Ali Shakeri

Traffic allocation strategies in WSS-based dynamic optical networks

Elastic optical networking (EON) is a viable solution to meet future dynamic capacity requirements of Internet service provider and inter-datacenter networks. At the core of EON, wavelength selective switches (WSSs) are applied to individually route optical circuits, while assigning an arbitrary bandwidth to each circuit. Critically, the WSS control scheme and configuration time may delay the creation time of each circuit in the network. In this paper, we first detail the WSS-based optical data-plane implementation of a metropolitan network test-bed. Then, we review a software-defined networking (SDN) application designed to enable dynamic and fast circuit setup. Subsequently, we introduce a WSS logical model that captures the WSS time-sequence and is used to estimate the circuit-setup response time. Then, we present two batch service policies that aim to reduce the circuit-setup response time by bundling multiple WSS reconfiguration steps into a single SDN command. Resulting performance gains are estimated through simulation.

A two-layer network Orchestrator offering trustworthy connectivity to a ROS-industrial application

This paper describes an experiment carried out to demonstrate robustness and trustworthiness of an orchestrated two-layer network test-bed (PROnet). A Robotic Operating System Industrial (ROS-I) distributed application makes use of end-to-end flow services offered by PROnet. The PROnet Orchestrator is used to provision reliable end-to-end Ethernet flows to support the ROS-I application required data exchange. For maximum reliability, the Orchestrator provisions network resource redundancy at both layers, i.e., Ethernet and optical. Experimental results show that the robotic application is not interrupted by a fiber outage.

An SDN-enabled multi-layer protection and restoration mechanism

Abstract Transport networks consist of multiple layers, technologies, and areas of deployment. For example, they combine electronic packet and wavelength circuit switching in a single turnkey solution. Conventional solutions have for the longest time segregated the network management and control schemes of these layers, creating silos of operations. This legacy limits flexibility and programmability of extant solutions. In this paper, we describe PROnet, its SDN orchestrator, and a demonstration of its reliability while supporting an advanced manufacturing application running in decentralized mode. PROnet is a two-layer Research and Education Network (REN) under deployed at and around the UT Dallas campus. Resources in the PROnet Ethernet-over-Wavelength Division Multiplexing (WDM) two-layer architecture are managed by a hierarchical SDN orchestrator, which provides two critical functions: 1) on-demand multi-layer path provisioning and 2) coordinated fault handling at both layers. With the first function, the orchestrator automatically provisions optical circuits to efficiently meet the Ethernet flow fault-tolerant requirement as dictated by the application. With the second function, the orchestrator coordinates response procedures at both layers to overcome a first network outage and prepare the network to handle a potential second outage. We refer to this latter function as Multi-layer Protection (implemented at the Ethernet layer) and Restoration (implemented at the WDM layer) mechanism.

Estimating the effect of Wavelength Selective Switch latency on optical flow switching performance

Optical networks are well suited to support massive data exchanges between data centers. Elephant traffic flows can be routed over provisioned and dedicated lightpaths (optical flows) while other (mice) flows, which are routed by electronic switches, are unaffected. In some solutions, Wavelength-Selective Switches (WSSs) are employed in the optical nodes to individually route the lightpath towards its destination. WSSs take time to be switched and delay the lightpath setup time. In this paper, the authors compare three service policies for WSS devices aiming to reduce the lightpath setup and tear down times. The conventional service policy assumes that each setup (tear down) request is handled individually. Two other service policies assume that groups of setup (tear down) requests are handled together by the WSS. These policies are implemented in a discrete event simulator, which is used to estimate the end-to-end lightpath setup and tear down time across an arbitrary mesh network. Simulation results show that group service policies outperform the conventional policy at high loads. The grouping policies are useful to reduce the lightpath setup time especially in the presence of lightpaths that are frequently set up and have relatively short holding time (short duration of elephant-optical flows).