Marwan Batayneh

On routing and transmission-range determination of multi-bit-rate signals over mixed-line-rate WDM optical networks for carrier ethernet

Ethernets success in local area networks (LANs) is fueling the efforts to extend its reach to cover metro and long-haul networks. This new Ethernet is refereed to as Carrier Ethernet. Among the various transport infrastructures for realizing Carrier Ethernet, wavelength-division multiplexing (WDM) optical network is a strong candidate for this purpose. Optical transmission rates per channel are increasing from 10 to 40 Gb/s and even 100 Gb/s, and they can also coexist in the same fiber. Along with the flexibility associated with such a network with mixed-line rates (MLR), signal-related constraints at high rates become a challenge for cost-efficient routing. Among these issues is the maximum nonregenerated optical distance that a signal can travel before its quality degrades or maximum transmission range (TR). TR is rate-dependent: The higher the rate, the shorter the range. While high-rate pipes may require signal regeneration to restore the signals quality, they support more traffic and, hence, can save resources. We study the problem of cost-efficient routing of multi-bit-rate (1/10/40/100 Gb/s) Ethernet tunnels using MLR over a carriers WDM optical network with signal-transmission-range constraints. We studied the effect of TR for mixed-rate signals (10/40/100 Gb/s) on the networks cost to determine the optimal TR of each bit rate. We present an analytical model based on a mixed-integer linear program (MILP) to determine the optimal TR of a small network. Since MILP has scalability constraints that makes it hard or sometimes impossible to solve for real network topologies, we propose a graph-based solution that constructs a mixed-line-rate auxiliary (MLR-AUX) graph to capture the networks heterogeneity and a weight-assignment approach that allows the routing to be cost-efficient. Our algorithms were tested on a U.S. nationwide network topology. We found that it is possible to reduce the networks cost by using short TR and that the optimal TR depends strongly on traffic characteristics and on the TR values of different bit-rate signals.

Provisioning of deadline-driven requests with flexible transmission rates in WDM mesh networks

With the increasing diversity of applications supported over optical networks, new service guarantees must be offered to network customers. Among the emerging data-intensive applications are those which require their data to be transferred before a predefined deadline. We call these deadline-driven requests (DDRs). In such applications, data-transfer finish time (which must be accomplished before the deadline) is the key service guarantee that the customer wants. In fact, the amount of bandwidth allocated to transfer a request is not a concern for the customer as long as its service deadline is met. Hence, the service provider can choose the bandwidth (transmission rate) to provision the request. In this case, even though DDRs impose a deadline constraint, they provide scheduling flexibility for the service provider since it can choose the transmission rate while achieving two objectives: 1) satisfying the guaranteed deadline; and 2) optimizing the networks resource utilization. We investigate the problem of provisioning DDRs with flexible transmission rates in wavelength-division multiplexing (WDM) mesh networks, although this approach is generalizable to other networks also. We investigate several (fixed and adaptive to network state) bandwidth-allocation policies and study the benefit of allowing dynamic bandwidth adjustment, which is found to generally improve network performance. We show that the performance of the bandwidth-allocation algorithms depends on the DDR traffic distribution and on the node architecture and its parameters. In addition, we develop a mathematical formulation for our problem as a mixed integer linear program (MILP), which allows choosing flexible transmission rates and provides a lower bound for our provisioning algorithms.

Deadline-Driven Bandwidth Allocation with Flexible Transmission Rates in WDM Networks

We investigate dynamic bandwidth allocation with flexible transmission rates for deadline-driven requests (DDRs) in wavelength-division multiplexing (WDM) mesh networks. DDRs provide more scheduling flexibility to the network operator compared with typical requests with no deadline and requiring a fixed bandwidth. By choosing the bandwidth and adapting the transmission rate depending on network state, the networks performance can be improved. We investigate several bandwidth allocation policies and study their benefits on network performance. Our investigation shows that an adaptive policy generally performs the best. Further improvement can be achieved by using dynamic readjustment of the allocated bandwidth.

Interference-aware routing for multi-hop Wireless Mesh Networks

Interference is a major factor that limits the performance of wireless networks. In this work, we present a practical IEEE-802.11-based routing model that captures the dynamic effects of interference in Wireless Mesh Networks (WMN). This is achieved by accurately modeling wireless link capacities in the presence of any number of interferers in a WMN. Our goal is to maximize the network throughput by routing the traffic of all source-destination pairs over the best possible set of routes. We study our methods on two sample networks: a grid WMN and a practical WMN (the Kemper Hall wireless network). In each example, we compare the performance of the proposed routing model with the standard Open Shortest Path First (OSPF), a popular routing protocol. The aggregate network throughput achieved by our model is significantly higher than that achieved by OSPF.

Provisioning of Deadline-Driven Requests with Flexible Transmission Rates in Different WDM Network Architectures

We investigate the problem of provisioning deadline-driven requests with flexible transmission rates in WDM mesh networks. We analyze the networks performance and cost for different node architectures and for different traffic distributions.

SLA-Aware Provisioning for Revenue Maximization in Telecom Mesh Networks

Service level agreement (SLA) is a contract between the service provider (SP) and the customer. Among various parameters, SLA imposes penalties on the SP when the customers quality-of-service (QoS) requirements are violated. Hence, it is desirable to avoid SLA violations and such penalties. SLA also states the maximum amount of downtime a connection may tolerate during its lifetime. In this study, we present a dynamic provisioning scheme called Preemption-Oriented SLA-Aware Provisioning (POSAP) for telecom mesh networks, which considers a connections (1) availability requirements, (2) penalty, and (3) state. In addition to the connections various parameters (availability, penalty, etc.), the amount of affordable downtime is used as a metric to determine the risk of violating the connections SLA, and hence, its priority. Connections priority is denoted by urgency level. Our scheme allows resource preemption among connections, i.e., high-priority connections may preempt backup resources from low-priority connections. Also, new connection requests may preempt resources from existing connections. Urgency level determines how resources can be preempted. Our scheme is applied to a US-wide network. Our results show the improved performance in terms of (1) reduced SLA violations, (2) increased network utilization, and (3) increased network revenue, compared to a dedicated primary-backup (P-B) scheme.

Reliable Multi-Bit-Rate VPN Provisioning for Multipoint Carrier-Grade Ethernet Services Over Mixed-Line-Rate WDM Optical Networks

Ethernets success in local-area networks (LANs) is fueling the efforts to extend its reach to cover metro and long-haul networks. A key enabler for using Ethernet in the carriers network is its ability to efficiently sup port multipoint-to-multipoint (MP2MP) services. MP2MP service is the core underlying structure to enable standard Ethernet services such as Ethernet virtual private networks (E-VPNs). Since most of the research, standardization, and development have focused on designing protection architectures for point-to-point (P2P) Ethernet connections, protecting E-VPN services is an important research problem. Among the various transport methods for realizing carrier Ethernet, the wavelength-division multiplexing (WDM) optical network is a strong candidate. Wavelength channel rates are increasing from 10 to 40 Gbits/s and even 100 Gbits/s, and they can also coexist in the same fiber. We study the problem of cost-efficient provisioning of multi-bit-rate (1/10/40/100 Gbits/s) self-protected E-VPN demands over a carrier-grade Ethernet network employing WDM optical network (Ethernet over WDM) with mixed line rates (MLRs). We study two algorithms for self-protected E-VPN provisioning. The first algorithm reforms the original E-VPN topology and increases the provisioning rates (10/40/100 Gbits/s) of the E-VPN edge demands to create excess capacity that can be used for protection (E-VPN reformation). The second algorithm routes the E-VPN edge demands using the lowest available rate (10/40/100 Gbits/s) and establishes backup capacity for protecting the E-VPN (no E-VPN reformation). Our algorithms are tested on a 17-node German national network topology. The results show that using E-VPN reformation achieves significant cost reduction and significant improvement in the networks performance by reducing the traffic-blocking ratio.

Event-Triggered Reprovisioning with Resource Preemption in WDM Mesh Networks: A Traffic Engineering Approach

We propose a novel scheme for dynamic connection reprovisioning with resource preemption. Study cases show that SLA violations are minimized, particularly for connections with high SLA requirements under heavy network load.

Cost-Efficient Routing in Mixed-Line-Rate (MLR) Optical Networks for Carrier-Grade Ethernet

We study cost-efficient routing in a MLR WDM network for carrier-grade Ethernet. We also study the benefits of a MLR network compared with a single-line rate (SLR) network.

Link-Rate Assignment in a WDM Optical Mesh Network with Differential Link Capacities: A Network-Engineering Approach

Wavelength-division multiplexing (WDM) optical networks are characterized by maturity, high-capacity, agility, flexibility, and cost-efficiency. Today, optical transmission rates are increasing from 10 Gbit/s to 100 Gbit/s which increases the networks flexibility for capacity provisioning. We study the problem of dimensioning optical WDM networks under traffic growth. Particularly, we study link-rate assignment and capacity expansion (namely network engineering). Our study shows that, with careful link-rate assignment, the networks traffic can be satisfied and any traffic growth can be accommodated using the networks current resources with some additional resources so that cost is minimized. Our study also shows that, by careful selection, only a few links with high rates can meet the capacity needs of the network and that any additional high-rate links (extra cost) may not significantly improve the networks efficiency.