Showing papers on "Virtual network published in 1995"

Virtual local area network well-known port routing mechanism for mult--emulators in an open system environment

Abstract: A local host data processing system operating under the control of a local host operating system includes components of multiple emulating hosted operating systems. The host operating system further include a TCP/IP network protocol stack which couples to the communications facilities of the host system connected to a local area network for communicating with a number of remote host systems. Host and hosted operating systems share the same TCP/IP network protocol stack. A virtual network mechanism is configured within the local host system to be operatively coupled to the host network protocol stack and provide access to well-known port application programs. When so configured, the mechanism functions as another LAN to which multiple virtual host systems are attached for executing applications under control of the emulating hosted operating systems. The mechanism transforms the well-known port identifier of each inbound packet into a non-well-known port identifier in addition to other station address identifier fields. It then redirects the transformed packet back to the IP layer of the stack for transfer to the appropriate well-known port application program being run by the hosted operating system of the particular virtual host system. The mechanism reverses this operation for each reply packet which it redirects back to the IP layer for forwarding to the remote system. This eliminates the need to specify additional protocol stacks and to provide additional communication hardware facilities for handling multiple instances of well-known port applications programs running on the different virtual host/multiple hosted operating systems.

Method and apparatus for routing for virtual networks

Abstract: An internetwork routing protocol which supports virtual networks Routing tables are maintained in routers or gateways which identify whether or not a destination is directly reachable by the router listed in the routing information entry, or whether it is merely part of a virtual network served by the listed destination routers For directly reachable connections, datagrams may be directly delivered to any router claiming such status with respect to the network with assurance of likely delivery to the destination Routers in communication with a virtual network must first be queried for the identity of a particular destination router address before packets are delivered to eliminate the need of packet forwarding

Method and apparatus for configuring a virtual network

Abstract: A method of configuring a network. The network includes some physical devices, some hosts, and a network management tool. The method comprises the following steps. First, generate a set of leaf nodes. Each leaf node includes at least one physical device and connects to at least one host. Next, generate an adjacency matrix from said set of leaf nodes. Next, generate a set of interconnect nodes, the interconnect nodes connect the set of leaf nodes. Next, determine the resource availability for the set of interconnect nodes. Finally, configure the set of interconnect nodes and the set of leaf nodes after determining that sufficient resources are available.

Algorithms for Optimized Node Arrangements in ShuffleNet Based Multihop Lightwave Networks

Abstract: The capabilities of emerging optical technology, viz. dense wavelength division multiplexing (WDM) and tunable optical transmitters and receivers (transceivers) can be exploited to construct lightwave networks, as follows. First, by employing WDM, the huge optical bandwidth (in the order of Terahertz) is partitioned into a number of smaller capacity channels (in the order of Gigahertz) which are compatible with the electronic interface speeds. Second, each node with its tunable transmitter(s) and receiver(s) can access a subset of the available channels by tuning its transceivers to the appropriate wavelengths. Now, the system can be configured as a broadcast-and-select network in which all of the inputs from various nodes are combined in a star coupler and the mixed optical information is broadcast to all the outputs. Thus, a multitude of virtual network configurations can be superimposed over any given physical network topology.The goal of this study is to exploit the aforementioned capabilities of lightwave technology in order to construct optimized regular multihop networks when the traffic flow among the network nodes is asymmetric. The specific problem addressed here is as follows: Given that the network nodes must be connected in a regular interconnection pattern and that the node positions in the regular network can be adjusted by properly tuning their (optical) transceivers, what is the best node placement in a given regular topology? We have chosen ShuffleNet based regular structure as the model of our network topology. ShuffleNet can interconnect a large number of nodes with a small number of transceivers per node such that information from a source can reach its destination in a small number of hops. However, finding the optimal node placement is a computationally hard problem. So, we formulate efficient heuristic algorithms to design optimized ShuffieNet structures for a given traffic matrix. Also, a scheme is developed to dynamically rearrange the logical node positions to a new optimized configuration, within the ShuffleNet framework, when the pattern of offered load changes.

Architectural support for mobile objects in large scale distributed systems

Abstract: The paper discusses the relevant features of an object support system that provides basic facilities for building flexible distributed applications in environments where objects can be mobile and occasional failures (node crashes, real or virtual network partitions) are possible. These facilities are for naming, locating and invoking objects, persistence and garbage collection. One of the key features is an efficient and reliable object reference scheme that is particularly good for dealing with mobile objects. The design presented scales to systems of arbitrary size and is portable since it only requires a few standard capabilities from the underlying operating system. >

Virtual network controlling method

Abstract: PROBLEM TO BE SOLVED: To facilitate the batch control of a complicated virtual network and to automatically perform the reconstitution and the change of a virtual network. SOLUTION: In this system, plural ports 1 to 5 with which each node 21 to 31 is connected and switching hubs 11 to 13 having bridge functions are connected via an ATM network 10, prescribed ports are divided into groups between other switching hubs, the setting of a virtual LAN is performed and data is transmitted to a node to be a transmission origin and the node of the same group. In this case, a VLAN server 14 storing the MAC addresses of the nodes and VLAN identification data by making them correspond is connected with the ATM network, a batch control of all the nodes is performed on the VLAN server by the MAC addresses and the reconstitution and the change of the VLAN are performed. COPYRIGHT: (C)1997,JPO

Virtual instruments for development of high performance circuit technologies

Abstract: A set of virtual instruments based on computer-aided design tools for technology (TCAD) are described. These virtual instruments support the evaluation of new technologies for circuit applications, including both intrinsic and parasitic effects. Mixed-mode (circuit/device) simulation in both the frequency and time-domain is demonstrated including an example of a virtual network analyzer applied to evaluation of a GaAs FET. Virtual curve-tracing is demonstrated as a powerful means to obtain I-V curves and to zoom in on the regions of device characteristics where SPICE model parameters can effectively be extracted and parasitic effects such as failure mechanisms due to electrostatic discharge (ESD) can be analyzed. Finally large signal distortion behavior analyzed based on the device simulation using the harmonic balance (HB) method is demonstrated with application to extraction of intermodulation (IM) distortion in bipolar transistor circuits.

Test system for inter-network connection device

Abstract: PURPOSE:To test the inter-network connector by realizing an equivalent environment to an actual network with a virtual network and a virtual terminal equipment group. CONSTITUTION:A test exclusive terminal equipment 120 is connected to an inter-network connection device 100 being a test object by a line 110. A network learning section 122 of the terminal equipment 120 generates a network information table 125 managing network information of a virtual network and a virtual terminal equipment group under its control based on entry information from the operator and sends the content of the inter-network connection device 100 to register the content to a network learning table 101 thereby allowing the inter-network connection device 100 to learn the virtual network. Then a test section 123 of the terminal equipment 120 generates a test data frame based on the network information table 125 and sends the frame to the inter-network connection device 100 to confirm its reception reply.

Adaptive wormhole routing in k -ary n -cubes

Abstract: Distributed memory multiprocessor (DMMP) systems have gained much attention because their performance can be easily scaled up by increasing the number of processor-memory modules. The k-ary n-cube is the most popular interconnection network topology currently used in DMMPs. Wormhole routing is one of the most promising switching technology and has been used in many new generation multicomputers. Wormhole routing makes the communication latency insensitive to the network diameter and reduces the size of the channel buffer of each router. The concept of virtual channels and virtual networks are widely invented for deadlock-free design. A fully adaptive wormhole routing method for k-ary n-cubes has been proposed by Linder in 1991 [10]. Unfortunately, the need of 2n − 1 virtual networks makes it unreasonable. In this paper, we propose a virtual network system to support an adaptive, minimal and deadlock free routing in k-ary n-cubes. It uses only four virtual networks but can get a higher degree of adaptability and higher traffic capacity. Simulation results are presented to verify the performance.

Satellite communication systems for multimedia services

Abstract: This paper proposes a satellite communication system configuration suitable for multimedia communication and discusses the requirements for the network system. In the proposed system, multi-speed digital data is multiplexed and distributed to users by satellites. The distribution data is received not only at users' homes directly but also at the head-ends of CATV systems. Users can get desired information from multiplexed data by using a multimedia adapter consisting of a receiver and a decoder. Each user can send requirements to the information providers (IPs) via individual low bit-rate lines and the IPs can manage and maintain the user orders through those lines. The satellite network will exist not as a stand-alone system but as a virtual network in B-ISDN, which will be combined with terrestrial optical fiber links, radio links, and satellite links. As the first step in achieving a multimedia service network, a high bit-rate satellite system and a medium bit-rate satellite system are developed. In the former system, a high bit-rate transmission capability of 156 Mbps is attained. In the latter system, a very small transportable earth station of 1.2-m phi antenna is actualized. To clarify the effectiveness of using satellite communication systems for multimedia services, a demonstration using transportable earth stations of the medium bit-rate satellite system is now being carried out. >

Enhancing ATM Network Performance by Optimizing the Virtual Network Configuration.

Abstract: Virtual or logical subnetworks are expected to play an important role in large B-ISDN configurations. This gives an additional degree of freedom to ATM network architectures, since even for a fixed physical network the logical configuration can still vary depending on particular demands and conditions. This new degree of freedom calls for new solutions to utilize the opportunity for the potential enhancement of network performance by optimizing the logical configuration, as part of optimizing the distributed network architecture. In this paper a framework and model, along with efficient solution algorithms, are presented to dimension virtual ATM networks on top of the same physical infrastructure network, such that the virtual networks share the infrastructure, while the total network revenue is optimized. The algorithms are tried on various network scenarios and a trade-off between the quality of the result and running time is exhibited.

Hierarchical Adaptive Routing Under Hybrid Traffic Load

Abstract: In actual multicomputer networks, communications consist of hybrid traffic, a mix of short and long messages.Typically, the short messages are used to support synchronization, global combining, and multicasting where the latencies are critical to the execution time of whole parallel program. However, in normal wormhole routed networks without packetization, the presence of long messages degrades network performance of short messages dramatically, qualitatively changing network behaviour. In this paper, we extend one existing adaptive routing framework, Hierarchical Adaptive Routing (HAR) to a hybrid traffic model, to form a new simple and efficient adaptive routing framework called Hybrid-HAR. Hybrid-HAR has four important advantages. Firstly, without packetization, the impact of long messages on short messages is very small. Secondly, it supports fully adaptive routing to both short and long messages for high communication performance. Third, the implementation complexity of Hybrid-HAR is compatible to standard routing algorithms such as Dimension Order Routing. Fourth, Hybrid-HAR is applicable to a wide variety of network topologies. High level implementation and simulation studies of a Hybrid-HAR for 2D mesh networks are presented.

System for use in the manufacture of articles such as glass or plastic containers

Abstract: A control system for use in the manufacture of glass and plastic containers is disclosed which has at least two nodes or computers (A, B, AA) connected by a network or more than one network. Each node (A, B, AA) has a local virtual network process which establishes a connection of its own database(s) so that a node can transparently communicate with any other node on its network or on any connected network.