Dimitrios Katramatos

TeraPaths: End-to-End Network Path QoS Configuration Using Cross-Domain Reservation Negotiation

TeraPaths is a DOE MICS/SciDAC-fundedproject conceived to address the needs of the high energy and nuclear physics scientific community for effectively protecting data flows of various levels of priority through modern high-speed networks. TeraPaths is rapidly evolving from a last-mile, LAN QoS provider to a distributed end-to-end network path QoS negotiator through multiple administrative domains. Developed as a web service-based software system, TeraPaths automates the establishment of network paths with QoS guarantees between end sites by configuring their corresponding LANs and requesting MPLS paths through WANs on behalf of end users. The primary mechanism for the creation of such paths is the negotiation and placement of advance reservations across all involved domains. This paper describes the status of the project, our experiences so far, as well as the directions of our continued work.

End-to-end network QoS via scheduling of flexible resource reservation requests

Modern data-intensive applications move vast amounts of data between multiple locations around the world. To enable predictable and reliable data transfers, next generation networks allow such applications to reserve network resources for exclusive use. In this paper, we solve an important problem (called SMR3) to accommodate multiple and concurrent network reservation requests between a pair of end sites. Given the varying availability of bandwidth within the network, our goal is to accommodate as many reservation requests as possible while minimizing the total time needed to complete the data transfers. First, we prove that SMR3 is an NP-hard problem. Then, we solve it by developing a polynomial-time heuristic called RRA. The RRA algorithm hinges on an efficient mechanism to accommodate large number of requests in an iterative manner. Finally, we show via numerical results that RRA constructs schedules that accommodate significantly larger number of requests compared to other, seemingly efficient, heuristics.

Design and implementation of an intelligent end-to-end network QoS system

End-to-End guaranteed network QoS is a requirement for predictable data transfers between geographically distant end-hosts. Existing QoS systems, however, do not have the capability/intelligence to decide what resources to reserve and which paths to choose when there are multiple and flexible resource reservation requests. In this paper, we design and implement an intelligent system that can guarantee end-to-end network QoS for multiple flexible reservation requests. At the heart of this system is a polynomial time algorithm called resource reservation and path construction (RRPC). The RRPC algorithm schedules multiple flexible end-to-end data transfer requests by jointly optimizing the path construction and bandwidth reservation along these paths. We show that constructing such schedules is NP-hard. We implement our intelligent QoS system, and present the results of deployment on real world production networks (ESnet and Internet2). Our implementation does not require modifications or new software to be deployed on the routers within network.

StorNet: Co-scheduling of end-to-end bandwidth reservation on storage and network systems for high-performance data transfers

Modern scientific data-intensive applications brought about the need for novel data transfer technologies and automated tools capable of effectively utilizing available raw network bandwidth and intelligently assisting scientists in replicating large volumes of data to desired locations in a timely manner. In this paper we describe the design of StorNet, an integrated end-to-end resource provisioning and management system for high performance data transfers that can operate with heterogeneous network protocols and storage systems in a federated computing environment. StorNet allocates and co-schedules storage and network resources involved in data transfers. It is based on existing Storage Resource Manager, TeraPaths, and OSCARS capabilities. StorNet provides data intensive applications with the capability of predictable, yet efficient delivery of data at rates of multiple gigabits/second, bridging end-to-end advanced storage and network technologies in a transparent way.

StorNet: Integrated Dynamic Storage and Network Resource Provisioning and Management for Automated Data Transfers

StorNet is a joint project of Brookhaven National Laboratory (BNL) and Lawrence Berkeley National Laboratory (LBNL) to research, design, and develop an integrated end-to-end resource provisioning and management framework for high-performance data transfers. The StorNet framework leverages heterogeneous network protocols and storage types in a federated computing environment to provide the capability of predictable, efficient delivery of high-bandwidth data transfers for data intensive applications. The framework incorporates functional modules to perform such data transfers through storage and network bandwidth co-scheduling, storage and network resource provisioning, and performance monitoring, and is based on LBNLs BeStMan/SRM, BNLs TeraPaths, and ESNets OSCARS systems.

The TeraPaths Testbed: Exploring End-to-End Network QoS

The TeraPaths project at Brookhaven National Laboratory (BNL) investigates the combination of DiffServ-based LAN QoS with WAN MPLS tunnels in creating end-to-end (host-to-host) virtual paths with bandwidth guarantees. These virtual paths prioritize, protect, and throttle network flows in accordance with site agreements and user requests, and prevent the disruptive effects that conventional network flows can cause in one another. This paper focuses on the TeraPaths testbed, a collection of end-site subnets connected through high-performance WANs, serving the research and software development needs of the TeraPaths project. The testbed is rapidly evolving towards a multiple end-site infrastructure, dedicated to QoS networking research, and it offers unique opportunities for experimentation with minimal or no impact on regular, production networking operations.

Virtual network on demand: dedicating network resources to distributed scientific workflows

The VNOD project aims to build an on-demand network virtualization infrastructure that can deliver the unprecedented networking performance and quality of service required by modern, distributed, data-intensive applications utilized by user communities. Recent networking technologies, already deployed in production and/or in experimental phases, offer the capability to dynamically provision network resources interconnecting multiple end sites hosting storage and computing resources. The VNOD infrastructure described in this paper leverages these technologies to provide an environment that facilitates the establishment and management of virtual network topologies. At the same time, VNOD also offers a platform for co-scheduling end-site resources with local and wide-area network resources through the use of various algorithms and optimization objectives.

Establishment and Management of Virtual End-to-End QoS Paths through Modern Hybrid WANs with TeraPaths

The resource reservation capabilities offered by modern wide area networks, such as ESnet and Internet2, create a new network utilization model that coexists but drastically differs from the standard best-effort network paradigm. These capabilities enable the dedication of network resources to specific users/applications that may suffer from interruptions and other adverse effects because of the default best-effort behavior of networks. Extending the new capabilities through the local area networks of end sites and making them available to end users and applications in a useful, transparent, and scalable manner is a variation of the “last mile” problem. The TeraPaths project at Brookhaven National Laboratory is pioneering a framework that takes advantage of the new capabilities to establish and manage on-demand true end-to-end QoS-aware network paths dedicated to authorized data flows. In this paper, we examine the issues raised by the new end-to-end resource reservation-based networking paradigm and the implications/benefits for end users and applications.

Scheduling end-to-end flexible resource reservation requests for multiple end sites

Wide area research and education networks, such as ESnet and Internet2 in the US and GEANT in Europe, have recently deployed software that makes possible to reserve bandwidth in the form of dynamic circuits. Such circuits offer guaranteed QoS to specific data flows, significantly increasing the reliability and predictability of data transfers. In this paper, we study the problem of constructing routes and scheduling bandwidth reservations for data transfers between multiple pairs of end sites. We develop an algorithm, called RRM, to solve this problem. Our objective is to maximize the number of satisfied data transfer requests while minimizing the total data transfer times. We further prove that our problem is NP-hard and compare our algorithm with a baseline FCFS algorithm through simulations. The simulations indicate that our algorithm accommodates up to 160% more requests and achieves up to 50% shorter average data transfer times than the baseline algorithm.

Software-Defined Network Solutions for Science Scenarios: Performance Testing Framework and Measurements

High-performance scientific workflows utilize supercomputers, scientific instruments, and large storage systems. Their executions require fast setup of a small number of dedicated network connections across the geographically distributed facility sites. We present Software-Defined Network (SDN) solutions consisting of site daemons that use dpctl, Floodlight, ONOS, or OpenDaylight controllers to set up these connections. The development of these SDN solutions could be quite disruptive to the infrastructure, while requiring a close coordination among multiple sites; in addition, the large number of possible controller and device combinations to investigate could make the infrastructure unavailable to regular users for extended periods of time. In response, we develop a Virtual Science Network Environment (VSNE) using virtual machines, Mininet, and custom scripts that support the development, testing, and evaluation of SDN solutions, without the constraints and expenses of multi-site physical infrastructures; furthermore, the chosen solutions can be directly transferred to production deployments. By complementing VSNE with a physical testbed, we conduct targeted performance tests of various SDN solutions to help choose the best candidates. In addition, we propose a switching response method to assess the setup times and throughput performances of different SDN solutions, and present experimental results that show their advantages and limitations.