Cunqian Yu

A new heuristic protection algorithm based on survivable integrated auxiliary graph in waveband switching optical networks

In this paper, we study the survivability in waveband switching optical networks and propose a new heuristic algorithm called Protection based on Survivable Integrated Auxiliary Graph (PSIAG) to tolerate the single-link failure. The survivable integrated auxiliary graph (SIAG) is compared of the single virtual topology layer and multiple waveband-plane layers, and it can well solve the problem of routing and waveband assignment. In PSIAG, we can feasible use the waveband sub-path grouping scheme based on SIAG to save the switching ports in MG-OXCs. For each demand, PSIAG first computes the single-hop or multi-hop route-pair including a primary path and a link-disjoint backup path on virtual topology layer. If the route-pair cannot be found on virtual topology layer, PSIAG then computes the hybrid multi-hop route-pair on jointing the virtual topology layer and waveband-plane layers. Simulation results show that PSIAG can obtain better performance than previous algorithm.

Planning of survivable long-reach passive optical network (LR-PON) against single shared-risk link group (SRLG) failure

Long-Reach Passive Optical Network (LR-PON) is known as a promising and economical solution for Next-Generation PON (NG-PON). Survivability is one of the key issues in the planning of LR-PON because massive high-rate traffic flows may be interrupted in case of network component failure. However, the survivability issue for LR-PON is addressed in little works. More importantly, most of the previous works focus on single distribution fiber failure and remain untouched the simultaneous failure of multiple distribution fibers, which is a possible failure scenario in LR-PON. In this paper, we focus on the survivability of LR-PON against single Shared-Risk Link Group (SRLG) failure. A reliability model is proposed to represent the disconnection probability of the ONUs. Based on this reliability model, we propose a novel Backup Fibers Protection (BFP) scheme. In the BFP scheme, we deal with the optimization problem of allocating backup capacity and deploying backup fibers. Under the constraint of reliability requirement, our objective is to fully protect all traffic demand in the network with the minimum deployment cost of backup fibers. Both ILP-based approach and heuristic approach are proposed to solve the optimization problem in the BFP scheme. To the best of our knowledge, this paper is the first work regarding the survivability of LR-PON against single SRLG failure. Through extensive simulation, we investigate the performance of BFP and demonstrate its effectiveness in different scenarios.

Resource management and control in converged optical data center networks

In addition to the optical interconnection among servers for the Intra Data Center (IDC), the optical interconnection of geographically distributed data centers also becomes increasingly important since data centers are geographically distributed so that one data center maybe far away from another. So the converged Optical and Data Center Network (ODCN) emerges as the times require. In the ODCN, each optically interconnected IDC locates at the edge of the optical backbone. In this article, we first make an extensive survey on the resource management and control in the ODCN, and we find that: (1) for this new network paradigm, the intelligent coexistence of heterogeneous technologies should be considered because the ODCN will be required to satisfy diverse and highly dynamic network services; (2) the integrated virtualization of backbone bandwidth and computing resources should be performed for the resource management in ODCNs, with the objective to improve the underlying infrastructure utilization; (3) after performing the integrated virtualization, a set of virtual networks are generated, and each of them has virtual lightpaths and virtual machines. But a static virtual network merely satisfies a certain range of Service Level Agreements (SLAs), and it merely adapts to a particular network status. When the SLA significantly varies or the Quality of Transmission (QoT) gets worse, it is necessary to trigger the dynamic planning for the virtual network reconfiguration; (4) to decrease the control overhead and the delay of making decisions for the dynamic planning, it is practical to embed a highly effective network control plane into intelligent ODCN. Consequently, we make a blueprint where we execute the intelligent coexistence, integrated virtualization and dynamic planning for the resource management in ODCNs. Some preliminary works and simulation results will guide the future work.

A novel dynamic virtual infrastructure planning for converged optical network and data centers under power outage and evolving recovery

Abstract With advanced Wavelength-Division-Multiplexing (WDM) techniques and cloud computing, incorporating the optical backbone into data centers attains extensive attention. A large-scale electric power outage, which could be caused by major equipment failures or the disaster, makes only part of servers available and significantly degrades the whole infrastructure performance. With limited power recovery resources (e.g., generators), we recovery the power supply progressively over multiple time periods. Under these scenarios, we propose a dynamic Virtual Infrastructure (VI) planning. In order to save link bandwidth and active servers, we integrate traffic grooming with server consolidation to construct virtual networks. In order to reduce the blocking rate, we utilize anycast routing and resource balancing to reconfigure virtual networks. The experimental results have demonstrated the effectiveness of our strategy.

RLDP: A novel risk-level disjoint protection routing algorithm with shared backup resources for survivable backbone optical transport networks

In this paper, we investigate the problem of survivable routing in backbone optical transport networks with Shared-Risk Link Groups (SRLG) constraints. We present a new idea that considers the different risk-level protection for difference service level requirements of connection requests. Based on the presented idea, we propose an effective Risk-Level Disjoint Protection (RLDP) routing algorithm for provide different service level for connection requests. In RLDP, the backup path can be partial SRLG-disjoint with the primary path, and the backup wavelengths also can be shared by different backup paths if their corresponding primary paths are risk-level disjoint. Compared with the conventional SRLG-Disjoint Protection (SDP) routing algorithm that provide full SRLG-disjoint survivable routing for each connection request, RLDP can perform better resource utilization ratio and blocking probability. Simulation results are shown to be promising.

Adaptive multilevel modulation for grooming in elastic cloud optical networks

In order to mitigate the mismatch of granularities between fixed grid and client traffic, the elastic optical network (EON) was proposed by using orthogonal frequency division multiplexing. In EONs, the bandwidth variable transponder adjusts the number of bits per symbol, so that an optical signal generates by using just enough sub-carriers each with appropriate modulation level. Owing to the advantage of line-rate adaption above, the application of cloud computing has witnessed rapid growth in EONs. However, bandwidth variable transponders consume more power compared with ordinary ones, which will lead to a power-thirsty EON if no effective measure is taken. As a result, the green grooming was proposed for EONs. Unfortunately, the adaptive multilevel modulation was neglected in the current works focusing on green grooming. Thus, in this paper, we design a novel modulation adaptive grooming with guaranteeing transmission performances in green EONs. The distance-adaptive spectrum resource allocation is applied to the green grooming algorithm previously designed by us for EONs. The simulation results show that the adaptive multilevel modulation plays an important role on saving spectrum and power consumption for the green grooming in EONs, because the spectral bandwidth can be saved by increasing the number of bits per symbol to transmit the same data rate.

Virtual concatenation-based elastic network embedding for inter-cloud-data-center networks

The elastic optical network (EON) provides fine-grained and orthogonal spectrum slots for the establishment of the elastic connection using orthogonal frequency division multiplexing (OFDM). Currently, the EON interconnection has realized the high-rate transmission among data centers (DCs). With the implementation of cloud DCs (CDCs) and EON virtualization, it becomes very essential to achieve the elastic network embedding (ENE) that facilitates the resource sharing in inter-cloud-data-center networks. The ENE operation consists of two components, the virtual-node mapping from virtual machine to CDC and the virtual-link (VL) mapping from virtual lightpath to fiber link(s). Thus an ENE request can be satisfied only when those two mapping processes have completed successfully. But during the VL mapping, some rigid constraints must be satisfied, such as the spectrum continuity, etc. This makes the ENE operation create the spectrum fragments over fiber links, which results in the denial of requests. Thus in this paper, we take the virtual concatenation (VC) into account when the VL mapping fails. The problem is formulated using the relaxed integer linear programming (ILP) model, and we also design a VC-based heuristic. Simulation results have verified the superiorities of the VC scheme on increasing the spectrum utilization and reducing the blocking rate of ENE requests.

Enhanced Hamiltonian Cycle Protection Algorithm in Survivable Networks

This paper studies the protection with Hamiltonian Cycle in mesh survivable backbone networks, and proposes a new heuristic routing algorithm called Enhanced Hamiltonian Cycle Protection (EHCP) to tolerate single failure. Simulation results show that, compared with conventional HCP algorithm, EHCP can obtain significant improvement in resource utilization ratio.

Protection Routing Algorithm Based on Survivable Integrated Auxiliary Graph in Waveband Switching Optical Networks

In this paper, we propose a new heuristic algorithm, protection based on survivable integrated auxiliary graph (PSIAG), to tolerate the single-link failure in waveband switching optical networks. The survivable integrated auxiliary graph (SIAG) contains single virtual topology layer and multiple waveband-plane layers, and it can well solve the routing and waveband assignment. In PSIAG, we can well use the waveband sub-path grouping scheme based on SIAG to save the switching ports. Simulation results show that PSIAG performs better than previous algorithm.

Survivable Routing with Risk-Level Disjoint in WDM Optical Networks

This paper investigates the survivable routing in backbone optical transport networks with shared-risk link groups (SRLG) constraints, and proposes a new risk-level disjoint protection (RLDP) algorithm for provide different service level for different connection request. Compared with the conventional SRLG- disjoint protection (SDP) algorithm, RLDP performs better resource utilization and blocking probability. Simulation results are shown to be promising.