Sukrit Dasgupta

Path-Computation-Element-Based Architecture for Interdomain MPLS/GMPLS Traffic Engineering: Overview and Performance

The Path Computation Element Working Group at the Internet Engineering Task Force is chartered to specify a PCE-based architecture for the path computation of interdomain MPLS- and GMPLS-based traffic engineered label switched paths. In this architecture, path computation does not occur at the head-end LSR, but on another path computation entity that may not be physically located on the head-end LSR. This method is greatly different from the traditional per-domain approach to path computation. This article presents analysis and results that compare performance of the PCE architecture with the current state-of-the-art approach. Detailed simulations are undertaken on varied and realistic scenarios where preliminary results show several performance benefits from the deployment of PCE. To provide a complete overview of significant development taking place in this area, milestones and progress at the IETF PCE WG are also discussed.

Dynamic traffic engineering for mixed traffic on international networks

In this paper, a novel distributed dynamic traffic engineering (Dynamic TE) mechanism is proposed. The mechanism periodically updates bandwidth reservation and selects the optimum path (resizing and rerouting) for each TE-LSP according to its computed traffic load, leading to path reoptimization and better network utilization. Different resizing policies are investigated and their effect on QoS is analyzed. Detailed performance analysis is then undertaken using simulations on conditions similar to an international transit network. A mixed load of voice and data traffic originating in different timezones is used on a realistic network where all the links have an independent probability of failure. The simulation results show significant performance improvement using Dynamic TE for several metrics of interest and give insight into several scenarios that could benefit from its deployment.

Trend Based Bandwidth Provisioning: An Online Approach for Traffic Engineered Tunnels

In this paper, a novel dynamic bandwidth provisioning scheme for traffic engineered tunnels is proposed. The mechanism uses information from the traffic trend to make resizing decisions and is designed to lower signaling and computational overhead while meeting QoS constraints. The traffic trend is observed using a slope estimator and a memory moderator unit. The slope estimator periodically analyzes traffic for growth and spikes whereas the memory moderator keeps track of traffic history and uses it to influence the update in reservation. Key metrics are identified and detailed analysis is then undertaken to gauge the performance of this approach. Accurate simulations on realistic traffic profiles and topologies show effective resizing and reduction in signaling overhead. A comparison with similar state-of-the-art mechanisms is also discussed.

A Performance Study of IP and MPLS Traffic Engineering Techniques Under Traffic Variations

In this paper, a quantitative study of the benefits and shortcomings of IP and MPLS traffic engineering techniques under realistic traffic variation scenarios is presented. While both techniques can achieve similar degree of optimization under steady state conditions, our simulation results show the impact on each when realistic traffic variations are induced in the network. A detailed simulator has been developed to facilitate the study, and several new metrics of interest are analyzed to present a novel point of view.

A New Distributed Dynamic Bandwidth Reservation Mechanism to Improve Resource Utilization: Simulation and Analysis on Real Network and Traffic Scenarios

In this paper, a novel distributed dynamic MPLS traffic engineering (dynamic TE) mechanism is proposed and its performance under failure scenarios and increased traffic load is analyzed when compared to other traditional approaches (static IP and TE). The new mechanism periodically updates bandwidth reservation and selects path (resizing and rerouting) for each TE LSP according to its computed traffic load, which leads to path reoptimization and better network utilization. Dynamic TEs performance is analyzed via simulation using real network and traffic scenarios in a newly created simulator, which was carefully developed to reproduce as accurately as possible the behavior of such networks. The simulation results show the significant performance improvement of dynamic TE for several metrics of interest and give insight into other scenarios that could benefit from its deployment.

CAM05-5: Bandwidth Constraint Models: A Performance Study with Preemption on Link Failures

Bandwidth constraint models have been a topic of intense discussions at the IETF meetings. Three conventional methods have been described in informational IETF RFCs and their performance on a single link has been analyzed and discussed in the literature. In this article, we take a further step into analyzing their performance and optimal bandwidth constraint setting for a real network scenario. A new model is proposed and compared to existing ones when failure events may cause preemption of traffic trunks in a network. Our simulations results provide great insight on the benefits of the methods.

Combined Preemption and Adaptation in Next Generation Multiservice Networks

Preemption and adaptation are two common techniques for controlling inelastic traffic such as streaming media. Adaptation policies dynamically increase or decrease the transmission rate of the stream in response to the presence or absence of network congestion. On the other hand, preemption policies select streams to be removed from the congested route. The removed streams may be rerouted through less favorable paths in the network. Adaptation causes a virtual increase in network capacity at the cost of reducing the client perceived stream quality (since rate reduction is achieved through lossy compression). Preemption permits improved blocking probabilities and traffic alignment on shortest paths for high priority traffic at the expense of performance degradation for low priority traffic. In this paper, we demonstrate the aforementioned performance trade-offs and the increased efficacy of control achievable through the combined use of preemption and adaptation policies.