62155376
In VINI veritas: realistic and controlled network experimentation
This paper describes VINI, a virtual network infrastructure that allows network researchers to evaluate their protocols and services in a realistic environment that also provides a high degree of control over network conditions. VINI allows researchers to deploy and evaluate their ideas with real routing software, traffic loads, and network events. To provide researchers flexibility in designing their experiments, VINI supports simultaneous experiments with arbitrary network topologies on a shared physical infrastructure. This paper tackles the following important design question: What set of concepts and techniques facilitate flexible, realistic, and controlled experimentation (e.g., multiple topologies and the ability to tweak routing algorithms) on a fixed physical infrastructure? We first present VINI's high-level design and the challenges of virtualizing a single network. We then present PL-VINI, an implementation of VINI on PlanetLab, running the "Internet In a Slice". Our evaluation of PL-VINI shows that it provides a realistic and controlled environment for evaluating new protocols and services.
11321375
An overlay data plane for PlanetLab
PlanetLab is a geographically distributed overlay platform designed to support the deployment and evaluation of planetary-scale network services. It currently includes over 500 machines spanning 252 sites and 29 countries, and has supported over 450 research projects. PlanetLab can support large-scale overlays running in slices (i.e., collections of distributed virtual machines). It has significantly lowered the barriers to deploying overlays. The paper describes how to lower them further by introducing a general data plane for overlay networks. Researchers can plug their own control planes into this data plane to run fully functional overlays easily on PlanetLab, and students can use the overlay data plane as a hands-on tool for learning about internetworking concepts. The overlay data plane is the first step in the "Internet-in-a-slice" project, which will let members of the PlanetLab community experiment with virtual Internets running on PlanetLab.
57256946
Slackened Memory Dependence Enforcement: Combining Opportunistic Forwarding with Decoupled Verification
An efficient mechanism to track and enforce memory dependences is crucial to an out-of-order microprocessor. The conventional approach of using cross-checked load queue and store queue, while very effective in earlier processor incarnations, suffers from scalability problems in modern high-frequency designs that rely on buffering many in-flight instructions to exploit instruction-level parallelism. In this paper, we make a case for a very different approach to dynamic memory disambiguation. We move away from the conventional exact disambiguation strategy and adopt an opportunistic method: we allow loads and stores to access an L0 cache as they are issued out of program order, hoping that with such a laissez-faire approach, most loads actually obtain the right value. To guarantee correctness, they execute a second time in program order to access the nonspeculative L1 cache. A discrepancy between the two executions triggers a replay. Such a design completely eliminates the necessity of real-time violation detection and thus avoids the conventional approach's complexity and the associated scalability issue. We show that even a simplistic design can provide similar performance level achieved with a conventional queue-based approach with optimisticallysized queues. When simple, optional optimizations are applied, the performance level is close to that achieved with ideally-sized queues.
31352363
Some Computational Problems of Cryptographic Significance Concerning Elliptic Curves over Rings
Elliptic curves over the ring Zn were first employed by Lenstra [Len1, Len2] to present his algorithm on factorization of integers. These curves have also been used to construct new public-key cryptographic schemes [Dem, Koy, KMOV, Men]. Elliptic analogs of the RSA-scheme have been proposed in [Dem, Koy, KMOV], and an elliptic analog of Rabin-type scheme has been proposed in [KMOV]. In this paper we consider the following computational problems of cryptographic significance concerning elliptic curves over the ring Zn with n being square-free: (1) Given an odd positive integer n, and integers a, b such that 4a+27b is prime to n, to compute the number of rational points on the elliptic curve E defined by Y=X +aX+b over Zn . (2) Given an odd positive integer n, integers a, b with 4a+27b prime to n, and a point P=(u, v) on the elliptic curve E defined by Y=X+aX+b over Zn , where u, v # Zn , to find a rational point Q on E such that 2Q=P.
11321138
Attributed graph visualization of collaborative workspaces
Collaborative workspaces are becoming increasingly commonplace, particularly in large, distributed organizations where virtual teams formed in order to jointly carry out collaborative project work. Typical collaborative workspaces often have a large number of objects and relations as well as their associated domain-specific attributes. The visualization of these domain-specific attributes is the challenge of this research. This paper presents a new approach for visualizing the attributes of objects and relations in collaborative workspaces. This new visualization provides not only a structural view of the collaborative workspaces but also a graphical view of a variety of domain-specific attributes associated with collaborative objects and relations. This paper also describes a framework for the attributed visualization of collaborative workspaces.
22192509
A space-optimized tree visualization
We describe a new method for the visualization of tree structured relational data. It can be used especially for the display of very large hierarchies in a 2-dimensional space. We discuss the advantages and limitations of current techniques of tree visualization. Our strategy is to optimize the drawing of trees in a geometrical plane and maximize the utilization of display space by allowing more nodes and links to be displayed at a limit screen resolution. We use the concept of enclosure to partition the entire display space into a collection of local regions that are assigned to all nodes in tree T for the display of their sub-trees and themselves. To enable the exploration of large hierarchies, we use a modified semantic zooming technique to view the detail of a particular part of the hierarchy at a time based on user's interest. Layout animation is also provided to preserve the mental map while the user is exploring the hierarchy by changing zoomed views.
45897792
An Integrated Visual Intrusion Detection and Analysis System