59792527
International text in JDK 1.2
5625582
Experimental evaluation of the Hewlett-Parkard exemplar file system
This article presents results from an experimental evaluation study of the HP Exemplar file system. Our experiments consist of simple micro-benchmarks that study the impact of various factors on the file system performance. These factors include I/O request/buffer sizes, vectored/non-vectored access patterns, read-ahead policies, multi-threaded (temporally irregular) requests, and architectural issues (cache parameters, NUMA behavior, etc.). Experimental results indicate that the Exemplar file system provides high I/O bandwidth, both for single- and multi-threaded applications. The buffer cache, with prioritized buffer management and large buffer sizes, is effective in exploiting temporal and spatial access localities. The performance of non-contiguous accesses can be improved by either using vectored I/O interfaces or tuning the read-ahead facilities. The file system performance depends on the relative locations of the computing threads and the file system, and also on various Exemplar design parameters such as the NUMA architecture, TLB/data cache management and paging policies.
2180308
RARE - Resource Aware Routing for mEsh
An important element of any routing protocol used for wireless mesh networks (WMNs) is the link cost function used to represent the radio link characteristic. The majority of the routing protocols for WMNs attempt to accurately characterise the radio link quality by constructing the link cost function from the measurements obtained using active probing techniques, which introduces overhead. In this paper we propose a new approach called resource aware routing for mesh (RARE) which instead employs passive monitoring to gather radio link information. This results in a smaller overhead than the other methods that require active network probing, and is load independent since it does not require an access to the medium. Moreover, we show that our RARE approach performs well in a real radio environment through a number of experiments performed on a static 17 node WLAN mesh testbed.
6738991
An Experimental Investigation of IEEE 802.11e TXOP Facility for Real-Time Video Streaming
Real-time multimedia streaming applications require a strict bounded end-to-end delay and are considered to be bursty as each video frame is typically transmitted as a burst of packets. In this paper we show how the distribution of video frame sizes can be used to efficiently dimension the IEEE 802.lie TXOP limit parameter to efficiently deal with this burstiness in order to enhance the transmission of real-time video streaming services. Through experimental investigation, we show that by using the mean video frame size to dimension the TXOP limit parameter, the transmission delay for the video frame is reduced by 67% under heavily loaded conditions. Other techniques investigated in this paper include applying the TXOP facility separately to each of the constituent I, P, and B video frame types.
6966708
Countering Hostile Forensic Techniques
Digital forensic investigations can be subverted by hostile forensic techniques and tools. This paper examines various hostile forensic techniques, including the exploitation of vulnerabilities in standard forensic procedures and denial of service attacks on forensic tools during imaging and analysis. Several techniques for concealing evidence within file systems and external to file systems are highlighted. In addition, strategies for countering hostile forensic techniques and tools are discussed.
18478829
Gauging VoIP call quality from 802.11 WLAN resource usage
In this paper we experimentally study the relationship between resource utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how its overall capacity is shared between three basic MAC bandwidth components (load, access, and free) as the number of VoIP calls increases and how it influences transmission impairments (delay, loss, and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a WLAN probe application that passively "sniffs" packets at the L2/MAC layer of the wireless medium and analyses their headers and temporal characteristics. The quality of VoIP calls is predicted using an extended version of the ITU-T E-model, which estimates user satisfaction from time varying transmission impairments. Through experimentation with various codecs and packetization schemes we found that as the load (number of calls) reaches the available capacity level, packet delays and jitter increase dramatically resulting in the call quality becoming degraded. We show how these MAC bandwidth components maybe used to assess the VoIP call quality on 802.11 WLANs
27004101
A Network-Based Architecture for Storing Digital Evidence
The storage and handling of digital evidence are creating significant challenges for federal, state and local law enforcement agencies. The problems include acquiring and processing massive amounts of digital evidence, maintaining the integrity of the evidence, and storing digital evidence for extended periods of time. This paper describes a network-based storage architecture that helps address these issues. The architecture also supports collaborative efforts by examiners and investigators located at geographically dispersed sites.