Abstract: An apparatus and method are disclosed that enable a first telecommunications endpoint to ensure that a second endpoint is receiving the first endpoint's packet stream transmissions with a satisfactory waveform quality. When the second endpoint receives the packet stream, it decodes the media waveform from the stream, encodes the waveform back into a second packet stream, and transmits some or all of the packets in the second stream back to the first endpoint. The first endpoint then decodes the received waveform in the second stream and compares it to the original waveform transmitted to the second endpoint. Based on the comparison, the first endpoint adjusts the value of a quality indication, and provides the quality indication to its user and to the second endpoint. Advantageously, the user at the second endpoint is able to determine whether the received waveform is, in fact, close enough to the waveform that the first endpoint's user intended to be received and understood.

Abstract: A network condition capture and reproduction technique captures measurement data characterizing network conditions at a given time between first and second endpoint devices of a network, and utilizes the captured measurement data in a network impairment device to reproduce the network conditions at a later time and possibly in a different place.

Abstract: Systems and methods are presented for partitioning end-to-end performance effects using network tomography. In one embodiment, a method for partitioning end-to-end performance effects within a network is presented. The method includes determining a network topology between at least two test points, obtaining an unrelated approximation of edge effects between the test points, measuring end-to-end performance data between the test points corresponding to a target application, regularizing an estimate of edge effects for the target application using the unrelated approximation of edge effects, and computing the estimate of edge effects for the target application to partition the end-to-end effects.

Abstract: Node merging methods and apparatus are disclosed for generating simplified representations of network topology. A first topology representative of a given network is determined, and at least one pair of nodes of the first topology is merged into a single node based on measures associated with respective edges connecting the nodes of the node pair to at least one neighbor node common to that pair. The merging step is repeated for one or more additional pairs of nodes to produce a reduced network topology meeting one or more desired criteria, and a visualization or other representation of the reduced network topology is generated.

Abstract: A method of internet protocol (IP) address de-aliasing that involves obtaining IP addresses from devices in a network, pinging pairs of the IP addresses by sending packets to pairs of the IP addresses, obtaining ping response orders for the packets, and determining whether the pairs of IP addresses are aliases of the same network device based on the obtained ping response orders.

Abstract: Route asymmetry is detected in a network by running a route tracing program to trace routes between a first element of the network and a second element of the network. The route tracing program need be run at only a single network element, such as the first network element. Forward and reverse routes between the first and second network elements are identified as asymmetric if performance data from the route tracing program indicates a significant deviation from an expected monotonic characteristic as a function of time-to-live values of respective packets transmitted by the route tracing program.

Abstract: A technique is disclosed that enables telecommunications endpoints to conveniently share the addressing information—that is, the Uniform Resource Identifiers (URI)—of documents that are available on the World Wide Web. In particular, a server is used to provide a bookmark service. The server acts as a repository of tag-URI pairs, in which each tag functions as a shorthand label for the corresponding URI. In the disclosed technique, a first user creates the tag for the intended URI by assigning a keyword to represent the URI as part of a bookmark tag-URI pair that the server stores. The created tag is presumably shorter than the URI that it represents, making the tag more convenient to use. A second user is then able to retrieve and use the URI by specifying the tag to the bookmark server. In essence, the technique of the illustrative embodiment enables the sharing of Web documents by sharing the bookmarks to those documents.

Abstract: A network monitoring and analysis system is configured to include a root cause analysis function that permits the automatic determination of performance problem locations in a network of a communication system comprising a plurality of endpoint devices. Test communications are generated in the system in accordance with a selected pattern, which may be based on a flow matrix, and end-to-end path measurement data is collected utilizing the generated test communications. The end-to-end path measurement data is transformed to produce a plurality of performance indicators comprising a performance indicator for each of a plurality of non-end-to-end paths defined at least in part by the selected pattern.

Abstract: Systems and methods for constructing and maintaining a peer-to-peer overlay graph are disclosed herein. The systems and methods include adding a node to the overlay graph. Adding the node includes choosing an edge that is not connected to the node, breaking the edge and connecting the node to broken edge nodes previously connected to the edge. The process is repeating if additional connections are need and node addition data is stored for the node.

Abstract: A technique is disclosed that attempts to improve the evaluation of a network path's signal quality, as well as the selection of a network path for transmission purposes, without some of the costs and disadvantages of doing so in the prior art. In accordance with the illustrative embodiment, a node with access to the packet network, such as a VoIP telephone endpoint, evaluates the quality of service that is associated with each of multiple network paths. The evaluation process is iterative, in which the number of candidate paths is successively reduced from one iteration of the technique to the next. The multiple paths that remain as candidates in any given iteration are evaluated concurrently and at an evaluation bit rate that i) is less than the full transmission rate of the real-time traffic (VoIP) packets to be sent and ii) varies as a function of the number of candidate paths remaining under consideration.

Abstract: Performance problems or other conditions are analyzed in a system comprising a plurality of endpoint devices and an associated centralized or distributed controller. End-to-end measurements are obtained for respective paths through the network, for example, using communications between the endpoint devices. For a given end-to-end measurement obtained for a particular one of the paths, a value of a performance indicator for the path is determined and the performance indicator value is assigned to each of a plurality of links of the path. The determining and assigning operations are repeated for additional ones of the end-to-end measurements, the links are grouped into one or more exculpation or inculpation sets based on how many times a particular performance indicator value has been assigned to each of the links, and the one or more sets are utilized to determine, for example, the location of a performance problem in the network.

Abstract: A technique that seeks to direct and re-direct streams of packets through a packet network without adversely affecting the quality of service of existing streams is disclosed. In accordance with the illustrative embodiment of the present invention, streams of packets that are directed and re-directed through a packet network are initially put on probation. During the probation period, a quality-of-service measure for the stream is compared with a threshold whose value is initially high and decreases with time. This has the advantageous affect of noticing problems quickly so that they can be remediated quickly.

Abstract: A method and apparatus for testing a digital network having a plurality of subnetworks by determining by one of a plurality of user endpoint devices assigned to one of the plurality of subnetworks upon the one of the plurality of user endpoint devices being idle that the one of the plurality of user endpoint devices should perform the functions of a testing user endpoint device for the one of the plurality of subnetworks; identifying the one of plurality of user endpoint devices to a server or a distributed system of servers as a testing user endpoint device; obtaining the identifies of other testing user endpoint devices in other ones of the plurality of subnetworks from the server; and testing the network by transmission of test packets to other ones of the testing user endpoint devices in the other ones of the plurality of subnetworks.

Abstract: A distributed monitoring system comprises a plurality of agents configured for communication with at least one central server. A given one of the agents obtains measurement data, and applies a statistical test to the measurement data. Based on a result of the statistical test, the given agent determines whether or not an update needs to be sent by the agent to the central server. The agent sends the update to the central server if the determination indicates that the update should be sent.

Abstract: Techniques are disclosed for improved monitoring and analysis of VoIP communications, multimedia communications or other types of network traffic in a network-based communication system. In accordance with one aspect of the invention, an endpoint device of the system includes an integrated call synthesis capability. More particularly, the endpoint device is configurable into at least a first mode of operation in which the device responds to one or more commands from a testing server of the system directing the device to participate in a synthetic call or other test communication within the system, and a second mode of operation in which the device is utilizable by a system user to establish an actual communication. Other aspects of the invention relating to kernel timestamping and timestamp post-processing provide improved accuracy for measurements such as jitter, loss and delay.

Abstract: A method and apparatus are disclosed that seek to improve the quality of service that is experienced during the transmission of a stream of packets across one or more paths. In particular, a transmitting node encodes a source stream of data (e.g., audio, video, etc.) into one or more sub-streams, and distributes those sub-streams onto multiple network transmission paths. In accordance with the illustrative embodiment of the present invention, the transmitting node evaluates the quality of service of a first network path that fails to provide a quality-of-service guarantee. When the quality of service of the first network path becomes unsatisfactory, the coding of one or more sub-streams that are being transmitted on a second network path is adjusted. In other words, the coding on a second channel is adjusted in response to the changing conditions on a first channel.

Abstract: A technique is disclosed that evaluates a network path between (i) a first node in a first subnetwork of endpoint nodes, such as IP phones, and (ii) a second node in a second subnetwork. A “ricochet” node in the network path evaluates the path by probing one or both subnetworks, where the ricochet node acts as relay for traffic packets being transmitted between the two subnetworks. A given relay has only to probe a single, representative node within a subnetwork at any given time in order to obtain performance data that is representative of the subnetwork overall. By probing the representative node, the relay is able to acquire an assessment of network conditions that is valid for the path between the relay and any endpoint in the subnetwork. As a result, the disclosed technique reduces the probing overhead when many endpoint nodes on a given subnetwork are simultaneously active and experiencing adverse network conditions.

Abstract: A method that seeks to provide a satisfactory quality of service for a stream of packets through a network. The illustrative embodiment of the present invention seeks to provide a satisfactory quality of service for a stream of packets by periodically or sporadically evaluating one or more alternative paths through the network and by sending the packets through a path with an acceptable quality of service. Normally, neither the source node nor any other node in a packet's path controls its route after it has left the node. In contrast, the illustrative embodiment of the present invention has the capability to affect the packet's path through the network by sending the packet to an intermediate or “ricochet” node in the network, which forwards the packet to the destination node. In effect, the source node can, if it deems appropriate, ricochet the packet off of the intermediate node rather than allowing the packet to take its normal direct path through the network.

Abstract: Techniques are disclosed for improved monitoring and analysis of VoIP communications, multimedia communications or other types of network traffic in a network-based communication system. In accordance with one aspect of the invention, endpoint devices of the network-based communication system are configurable so as to collectively implement a distributed monitoring and analysis system which does not require a centralized testing server or other centralized controller. Distributed test units associated with the endpoint devices may be utilized in implementing the distributed monitoring and analysis system, and are preferably configured to support a web-based user interface providing access to measurement data. The endpoint devices may be advantageously organized into a hierarchy comprising a plurality of zones, with each of the endpoint devices belonging to at least one zone.

Abstract: Techniques for determining a problem location or otherwise characterizing a network comprising a plurality of processing elements, including at least one processing element associated with performance of a packet encapsulation operation of an encapsulation protocol. The packet encapsulation operation is performed on a test packet to generate an encapsulated packet, the test packet having a time to live (TTL) value and an identifier. In conjunction with performance of the packet encapsulation operation, the TTL value and the identifier of the test packet are copied to a header of the encapsulated packet. The encapsulated packet is transmitted, and a determination is made as to whether a reply packet has been received responsive to transmission of the encapsulated packet. The reply packet, if any, is processed to obtain information utilizable in determining the problem location or otherwise characterizing the network.