End-to-end shared restoration in multi-domain networks / by Zhiying Gao.

Emerging multi-service data applications require high-bandwidth high-quality connectivity across multiple network domains, each of which is generally controlled by an independent service provider. These applications necessitate the need for highly intelligent survivable routing mechanisms to compute end-to-end paths and to perform functions of protection and bandwidth management across multiple domains. On the other hand, current protection and restoration mechanisms focus on the network survivability inside a single domain network. Powerful dynamic protection and restoration algorithms have been developed for single-domain networks. The majority of these algorithms are based on the exchange of detailed link-state information among the nodes, which makes them less attractive to networks with multiple domains where link-state information needs to be abstracted within each domain for efficiency and scalability reasons. To address this problem, we present two network information abstraction models designed to aggregate link-state information within each domain and only to advertise the aggregated information to other domains. The first abstraction model is referred to as virtual path abstraction model, with which every domain is abstracted as a set of border-nodes interconnected by virtual paths. The multi-domain network is then topologically aggregated to become a single-domain network, called virtual path network, which consists of border-nodes interconnected internally by virtual paths and externally by inter-domain links. The second abstraction model is referred to as virtual node model, with which every domain is modeled as a virtual node with a certain internal minimum capacity that can be advertised to other domains. The multi-domain network is then topologically aggregated to become a single-domain network, called virtual node network, consisting of virtual nodes interconnected by inter-domain links. We have designed and developed three distributed end-to-end shared restoration schemes based on the information abstraction models presented above. These three schemes are referred to as Link Disjointed Virtual Path (LDVP) restoration. Domain Disjointed Virtual Path (DDVP) restoration, and Link Disjointed Virtual Node (LDVN) restoration. The LDVP and LDVN schemes are designed to provide link diversity between the primary and backup paths of each demand, whereas the DDVP scheme is designed to compute a pair of domain-disjointed paths for the demand. We show that the proposed schemes are more scalable than the existing restoration schemes because they require less amount of link-state information to be advertised between the domains. This will reduce the routing message overhead and make the proposed schemes to be scalable to large multi-domain networks. We also evaluate the performance o f the proposed schemes in terms of capacity usage and restoration time through simulation experiments on two multi-domain networks; one is based on the NSF (National Science Foundation) network, and the other is based on the European Optical Network. The simulation results show that the proposed schemes save the backup bandwidth significantly because of the sharing of backup resources among failure-disjointed connections. The simulation results also show that the restoration time achieved by the proposed restoration schemes (over the multi-domain network) is around or less than 60 ms, which is within the range accepted in today’s networks

Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

A survey on OFDM-based elastic core optical networking

Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed

A Survey on the Path Computation Element (PCE) Architecture

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits

Access and metro network convergence for flexible end-to-end network design

This paper reports on the architectural, protocol, physical layer, and integrated testbed demonstrations carried out by the DISCUS FP7 consortium in the area of access - metro network convergence. Our architecture modeling results show the vast potential for cost and power savings that node consolidation can bring. The architecture, however, also recognizes the limits of long-reach transmission for low-latency 5G services and proposes ways to address such shortcomings in future projects. The testbed results, which have been conducted end-to-end, across access - metro and core, and have targeted all the layers of the network from the application down to the physical layer, show the practical feasibility of the concepts proposed in the project

Dynamic Virtual Network Restoration with Optimal Standby Virtual Router Selection

Title form PDF of title page, viewed on September 4, 2015Dissertation advisor: Deep MedhiVitaIncludes bibliographic references (pages 141-157)Thesis (Ph.D.)--School of Computing and Engineering and Department of Mathematics and Statistics. University of Missouri--Kansas City, 2015Network virtualization technologies allow service providers to request partitioned, QoS guaranteed and fault-tolerant virtual networks provisioned by the substrate network provider (i.e., physical infrastructure provider). A virtualized networking environment (VNE) has common features such as partition, flexibility, etc., but fault-tolerance requires additional efforts to provide survivability against failures on either virtual networks or the substrate network. Two common survivability paradigms are protection (proactive) and restoration (reactive). In the protection scheme, the substrate network provider (SNP) allocates redundant resources (e.g., nodes, paths, bandwidths, etc) to protect against potential failures in the VNE. In the restoration scheme, the SNP dynamically allocates resources to restore the networks, and it usually occurs after the failure is detected. In this dissertation, we design a restoration scheme that can be dynamically implemented in a centralized manner by an SNP to achieve survivability against node failures in the VNE. The proposed restoration scheme is designed to be integrated with a protection scheme, where the SNP allocates spare virtual routers (VRs) as standbys for the virtual networks (VN) and they are ready to serve in the restoration scheme after a node failure has been identified. These standby virtual routers (S-VR) are reserved as a sharedbackup for any single node failure, and during the restoration procedure, one of the S-VR will be selected to replace the failed VR. In this work, we present an optimal S-VR selection approach to simultaneously restore multiple VNs affected by failed VRs, where these VRs may be affected by failures within themselves or at their substrate host (i.e., power outage, hardware failures, maintenance, etc.). Furthermore, the restoration scheme is embedded into a dynamic reconfiguration scheme (DRS), so that the affected VNs can be dynamically restored by a centralized virtual network manager (VNM). We first introduce a dynamic reconfiguration scheme (DRS) against node failures in a VNE, and then present an experimental study by implementing this DRS over a realistic VNE using GpENI testbed. For this experimental study, we ran the DRS to restore one VN with a single-VR failure, and the results showed that with a proper S-VR selection, the performance of the affected VN could be well restored. Next, we proposed an Mixed-Integer Linear Programming (MILP) model with dual–goals to optimally select S-VRs to restore all VNs affected by VR failures while load balancing. We also present a heuristic algorithm based on the model. By considering a number of factors, we present numerical studies to show how the optimal selection is affected. The results show that the proposed heuristic’s performance is close to the optimization model when there were sufficient standby virtual routers for each virtual network and the substrate nodes have the capability to support multiple standby virtual routers to be in service simultaneously. Finally, we present the design of a software-defined resilient VNE with the optimal S-VR selection model, and discuss a prototype implementation on the GENI testbed.Introduction -- Literature survey -- Dynamic reconfiguration scheme in a VNE -- An experimental study on GpENI-VNI -- Optimal standby virtual router selection model -- Prototype design and implementation on GENI -- Conclusion and future work -- Appendix A. Resource Specification (RSpec) in GENI -- Appendix B. Optimal S-VR Selection Model in AMP