Anycast Routing in Optical Burst Switched Grid Networks Marc De Leenheer (1), Farid Farahmand (2), Pieter Thysebaert (1), Bruno Volckaert (1), Filip De Turck (1), Bart Dhoedt (1), Piet Demeester (1), Jason Jue (2) 1 : Dept. of Information Technology, Ghent University, St-Pietersnieuwstraat 41, 9000 Gent, Belgium, marc.deleenheer@intec.ugent.be 2 : Erik Jonsson School of Engineering and Computer Science The University of Texas at Dallas, ffarid@utdallas.edu Abstract To deliver virtually unlimited computing power to residential users, an anycast routed Optical Burst Switched Grid infrastructure is proposed. This architecture is evaluated and compared with traditional shortest path routed systems in Optical Circuit Switched and Burst Switched networks. Introduction Grid computing provides a uniform interface to heterogeneous and geographically distributed resources, all connected over a high speed network. Current Grid implementations are geared toward scientific projects which require large amounts of compute, storage and network resources. These operations remain fairly static over time and as such demand long-lived, photonic network connections. The Optical Circuit Switching (OCS) technique is particularly well suited for this scenario, especially considering the relatively few number of participating sites in these projects. In contrast, opening Grid technology to the consumer market requires support for a large amount of users with dynamic traffic patterns and short-lived connections. It is well known that when the hold times of network connections decrease, OCS shows reduced efficiency because of its inability to reserve bandwidth below the wavelength scale. Optical Burst Switching (OBS) [1] is an emerging technique capable of addressing bandwidth at the sub-lambda level. Already, a working group in the Global Grid Forum (GGF) is committed to the standardization of OBS in the context of Grid computing [2]. Regardless of the employed switching technique, most networks use fixed shortest path routing between endpoints. The goal is to minimize end-to- end delay, but it can cause overloaded links and thus lead to network congestion. To overcome this problem, deflection routing and multi-path routing can be supported. In the consumer Grid scenario [3,4], the user is only interested in his job being processed within certain predetermined requirements. In general, there will exist multiple locations where a job can be executed. As such, we can move away from the inflexible unicast routing approach (where the destination is known before transmission), to a much more adaptive anycast [5] routing protocol. In this paper, we explore the possible gains in using OBS augmented with anycast routing, over traditional unicast routing in OCS or OBS. Grid over OBS The basic premise of Grid over OBS is the mapping of one user job into one optical burst. The user starts by creating a request burst containing job code and input data, accompanied by a burst header. This header not only contains the traditional burst-related parameters (most notably the offset between header and burst and the burst length), but also various job- related parameters, such as processing and storage requirements, time deadline, etc. In absence of an explicit destination, the OBS network is responsible for finding an available and capable resource. After successful execution, a response burst which contains the job’s results is sent back to the user. A detailed discussion of possible application scenarios and their associated resource requirements can be found in [3]. Anycast Routing Protocol in OBS The routing protocol is composed of two parts: the resource state advertisement protocol and the routing and forwarding protocol. First, each resource (i.e. edge node) periodically sends a status packet, containing the free capacity and distance in hops, to the routers (i.e. core nodes) it is attached to. In turn, these will identify the resource as being locally attached and save the status. Each router then forwards the packet to all neighbouring routers, with an updated free capacity value which is proportional to the available bandwidth between the routers (Fig. 1). Fig. 1 OBS Resource State Advertisement Algorithm Edge Node Core Node