provisioning costs, we show that the introduction of a control plane leads to a reduction in
the order of 50% of the OPEX cost compared to the traditional case.
This paper studies the gradual migration from a link-by-link grooming network without OXCs towards OXC introduction in some nodes, using end-to-end grooming. A migration path introducing OXCs in so-called end-to-end grooming islands is proposed.
This paper deals with resilience in all-optical networks. The main disadvantage when designing all-optical label swapping networks is the enormous dimensions an all-optical node can have. The node's size relates directly to the number of Label Switched Paths passing through the node. In this paper, we discuss how the dimensions of the all-optical node alter when introducing resilience in label swapping and stripping networks. We compare the node dimensions for different recovery strategies and different all-optical networking approaches.
Due to a continuous stream of technological advances, enormous amounts of traffic are aggregated onto a single fiber. The main drive for this is the cost savings that are realized due to the economy of scale. However, a major drawback is the impact of a single failure (e.g., cable cut), which can become very and even unacceptably large. This paper aims at discussing the different techniques that can be applied to deal with such circumstances.
Next generation automatic switched optical networks (ASON) show great promise in coping with increasing bandwidth demands, as they provide both on-demand bandwidth and improved switching flexibility. In a multi-layer data-centric network, such an ASON acts as a server layer and provides the topology for a client IP network. Multi-layer Traffic Engineering (MTE) enhances single-layer traffic engineering (i.e. adaptive routing) with the possibility to reconfigure the logical IP topology, utilizing the aforementioned optical flexibility in setting up and tearing down end-to-end lightpaths. To provide a robust network service, the multi-layer networks must be recoverable from different types of failures. Resilience mechanisms such as various forms of protection and restoration allow to recover from optical layer failures. In a multi-layer network however, some traffic will be forwarded through the IP layer routers, requiring a survivability scheme in this IP layer. This paper shows how MTE strategies that normally cope with changing traffic demands, can be used to provide this IP layer resilience. This is done through diverting affected IP traffic and replacing failing optical lightpaths, effectively leading to a dynamic restoration scheme. We will evaluate and compare failure performance of different types of resilience mechanisms, based on an existing MTE strategy.
Packet switched based network architectures exhibit a high degree of resource sharing and consequently make very efficient use of the available bandwidth. On the other hand, they experience a great amount of transit traffic in IP routers, increasing costs. Wavelength switched based concepts can reduce this transit traffic, but have limited resource sharing and consequently need more resources (wavelengths) to avoid losses. We present a new hybrid network architecture, Overspill Routing In Optical Networks (ORION), which combines the benefits of wavelength switched networks and packet switched networks. An example node hardware design and corresponding control architecture is presented. A case study quantifying the benefits of ORION when compared to three other network architectures is also discussed.
As more and more traffic is transported over communication networks, network survivability becomes a key issue in network design and planning. In this paper first the need for deploying network recovery techniques at multiple layers is motivated. Then the efficient coordination of these network recovery techniques is studied. Not only static but also dynamic multi-layer survivability strategies are presented and studied in this paper: dynamic multi-layer survivability strategies benefit from the ability of the underlying transport network to provide switched connection services in order to allow reconfiguring the logical network at the time of a failure. As not only the traffic volume keeps growing, but also more and more services with distinct reliability requirements are deployed, the benefit of differentiating the multi-layer survivability strategy per traffic class is investigated in this paper. Whereas the case studies in this paper focus on the cost-efficiency of the presented strategies and techniques, also a broader theoretic discussion is given on these techniques.
Although the Optical Transport Network, based on technologies such as Wavelength Division Multiplexing and Optical Cross-Connects, offers tremendous transportation capacity, its management requires frequent manual intervention. However, as the traffic pattern offered to today's transport networks is subject to continuous changes due to the Internet traffic dominance, an optical transport network with a smart, automatic and real-time control system, denoted as Intelligent Optical Network (ION) or Automatic Switched Optical Network (ASON), is desired by network operators. Duly and correctly retrieving the changing traffic load information is a very important factor for the successful deployment of an ION. In this paper, we discuss the influence of the observation window size used for collecting the traffic load information, on the performance of an ION. By comparing the performance of an ION using different traffic observation window sizes, we show that a smaller observation window harms the network stability; while a too large observation window worsens the network reliability. We demonstrate that a suitable traffic observation window size improves the offered Quality of Service (QoS) by reconfiguring the logical layer network at the right time and in the right way.