Abstract: Multiple parent-dependencies are identified for messages that are received on a network that includes nodes that are configured to avoid the conventional strictly-sequential communications techniques and protocols, in order to accelerate network performance. If a network is known, or assumed, to include intermediate/proxy nodes that are configured to provide acceleration, access control, and other services, the system that analyzes traffic on the network is configured to assume that these nodes may/will provide such features, and thereby introduce multiple dependencies among the messages communicated across the network. For each message transmitted from a forwarding node, messages received at the forwarding node are assessed to distinguish messages from the destination node and messages from an other node, and a dependency is defined for each.

Abstract: A network configuration is processed to identify each policy and the criteria associated with each policy. The criteria of the policies are processed to identify a non-overlapping set of ranges of the criteria parameter, each range being associated with a particular policy or set of policies. In a preferred embodiment, the criteria include the protocol, the source and destination IP addresses, and the source and destination ports, and a default range is defined for each criteria parameter.

Abstract: The physical connection corresponding to IP tunnels in a network are found by tracing through the device configuration and routing tables at the routers in the network to determine the outbound interface associated with each tunnel endpoint, and then inferring a likely return interface associated with the opposite tunnel endpoint. Depending upon the particular configurations, a variety of tests can be applied to validate the inference. Patricia trees are preferably used to store and process the configuration data for efficient tracing through the routing tables at each router.

Abstract: A graphic user interface facilitates the hierarchical analysis of timing parameters related to network-based applications. At the top level of the hierarchy, the user is presented a summary of the delays incurred while running an application, or while simulating the running of an application, organized by delay categories, including processing delays at each node, as well as propagation delays at each link between nodes. The interface enables a user to “drill down” into lower levels of the timing information hierarchy by ‘clicking’ on currently displayed information. The information is presented in a form most appropriate to the level of analysis. The presentation forms include, for example, pie-charts, multi-variable timing diagrams (in both absolute and relative forms), data exchange charts, and so on, and ‘zoom’ capabilities are provided as appropriate to the particular display form.

Abstract: Latching elements on a first structure are configured to securely engage corresponding bearings on a second structure, via a lateral member that drives all of the latching elements simultaneously. When engaged, or when disengaged, the system is in a stable state, requiring no active force by the controlling system to maintain the system in each state. Preferably, each latching element is coupled to the lateral member via a pinion that provides a mechanical advantage that substantially reduces the force required on the lateral member to effect the coupling or decoupling. Also preferably, the elements are formed from extruded aluminum forms, thereby providing for a relatively inexpensive and lightweight configuration that is particularly well suited for spacecraft applications.

Abstract: Systems and methods are disclosed for managing services on a network. In one exemplary embodiment, the method includes receiving topologically relevant network information concerning nodes, interfaces, connections and/or protocols; resolving conflicts in the received information; determining and storing a network topology from the received and resolved information; and inferring one or more services based on the stored topology.

Abstract: First-order effects of hypothesized fault conditions are determined by propagating discrete test packets between select nodes and noting the change of path, if any, taken by the test packet under each condition relative to the fault-free path. Tools are provided to create classes of node pairs of interest, and test packets are created only for select classes. The network is analyzed to identify fault conditions that are likely to impact system performance, and only these fault conditions are simulated. By providing a methodology for selecting classes of node pairs to test, and prioritizing the faults to simulate, a first-order survivability analysis of large networks can be performed efficiently and effectively. The efficiency of this technique is also enhanced by providing test packets that are representative of a wide range of possible source-destination combinations, and by evaluating only the source-destination combinations that may be directly affected by each fault condition.

Abstract: Time-varying latency is estimated based on the round-trip time between the time of sending a message and the time of receiving an acknowledgement of receipt of the message. The round-trip time relative to a transmitter is modeled as a combination of known, or determinable, delays, plus an unknown latency, plus a processing/acknowledgement delay at the receiver. The estimated time-varying latency is further refined to give more weight to estimates based on fewer unknowns or a lesser magnitude of unknowns, and to impose physical constraints, such as assuring that the estimate does not imply an unrealizable event. TCP-specific constraints and assumptions are also applied to further refine the latency estimates.

Abstract: Application messages are segregated into message paths, and the delays of the transmitted packets associated with each message path are independently analyzed to distinguish propagation, bandwidth, congestion, and protocol delays. To further distinguish the congestion delays, all of the paths of the application messages are assessed to identify delays induced by the application, including self-congestion delay, corresponding to pre-congestion delays caused by attempting to send data from a source device faster than the bandwidth of the channel allows, and cross-congestion delay, corresponding to post-congestion delays caused by varying delays beyond a bottleneck link in the channel. The remaining congestion delay is identified as network congestion delay, corresponding to delays caused by network devices other than the source device. After identifying each of the components of delay, the effect of each component on the overall delay is determined to identify where improvements can best be made.

Abstract: An interactive system and method automates the control and management of routing changes that are focused on specific routes or particular network hot spots. Based on the premise that the user is aware of a particular problem that needs to be solved, the system leads the user through an end-to-end process from the identification of the problem to the generation of configuration instructions for effecting a selected solution. A graphic user interface provides a visualization of the current routing and alternative routings, to facilitate the analysis and selection of an improved routing, if any. Throughout the process, the effect of each proposed routing change on the overall network performance is determined, so that the selection of a preferred solution can be made in the appropriate context, and globally sub-optimal solutions can be avoided.

Abstract: A Composite Pattern with BLOB data types is used to model a hierarchical network, and includes a path-like construct for locating each component within the network model. Database procedures are used to efficiently search, modify and retrieve individual nodes from the network model using the database server's memory pool so that client applications are not required to retrieve and deserialize the entire Composite-BLOB hierarchy in order to make modifications or search for individual elements, thereby substantially reducing the transfer of data between the application layer and database. To avoid the need for dynamic memory restructuring during deserialization, the size required to store component data at each composite is stored when the composite is serialized, and during deserialization, the size is retrieved and used to obtain sufficient memory for the deserialized composite.

Abstract: Controllable operational transconductance power amplifier (controllable power OTA) including an input stage receiving a differential input signal (Ovin) and deriving therefrom first (i1) and second (i2) low power current signals being coupled to first (ccs1) and second (ccs2) current controlled output current sources being arranged in class B push pull configuration. To obtain an effective gain control while securing power efficiency and linearity, the overall gain of the power OTA is controlled by varying the gain or transconductance of the input stage (c15) and by the use of means for bi-directionally rectifying said first (i1) and second (io) low power current signals and providing in mutual alternation power amplification of said first (i1) and second (i2) low power current signals into first (I01) and second (Io2) mutually exclusive high power current output signals, which are supplied through a current summer to a current output (I0) of said linear power amplifier.

Abstract: A system/method searches a traffic stream for a sequence of “matching” packets that exhibit a high degree of correlation or similarity to a sequence of “reference” packets. The correlation between matching and reference packets is based on a degree of correspondence between individual packets, as well as the sequence-order of the corresponding packets. A variation of the Needleman-Wunsch algorithm is preferably used to select corresponding packets in the traffic stream that provide a sequence-order that best matches the sequence-order of the reference packets, based on a measure of the correspondence for each match, and a penalty associated with each non-match. The algorithm is further modified to reduce the required search-space for finding corresponding packets in the traffic stream.

Abstract: A network monitoring device configured to collect a new packet from one or more observation points of a network and to compare the new packet with a list of a number of received packets based on a packet arrival rate and to identify a duplicate packet. In particular, the number of received packets in the list is equivalent to a number of packets received within a time period, i.e. the packet arrival rate. Stated differently, the network monitoring device is to compare the new packets with received packets stored in a queue of a buffer and wherein the queue has a size based on a packet arrival rate collected at one or more observation points. In addition, the time period is further adjusted according to a threshold value. The threshold value is a variable parameter that can be adjusted to compensate for different network deployment. In one embodiment, the threshold value is a time value that is not more than a transmission time of a TCP retransmitted packet.

Abstract: A routing validation method and system identifies routers that are likely to be the cause of differences in forwarding tables associated with two versions of a network. Each destination sub-network prefix is processed to identify all the routers that exhibit differences in their forwarding table for this prefix. Each router exhibiting a difference is assessed to determine whether the difference may have been propagated to this router from another router. If the difference could not have been propagated from another router, this router is identified as a potential source of the observed difference. By eliminating routers that could have received the effects of the differences from another router, the task of identifying the root cause of the observed differences is substantially reduced in complexity.

Abstract: An existing network configuration is assessed, and potential changes to the existing configuration are identified that provide the greatest incremental improvements to the performance of the network. In a preferred embodiment, the user of the system identifies the maximum number (N) of changes that may be implemented in an existing network, and the system provides a set of possible reconfigurations, each requiring fewer than N changes. The user is presented a display of the potential improvement provided by each set as a function of the number of changes in the set, so that the relative incremental gain can be easily visualized. The objective function of the optimization may include conventional load-balancing objectives, or other objectives, such as a global minimization of path lengths.

Abstract: A receiving system allows for the coherent detection of a spread-spectrum transmission at any point in time during the transmission, thereby avoiding the need to identify the start of the transmission during the transmission-detection process. An input buffer captures the transmissions on a communication channel using a moving time-window. A detector processes a time-slice from the input buffer and identifies all of the simultaneously transmitting transmitters during that time-slice. As each transmitter is identified, the demodulator traces back-in-time to identify where the message can first be detected in the input buffer. The transmission includes suitable characteristics to facilitate detection and demodulation of the message content, but need not contain a preamble to allow the detection process.

Abstract: A distributed network monitoring system includes a central monitoring device configured to fetch network traffic information from one or more remote monitoring devices in response to receiving a notification from the remote monitoring devices that the network traffic information is available, the remote monitoring devices being communicatively coupled to the central monitoring device. The network traffic information is associated with a timestamp which indicates a time period at which the network traffic information was collected by the remote monitoring devices. The central monitoring device further synchronizes the network traffic information from the remote monitoring devices by comparing the timestamp of the network traffic information with a system timestamp provided by a system clock or network time protocol (NTP) server. The network traffic information is identified as unavailable if the timestamp cannot be located when compared to the system timestamp.

Abstract: A system and method for determining a common time base among nodes in a network by iteratively propagating timing constraints among the nodes, and determining a time-shift to apply to the time base of each node that conforms to these constraints. “Trace” files record the time of transmission or reception of packets at each node, based on the time base at the node. A fundamental constraint in a common time-based system is that the time of reception of a packet at a destination node cannot be prior to the time of transmission of the packet from a source node. A further constraint in a common time-based system is that the time of reacting to an event cannot be prior to the time of the event.

Abstract: A control node of a communication network is operated at a packet bandwidth determined according to observations of performance metrics of the network at the control point. These performance metrics may be one or more of throughput, average fetch time and packet loss. The control node is operated so as to set a control bandwidth to corresponding resonance points of the performance metrics. The resonance points are determined by scanning across a range of control bandwidths, until one or more of the performance metrics is/are optimized. The packet bandwidth is set by varying an inter-packet delay time over selected communication links at the control node.