Bingbing Li

Efficient routing and spectrum allocation considering QoT in elastic optical networks

In recent years, OFDM-based elastic optical network (EON) has drawn a lot of attention in both academia and industry. Compared to traditional optical wavelength division multiplexing (WDM) network, EON is capable of supporting variable data rate, accommodating traffic demands flexibly, and utilizing spectrum more efficiently. Accordingly, the resource management in EON is different from that in WDM networks and addresses new challenges in network design and control. In this paper, we study the routing and spectrum allocation (RSA) problem in EON. We propose an efficient link-based mixed integer linear programming (MILP) model with the objective to optimally utilize the spectrum resources while considering the Quality of Transmission (QoT). Then the performance of the proposed model is examined through a case study.

Efficient Mixed Topology Configuration Algorithm for Optical Carrier Ethernet

Carrier Ethernet, which extend The algorithm based on constructing the mixed topology and performing link stretching, MT/s, has been proposed for designing cost-efficient Carrier Ethernet in optical network with multi-line-rate. However, the MT/s algorithm has high blocking ratio because the wavelength capacity is fully allocated without considering the load balance of network. In this paper, we propose an efficient mixed topology configuration (EMTC) algorithm by modifying MT/s algorithm. In order to reduce blocking ratio, we adapt a threshold for each link to restrict the link utilization so that traffic load can be distributed over whole network. We also apply the EMTC algorithm into optical hybrid switched network to evaluate the availability of our algorithm for different applications. The performance of the EMTC algorithm is compared with that of MT/s algorithm through OPNET simulation. The simulation results show that our algorithm achieve lower blocking ratio than the MT/s algorithm. Moreover, in hybrid switched network, our algorithm performs better than MT/s algorithm in terms of packet loss ratio and end-to-end delay.

Novel Queue-Grouping Based Round-Robin Protocols for Reducing Collision of OBS Ring Networks

OBS ring networks inherently suffer from the resource contention due to the limited network resources and the one-way reservation. Multiple tokens with the help of control information table (CIT) have been applied to avoid the source and wavelength collision. However, the receiver collision cannot be completely avoided as tokens are processed in a distributed manner. In Round-Robin (RR) queue selection protocol, several bursts destined to the same node may be selected by different tokens simultaneously, resulting in receiver collision. Two novel medium access control (MAC) protocols, called Queue-Grouping based RR (QGRR) and Prior queue-Grouping based RR (PGRR), by scheduling RR manner within special queue groups are proposed to reduce the receiver collision. By further grouping the RR queues according to each wavelength, the probability for different bursts destined to the same node on different wavelengths overlapping in time is significantly reduced. Finally, the proposed protocols are evaluated and compared through OPNET simulator.

Efficient Logical Topology Design Considering Multiperiod Traffic in IP-over-WDM Networks

In recent years energy consumption has become a main concern for network development, due to the exponential increase of network traffic. Potential energy savings can be obtained from a load-adaptive scheme, in which a day can be divided into multiple time periods according to the variation of daily traffic patterns. The energy consumption of the network can be reduced by selectively turning off network components during the time periods with light traffic. However, the time segmentation of daily traffic patterns affects the energy savings when designing multiperiod logical topology in optical wavelength routed networks. In addition, turning network components on or off may increase the overhead of logical topology reconfiguration (LTR). In this paper, we propose two mixed integer linear programming (MILP) models to design the optimal logical topology for multiple periods in IP-over-WDM networks. First, we formulate the time-segmentation problem as an MILP model to optimally determine the boundaries for each period, with the objective to minimize total network energy consumption. Second, another MILP formulation is proposed to minimize both the overall power consumption (PC) and the reconfiguration overhead (RO). The proposed models are evaluated and compared to conventional schemes, in view of PC and RO, through case studies.

Energy and cost efficient logical topology in optical mixed-line-rate networks

With the continuous growth of traffic for years, both the monetary cost and the power consumption of the Internet increase sharply at the same time. Especially, backbone networks will become the main contributor of the overall Internet cost and power consumption. Except the feature of huge total amount, the traffic in future backbone networks will also show high heterogeneity in bandwidth requirement. Based on the variety of those traffic demands, the mixed-line-rate (MLR) schemes have been proposed in recent years. The MLR schemes are considered to b e able to support flexibility for network provisioning. To utilize resources in MLR backbone networks efficiently, logical topology design is an important issue. However, previous studies about logical topology design have focused on optimizing either monetary cost or power consumption of the whole network. In this paper, we design logical topology for optical MLR backbone networks by considering both energy efficiency and cost efficiency. The network cost is defined as an integrity consisting of the monetary cost and the power consumption of the whole network. Then, a Mixed Integer Linear Programming (MILP) formulation is presented to minimize the network cost. In order to evaluate the proposed formulation, it is applied on illustrative case studies. Finally, the numerical results are analyzed and discussed.

Energy Efficient Spectrum Allocation in IP-over-EON with Traffic Grooming

Elastic optical network (EON) based on flexible grid and optical orthogonal frequency division modulation (OFDM) has emerged as an innovative approach to meet the ever-increasing demand. In EON, traffic grooming can improve the efficiency of spectrum by removing the guard band between two adjacent channels. Although network spectrum resource can be utilized more efficiently by traffic grooming, the operation leads to considerable power consumption due to the high data rate of transponder and electronic processing overhead at intermediate nodes. In this paper, we investigate the power consumption of IP-over-EON with traffic grooming. An efficient mixed integer linear programming (MILP) model is proposed to solve the spectrum allocation problem with the objective to minimize network power consumption in IP-over-EON with traffic grooming. The performance of the proposed model is evaluated in terms of spectrum allocation and energy consumption through a case study.

Multi-period logical topology design for IP-over-WDM network with mixed line rates

Improving network energy efficiency has been a challenging issue for the development of networks. Considering the pattern and variation of network traffic, some network components can be turned off during the periods with light load to save energy. However, turning off/on network devices adapting to traffic load may result in the reconfiguration of logical topology in optical wavelength routed networks. On the other hand, the traffic in future network is expected to show high heterogeneity on bandwidth requirement. With flexibility on network provisioning, Mixed Line Rate (MLR) scheme is proposed as a promising candidate to support heterogeneous traffic demand. In this paper, we study the logical topology design of IP-over-WDM network with mixed line rates. We formulate the multi-period logical topology design problem as a mixed integer linear programming (MILP) model with the objective to minimize the overall network power consumption and the reconfiguration overhead between consecutive time periods. Then the proposed model is evaluated and compared with conventional schemes.

Logical Topology Design with Low Power Consumption and Reconfiguration Overhead in IP-over-WDM Networks

Reducing the power consumption of networks has drawn a lot of attention in recent years. To improve the energy efficiency, selectively turning off network components during light traffic periods could be an effective method. However, turning off/on network devices adapting to traffic load may result in the reconfiguration of logical topology in optical wavelength routed networks. In this paper, we study the logical topology design problem under multi-period traffic load in IP-over-WDM networks. To solve the problem, a mixed integer linear programming (MILP) model is proposed with the objective to minimize the overall network power consumption and the reconfiguration overhead between consecutive time periods. The proposed model is evaluated and compared with conventional schemes in terms of power consumption and reconfiguration overhead through a case study.