62540784
Customer-managed end-to-end lightpath provisioning
Customer-owned and managed optical networks bring new cost-saving benefits. Two types of such networks are becoming widely used: metro dark fiber networks and long-haul leased wavelength networks. Customers may invoke a special QoS mechanism where end-to-end (E2E) lightpaths are dynamically established across multiple independently managed customer domains. The cost of bandwidth is substantially reduced since it largely becomes a capital cost rather than an ongoing service charge. Customers can optimize the overall resource consumption by utilizing resources from different suppliers. Remote peering and transit reduce the Internet connectivity cost. Bandwidth and quality of service are guaranteed because customers directly peer with each other using transport networks. An architecture for a customer-managed E2E lightpath provisioning system is presented. Integration with Grid applications is discussed and a prototype demonstration is described.
59008197
A cycle-based rerouting scheme for wavelength-routed WDM networks
In this paper, we propose a cycle-based rerouting scheme (CRS) for link restoration in wavelength-routed WDM networks. The CRS is based on a scalable set of Pcycles covering a mesh network. Instead of using these Pcycles as enhanced self-healing rings as in traditional approaches, the CRS decomposes these P-cycles into rerouting paths for the links that the P-cycles cover. In this way, flexible and cost-effective link restoration is achieved. Simulation results show that the rerouting performance of the CRS can be very close to the theoretical upper bound.
14750805
Deadlock-Free Routing In Irregular Networks Using Prefix Routing
We propose a deadlock-free routing scheme in irregular networks using prefix routing. Prefix routing is a special type of routing with a compact routing table associated with each node (processor). Basically, each outgoing channel of a node is assigned a special label and an outgoing channel is selected if its label is a prefix of the label of the destination node. Node and channel labeling in an irregular network is done through constructing a spanning tree. The routing process follows a two-phase process of going up and then down along the spanning tree, with a possible cross channel (shortcut) between two branches of the tree between two phases. We show that the proposed routing scheme is deadlock- and livelock-free. We also compare prefix routing with the existing up*/down* routing which has been widely used in irregular networks. Possible extensions are also discussed.
1582691
The effect of compression on performance in a demand paging operating system
Abstract As engineers increase microprocessor speed, many traditionally computer-bound tasks are being transformed to input/output (I/O) bound tasks. Where processor performance had once been the primary bottleneck, I/O performance is now the primary inhibitor to faster execution. As the performance gap widens between processor and I/O, it is becoming more important to improve the efficiency of I/O in order to improve overall system performance. In a demand paging operating system, secondary memory is accessed during program execution when a page fault occurs. To improve program execution, it is increasingly important to decrease the amount of time required to process a page fault. This paper describes a compression format which is suitable for both pages of code and pages of data. We find that when the OS/2 operating system is modified to use this compression format, the time saved due to reduced I/O offsets the additional time required to decompress the page.
8943672
Enhanced Fibonacci Cubes
We propose the enhanced Fibonacci cube (EFC) structure for parallel systems. It is defined based on the sequence F n = 2F n-2 + 2F n-4 . We show that the enhanced Fibonacci cube contains the Fibonacci cube (FC) as a subgraph and maintains virtually all the desirable properties of the Fibonacci cube. In addition, it is a Hamiltonian graph. We can embed complete binary trees into enhanced Fibonacci cubes with dilation one and with a relatively small expansion. We also propose a series of enhanced Fibonacci cubes EFC (k) , where k is a series number. Each EFC (k) contains an FC of the same order as a subcube. Moreover, each EFC (k) in the series contains any other cube that precedes it as subcubes and the last one in the series is a hypercube of the corresponding order. This series of EFC (k) s provides us with more options for selecting cubes with various sizes. Because EFC is a subgraph of the hypercube, it may find applications in fault-tolerant computing for degraded hypercube computer systems. As an application of EFC, we show that the parallel prefix sum computation can be efficiently implemented on enhanced Fibonacci cubes.
5896177
Fault-tolerant routing in meshes/tori using planarly constructed fault blocks
A few faulty nodes can make an n-dimensional mesh or torus network unsafe for fault-tolerant routing methods based on the block fault model, where the whole system (n-dimensional space) forms a fault block. A new concept, called extended local safety information in meshes or tori, is proposed to guide fault-tolerant routing, and classifies fault-free nodes inside 2-dimensional planes. Many nodes globally marked as unsafe become locally enabled inside 2-dimensional planes. A fault-tolerant routing algorithm based on extended local safety information is proposed for k-ary n-dimensional meshes/tori. Our method does not need to disable any fault-free nodes, unlike many previous methods, and this enhances the computational power of the system and improves performance of the routing algorithm greatly. All fault blocks are constructed inside 2-dimensional planes rather than in the whole system. Extensive simulation results are presented and compared with the previous methods.
2242460
Deadlock-Free Multicasting in Irregular Networks Using Prefix Routing
A deadlock-free multicast scheme called prefix multicasting in irregular networks (i.e., networks with irregular topology) is studied. In prefix routing, a compact routing table is associated with each node (processor). Basically, each outgoing channel of a node is assigned a special label and an outgoing channel is selected if its label is a prefix of the label of the destination node. Node and channel labelling in an irregular network is based on a pre-defined spanning tree which may or may not be minimum. The routing process follows a two-phase process of going up and then down along the spanning tree, with a possible cross channel between two branches of the tree between two phases. It is shown that the proposed routing scheme is deadlock- and livelock-free. The approach is extended to multicasting in which the multicast packet is first forwarded up the tree to the longest common prefix (LCP) of destinations in the multicast. The packet is then treated as a multi-head worm that can split at branches of the spanning tree as the packet is sent down the tree.