Journal of High Speed Networks - Volume 13, issue 3

Authors: Won, Chulho | Lee, Ben | Yu, Chansu | Moh, Sangman | Park, Kyoung | Kim, Myung‐Joon

Article Type: Research Article

Abstract: This paper presents a performance study of UDP/IP, TCP/IP, and M‐VIA using Linux/SimOS. Linux/SimOS is a Linux operating system port to a complete machine simulator SimOS. A complete machine simulator includes all the system components, such as CPU, memory, I/O devices, etc., and models them in sufficient detail to run an operating system. Therefore, a real program execution environment can be set up on the simulator to perform detailed system evaluation in a non‐intrusive manner. The motivation for Linux/SimOS is to alleviate the limitations of SimOS (and its variants), which only support proprietary operating systems. Therefore, the availability of the …popular Linux operating system for a complete machine simulator will make it an extremely effective and flexible simulation environment for studying all aspects of computer system performance, especially evaluating communication protocols and network interfaces. The contributions made in this paper are two‐fold: First, the major modifications that were necessary to run Linux on SimOS are described. These modifications are specific to SimOS I/O device models and thus any future operating system porting efforts to SimOS will experience similar challenges. Second, a detailed analysis of UDP/IP, TCP/IP, and M‐VIA is performed to demonstrate the capabilities of Linux/SimOS. The simulation study shows that Linux/SimOS is capable of capturing all aspects communication performance, including the effects of the kernel, device driver, and network interface. Show more

Keywords: SimOS, complete system simulation, Linux, instruction set simulators, UDP/IP, TCP/IP, M‐VIA

Citation: Journal of High Speed Networks, vol. 13, no. 3, pp. 169-182, 2004

Authors: Lin, Yu | Cheng, Shiduan | Wang, Chonggang | Wu, Haitao | Long, Keping | Zou, Shihong

Article Type: Research Article

Abstract: The p‐pair/train technique estimates the capacity of a path from the dispersion experienced by two/multiple back‐to‐back packets. The dispersion of packets may follow a complicated multimodal distribution, which causes statistical filtering methodologies and heuristic approaches (e.g., pathrate) to be inaccurate in heavily‐loaded cases. This paper analyzes the noise characteristics in the path capacity measurement, and elaborates on the distribution of capacity estimates. Based on this analysis, a new algorithm called LMSA (Local Modes Statistical Algorithm), and its enhancement (LMSA+) are presented. Using multiple distributions of capacity estimates obtained by variable‐sized probing p‐pairs, LMSA+ only picks out the local modes that …locates at fixed positions, and selects the minimum of these modes as the path capacity. Simulation results demonstrate that, compared with pathrate, LMSA+ is more accurate in heavily‐loaded paths or paths with relatively large bottleneck bandwidth values, and is more robust to the dynamic cross traffic load. Show more

Keywords: Active network measurements, bandwidth monitoring, bottleneck bandwidth, available bandwidth, measurement noise

Citation: Journal of High Speed Networks, vol. 13, no. 3, pp. 183-206, 2004

Authors: Lee, Chien‐Cheng | Chung, Pau‐Choo | Duh, Dyi‐Rong | Han, Yunghsiang S. | Lin, Chi‐Wei

Article Type: Research Article

Abstract: The paper presents and discusses a collaborative teleconsultation system built on next generation network (NGN) transmission considerations. Considering the capability of merging medical images with multimedia data and real‐time video conferencing in transmission provided by NGN networks, the system is built with computer‐supported cooperative work (CSCW), DICOM standard, security functions, and image processing/analysis tools. The built‐in CSCW creates a collaborative consultation environment for synchronous interactive face‐to‐face discussion. The security functions provide the privacy and integrity in patient data transmission. The DICOM standard enables the medical image access to the PACS connecting with various imaging modalities. The image processing/analysis tools supported …by CSCW functions provide useful tools for physicians to examine the images, and short‐code messages are defined to transmit the image operation command for maintaining the system consistency between users. These functions are discussed and tested on the NGN network transmission for its characteristics including transmission latency, jitter, data loss rate, and multicast performance. The experiments show that adopting the short‐code message drastically reduces the bandwidth requirement and also the user waiting time, under which the basic bandwidth requirement of the system during consultation is about 160 Kbps. The security functions occupy 92 ms and 83 ms for encryption and decryption, respectively, for a 518‐Kbytes image file. The multicast transmission technology is adopted to avoid the increase of network traffic when the number of participants expands. The experiments also show that the use of tunneling slightly increases overhead; however, the system can be deployed on the network without supporting IP multicasting via tunneling. Show more

Keywords: Computer‐supported cooperative work (CSCW), next generation network (NGN), Digital Imaging and Communications in Medicine (DICOM), security, multicasting, telemedicine

Citation: Journal of High Speed Networks, vol. 13, no. 3, pp. 207-222, 2004

Authors: Hu, Shuo‐Cheng | Chan, Chia‐Tai | Chang, Hung‐Yi | Wang, Pi‐Chung

Article Type: Research Article

Abstract: Nowadays, the commonly used table lookup scheme for IP routing is based on the so‐called classless interdomain routing (CIDR). With CIDR, routers must find out the best matching prefix (BMP) for IP packets forwarding, which complicates the IP lookup. Since the IP lookup performance is a major design issue for the new generation routers, in this article we investigate the properties of the routing table and present a new IP lookup scheme. By using the proposed scheme, the size of the forwarding table can be compressed to 360 Kbytes for a large routing table with 58 000 routing entries. The data …structure for the incremental update is also introduced by adding 40% storage. The new data structure, could accomplish a single route update within 100 ns. Even where route flaps impede lookup performance, the performance degrades by only 0.05% with 4000 route updates per second. Furthermore, this scheme is IPv6 scalable. Show more

Keywords: Routing‐table, routing lookup, Internet

Citation: Journal of High Speed Networks, vol. 13, no. 3, pp. 223-232, 2004

Authors: Kim, Myoung‐Hun | Park, Hong‐Shik

Article Type: Research Article

Abstract: We address the problem of short term QoS, caused by unexpected nature of traffic and expectation of high utilization, by using measurement based adaptive bandwidth control. We develop a short term QoS guaranteed scheduler, called short term QoS Deficit Round Robin (SQ‐DRR), which adapts the allocated bandwidth to guarantee delay constraints. The major appealing aspect of the scheduler is that it guarantees delay constraint for short term aggregate burst traffic violating pre‐contracted descriptors at the same time without losing long term fairness. We then evaluate the scheduler performance with and without admission control scheme under non‐stationary long‐range dependence traffic. The …simulation results indicate that the SQ‐DRR performs well in single‐hop and multi‐hop network under dynamic burst traffic conditions. Show more

Keywords: Scheduling algorithm, QoS, traffic management

Citation: Journal of High Speed Networks, vol. 13, no. 3, pp. 233-248, 2004