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www.ait.edu.gr AN OPTICAL NETWORK INFRASTRUCTURE SUITABLE FOR GLOBAL GRID COMPUTING D. Simeonidou, R. Nejabati & M. J. O’Mahony University of Essex Wivenhoe Park, Colchester CO4 3SQ, UK A. Tzanakaki & I. Tomkos Athens Information Technology Center Markopoulou Ave., PO. BOX 68, 190 02 Peania, Athens, Greece Optical Network Infrastructures for Grid Computing www.ait.edu.gr Outline • Global Grid scenario based on optical networks • Appropriate switching paradigm •Optical Burst Switching • The functional blocks required: •Core Router •Edge router functionality •Grid User Network Interface •Grid Resource Network Interface • Challenges and solutions in terms of functionality and technology Optical Network Infrastructures for Grid Computing www.ait.edu.gr Global Computing • Local computational resources cannot keep up with the demands generated by some users/applications: – high-volume (long- or short-lived) jobs with high demands for processing and storage – large number of medium/small jobs requesting distributed resources • Distributed computing using the concept of a global computational Grid is proposed – It is not a new paradigm but until recently networks could not support the features and capabilities to offer efficient use of remote resources Optical Network Infrastructures for Grid Computing www.ait.edu.gr Infrastructures for Grids • The Grid application characteristics and requirements influence the choice of a suitable network infrastructure – transport and switching format – control signalling and management – physical layer technology • Grid applications differ with respect to the following characteristics: – granularity of traffic flows – required data transaction bandwidth – QoS and acceptable delay – throughput and packet loss – storage capacity – processing power etc. Optical Network Infrastructures for Grid Computing www.ait.edu.gr Applications • Particle physics large international collaborations and experiments involve enormous amounts of data requiring processing and analysis of Petabytes per year • Very Long Baseline Interferometry (VLBI) used by radio astronomers for detailed images and experiments bring data from distributed instruments to a central point to correlate the signals from individual telescopes • High Performance Computing and Visualization focuses on adapting and developing parallel codes for execution on parallel processors. Remote visualisation of terabytes of data requiring high bandwidth links ~ 1 Gbit/s or hundreds Mbit/s that increase with the number of remote observers • E-Health, e.g. Mammography introduces increased capacity requirements due to size and quantity of scan images – For 100 patients to be screened remotely, the network would have to carry 1.2GB of data every 30 seconds – For this type of application speed of data transfer is important Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid Features and Characteristics • Suitable network infrastructures are required to offer very different features compared to traditional telecommunications infrastructures • In telecommunications networks when traffic demands arise there is always a predetermined pair of two discrete points that need to communicate • In Grid networks particular end-users/applications require to access available network resources for processing/storage and need to identify their availability – Only the source is predetermined, while the destination has to be discovered and identified using intelligent mechanisms supporting advanced signalling schemes •Self organization • In Grids bidirectionality and symmetry of connections unlike telecommunications networks is not necessary. The two directions are generally required, one to discover and access the network resources and submit the job and the other to extract the results and deliver them to the user – However, the two directions can be decoupled and set-up independently Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid Networks I • The common requirements in this type of networks are summarised as follows: – High capacity for bulk data transfer, low cost bandwidth on demand for short or long periods of time between discrete points across the network (i.e. point and click provisioning) – Service granularity at the wavelength and sub-wavelength level – Multicasting capabilities – Hardware flexibility to support wide range of different distributed resources – Resilience to different layers, from the application layer to the wavelength layer – Network security – Ability to provide management and control of distributed network resources to the user/application Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid Networks II • In these networks resource request, discovery and allocation are performed initially when a processing requirement arises. There is no bandwidth reservation in advance - core routers decide on the fly where to forward the data • Core routers require some application and network-level awareness to configure the resources best suited for the task. This can be achieved utilising two types of information: – The data needs to be accompanied by information on the nature of the job e.g. estimated computational and storage capacity, QoS related information (feed-forward information) – Information about the status of the network needs to be included. The grid resources provide periodically information about their status and availability e.g. free storage capacity, computational load, and network resources (feed-back information) Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Network Infrastructure for Grids I Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Network Infrastructure for Grids II • Distributed computing becomes a realistic solution with the recent advancements of optical networks based on wavelength division multiplexing (WDM) • Can support a distributed control plane to allow control/access and even ownership of network resources by the users/applications in contrast to traditional telecommunications networks • Set-up, control and tear-down of end-to-end lightpaths across multiple domains can be provided through the use of – existing protocols like Generalised Multiprotocol Label Switching (GMPLS) – new protocols such as the Optical Border Gateway Protocol (OBGP) Optical Network Infrastructures for Grid Computing www.ait.edu.gr Switching Paradigm for Grids • Optical burst switching (OBS) supports multi-service traffic, offering high granularity (sub-wavelength), high spectral efficiency as well as bandwidth and low latency • Offers transport for highly demanding Grid applications and all-optical data transmission with ultra-fast user/application-initiated light path setup • Accommodates bursty traffic with improved network economics and provide convergence of electronic and optical technologies • Enables control and management integration and simplification offering a distributed control plane supporting advanced signaling schemes Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Burst Switching • OBS assumes burst aggregation at the edge of the network with burst lengths from 10s of kB to several MB • OBS is based on the asynchronous operation mode with variable length optical bursts depending on the nature of the application • The control information is out of band and transmitted prior to the burst – It is at a lower data-rate than the data burst – It is processed independently of the data burst mostly in the electronic domain – The value of the time offset may be used for offering QoS differentiation •Resulting in reduction or elimination of optical buffering • The data burst is transparently switched and routed through the network without the requirement of any optoelectronic conversion Optical Network Infrastructures for Grid Computing www.ait.edu.gr OBS Network Scenario I Optical Network Infrastructures for Grid Computing www.ait.edu.gr OBS Network Scenario I • OBS can support a set of important requirements for Grid users listed below: • Application initiated lightpath set-up • Resource discovery and allocation mechanisms • Delivery of jobs to the available resources • Delivery of processing results (if there are any) to the user • Dedicated network feedback mechanisms to user • Providing necessary flexibility in architectures to support both carrier -owned and user-owned networks • Supporting the requirements for both physical and application layer QoS • Light-trees & Optical Multicasting • OBS can deal with a wide variety of applications and accommodate small, medium and large jobs to support the application requirements in terms of duration, latency etc • OBS does not require resource reservation and does not impose any strict requirement for symmetry in the two directions of transmission Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Multicasting • Optical multicasting is the concept of 1:N light-trees • A light-tree is a clear channel originating at a given source node having multiple destination nodes i.e. is a point-to-multipoint channel. The use of light-trees can significantly reduce the number of hops (or lightpaths) that the data has to traverse and therefore significantly improve the throughput of the network. • Optical multicasting can be applied in OBS network scenarios for grid applications to improve network performance and efficiency. In general avoiding multicasting at a higher layer: •reduces requirements for optoelectronic conversions •limits the need for store-and-forward functions •enhances the virtual connectivity of the network Optical Network Infrastructures for Grid Computing www.ait.edu.gr Core Routers - Optical Burst Switches Buffering Switching 1 1 . Input . . Output . N input ports . Processing . . . N output ports . . . Processing . N N Electronic Control Routing Table Input processing: power equalisation, activates control Switching: provides path between switch input port and required output port Output processing: optical burst conditioning Buffering: not always required, stores bursts when contention arises Routing table: stores routing information Control: control switch fabric, with info from control packet and routing table Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Burst Switches I • An optical burst switch architecture and the appropriate switching technology should offer advanced features such as • dynamic reconfiguration with high switching speed (~ ms) • strictly non-blocking connectivity between input and output ports • multicasting capabilities • capability to address contention issues and QoS differentiation • scalability • upgradeability • minimum performance degradation for all paths • To resolve contention in the optical burst switch the following options and their combination can be used: • Wavelength dimension: wavelength conversion • Space dimension: deflection routing, in which optical bursts are diverted through a different route to their destination nodes e.g. hot potato scheme • Time dimension: optical or electronic buffering Optical Network Infrastructures for Grid Computing www.ait.edu.gr Optical Burst Switches II • Multicasting operation can be achieved using passive splitters and couplers • Alternative solutions may be also attractive in terms of performance, functionality and scalability such as: • multicasting switches with fast response • wavelength converters supporting multicasting capabilities • other optical/optoelectronic devices and subsystems offering similar features Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid User-Network Interface (GUNI) I The Grid edge device with GUNI functionality is responsible for: • User job pre-processing and transmission entity construction •Job classification, aggregation (grooming) •Optical burst assembly •Flexible bandwidth allocation • Pre-processing the results coming back from Grid resources •Send back results to the users • Anycasting the optical burst to the core nodes •λ-selection for anycast • User authentication and security check, job acceptance or rejection • Grid service billing and accounting • Fault detection, protection and restoration Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid User-Network Interface (GUNI) II Optical Network Infrastructures for Grid Computing www.ait.edu.gr Grid Resource-Network Interface (GRNI) • In GRNI is responsible for: • Pre-processing of the incoming optical bursts • Optical burst segregation • Job submission to local Gird resources • Advertising state of the local resources: • Broadcasting of the available processing/storage capacity to the optical network • Sending back results of a completed job • Optical burst assembly • Bandwidth allocation and light-path setup Optical Network Infrastructures for Grid Computing www.ait.edu.gr Conclusions • A variety of applications and the requirements they imposed on global Grid networks have been discussed • A novel Grid network scenario based on optical infrastructures has been proposed • The solution is based on the optical burst switching paradigm to fulfil the Grid application specific traffic requirements and offer efficient sharing of network resources • The fundamental functional blocks needed are the Core Router, the Grid User Network Interface and the Grid Resource Network Interface • The core router based on optical technologies is able to support routing of the optical bursts on the fly and provide advanced features such as optical multicasting • The optical GUNI is able to support fast and dynamic burst assembly and wavelength allocation per burst • The GRNI provides simple signalling between the local resources and the optical network while it offers a data transport mechanism between Grid resources and the optical network Thank you! email@example.com
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