Design and Implementation of the Active Image IP Multicast System

The paper presents the design and implementation of an experimental set of supplementary services over a conversational talk service in a local area network (LAN) environment, applying the principles of an intelligent structured network. The International Telecommunication Union (ITU) Intelligent Network Conceptual Model was applied as a formal framework. Special emphasis was put on the service functional modules, their decomposition on the different levels of abstraction, and the logic of their interconnection. The tools and models used in the detailed specification are referenced. The supporting intelligent local network application protocol was specified and a distributed software application was developed and implemented in the department's local network. Remote procedure call protocol software was used as an application programming interface.

The development and the implementation of a security system in a local area network environment are presented. This system is based on an extended Ethernet network, but the methodology used is transferable to different kinds of LCNs and even metropolitan area networks (MANs), with some easy modifications. The adopted solution fulfills all the requirements that must fulfill any security protocol since: it provides cryptographic security services, it is an independent algorithm, it supports transparent operations for protected systems, it does not interfere with the operation of unprotected systems, it provides protocol support of key management independent of data security, and it provides optimal communication with unprotected systems. It also offers advantages such as flexibility, simplicity, low cost, and mobility.

Over the years, the network storage bandwidth has increased rapidly while the node-to-node latency has not decreased much. This is because the latency is dominated by the protocol software execution time in the kernel, instead of by the raw transmission time over the link. Virtual Interface (VI) protocol has been proposed to overcome the software overhead of the TCP/IP. In this paper, we introduce another new technology vSCSI (VI-attached SCSI) to compete with iSCSI in LAN (Local Area Networks) environment, and compare performance of vSCSI and iSCSI experimentally. Meanwhile, we present a Virtual Interface Storage Architecture (VISA) as a new network storage architecture which uses vSCSI as the network communication protocol. Then, we can take advantage of VI’s superior performance over TCP/IP in LAN environment. Also, actually we have implemented and measured our data transport and Remote Procedure Call (RPC) layer over VI. The aim of our design and implementation is to put forward new techniques to reduce overheads.

Modeling file system organizations in a local area network environment

In recent times, the demand for multicast communications is increasing, both from internet service providers and from the content, media providers or distributors. One of the main obstacles to the wider commercial deployment of internet protocol (IP) multicast is the lack of security for the content being transmitted through IP multicast and communication infrastructure underlying IP multicast. This paper presents a multi-party key computation (MKC) protocol which provides added security to IP multicast. The group key computation, in our protocol, involves multi-party computations using one-time pad and a secret sharing scheme. The proposed protocol is secure, efficient and compatible with IPSec.

We present an evaluation of retransmission strategies over local area networks. Expressions are derived for the expectation and the variance of the transmission time of the go-back-n and the selective repeat protocols in the presence of errors. These are compared to the expressions for blast with full retransmission on error (BFRE) derived by Zwaenepoel [Zwa 85]. We conclude that go-back-n performs almost as well as selective repeat and is very much simpler to implement while BFRE is stable only for a limited range of messages sizes and error rates. We also present a variant of BFRE which optimally checkpoints the transmission of a large message. This is shown to overcome the instability of ordinary BFRE. It has a simple state machine and seems to take full advantage of the low error rates of local area networks. We further investigate go-back-n by generalizing the analysis to an upper layer transport protocol, which is likely to encounter among other things, variable delays due to protocol overhead, multiple connections, process switches and operating system scheduling priorities.

Expressions are found for the throughput and delay performance of a Tree Conflict Resolution Algorithm that is used in a Local Area Network with carrier sensing (and possibly also collision detection). We assume that Massey's constant size window algorithm is used to control access to the channel, and that the resulting conflicts (if any) are resolved using a Capetanakis-like preorder traversal tree algorithm with d-ary splitting. We develop and solve functional equations for various performance metrics of the system and apply the "Moving Server" technique to calculate the main component of the delay. Our results compare very favorably with those for CSMA protocols, which are commonly used in Local Area Networks that support sensing.

Expressions are found for the throughput and delay performance of a Tree Conflict Resolution Algorithm that is used in a Local Area Network with carrier sensing (and possibly also collision detection). We assume that Massey's constant size window algorithm is used to control access to the channel, and that the resulting conflicts (if any) are resolved using a Capetanakis-like preorder traversal tree algorithm with d -ary splitting. We develop and solve functional equations for various performance metrics of the system and apply the “Moving Server” technique to calculate the main component of the delay. Our results compare very favorably with those for CSMA protocols, which are commonly used in Local Area Networks that support sensing.

Random access algorithms have proven to be very efficient in local area network environments with data users. However, in contrast to data packets, voice packets cannot experience long delays, because of the requirement that a voice data stream must be played out at the receiver. If a voice packet exceeds its established maximum delay, it is discarded. By a simulation, the authors find the number of voice users that the network can support, provided that the packet loss rate which can be tolerated by a customer does not exceed a certain threshold. Finally, a comparison is made with the simulation results of this algorithm and other commonly used protocols. >

Adaptive video coding algorithms are digital video compression algorithms that can adapt the encoding of a video stream dynamically based on the amount of bandwidth available on the network. While such algorithms are more complicated than traditional video coding algorithms, they are attractive because of their inherent robustness to changes in network load (i.e. network congestion). Adaptive video coding algorithms seem particularly suitable for high speed network environments, such as B-ISDN/ATM, that offer Available Bit Rate (ABR) services. The goal of this paper is to assess the role that adaptive video coding algorithms will play in future high speed networks. The paper presents a simple mathematical model and analysis of several hypothetical video coding algorithms for high speed networks, and a simulation study of one such adaptive video coding algorithm that we have implemented in a local area network environment. The results show that adaptive video coding algorithms are indeed robust across a wide range of network loads. More importantly, however, the results suggest that the domain of adaptive video coding algorithm is quite narrow: moderately to heavily loaded networks with speeds on the order of 10 Mbps and 100 Mbps. As a result, adaptive video coding algorithms will likely play only a limited role in future high speed networks.

As the basic protocol for Internet communication at present, TCP/IP, which offers a unified way to communicate through different nodes, is widely applied in various communication environments and has become the basis of Internet. But the original TCP/IP protocol is designed and realized for the transmission environment of WAN Internet, it is unable to optimal fit some communication environments which may have higher requirements of real-time. This paper focuses on local area communication environment, and makes an effort to research and realize the extended TCP/IP protocol.

Fiber optics in the local area network environment must be cost competitive with copper wire solutions. In this paper several packaging solutions meeting this criteria for LED based fiber optic solutions are described. One solution involves the use of 650 nm LED packaging technology primarily designed for 960 /spl mu/m diameter plastic optical fiber but when 200 or 400 /spl mu/m diameter hard clad silica fibers are employed extended distances can be achieved. This package uses leadframe technology with clear transfer molding compound and a molded lens to achieve its performance. For 850 nm LEDs, another solution is designed for effective use with multimode glass fibers such as 62.5 /spl mu/m diameter core fiber but it can also be used with hard clad silica fibers. In this case injected molded piece parts are used for the precision ferrule sleeve and the precision secondary lens. >

Experiences with multimedia applications over native ATM

The authors present an all-optical hypercube-based multichannel network, implemented on a ring topology, using wavelength division multiplexed channels. For a network of size N, only log/sub 2/N distinct channels are required. They design an optical network interface unit (ONIU), which employs free-space optics to perform routing and switching functions. The design eliminates the electronic bottleneck at intermediate nodes and is capable of performing high speed packet switching. ONIU can be reconfigured in the GHz range and provides the high bandwidth necessary to perform distributed and parallel computing in a local area network environment. >

A distributed data system that included shared data resident in a mainframe/PC local area network environment was successfully introduced to nontechnical end-users. The system provided the end-user with the control of responsiveness and reliability inherent in local application processing, along with the back-up support and archival storage/retrieval provided by a mainframe computer. A semaphore-driven locking scheme ensured referential data integrity across the shared data system, and HASP protocols provided fast and reliable file transfer capability. The project demonstrates that distributed methods can be applied to information systems to increase their efficiency and productivity. When the resources are on hand for such a system, planning and a phased approach to the appropriate implementation can bring success even in an end-user environment. 11 refs., 2 figs.