Avaya Inc.

At&t Bell Laboratories

Lucent Technologies Inc.

At+t Corp.

Avaya Technology LLC

Telcordia Technologies, Inc.

American Telephone and Telegraph, Co.

Alcatel-lucent USA Inc.

Mark John Karol

Kai Y Eng

Bengi Karacali-Akyamac

Parameshwaran Krishnan

Jean Meloche

Clark B Woodworth

Richard Dennis Gitlin

Malathi Veeraraghavan

Ender Ayanoglu

Juan Jenny Li

Pramod Pancha

P Krishnan

Anjur Sundaresan Krishnakumar

Yu S Yeh

Zygmunt Haas

Bernard Glance

Sanjoy Paul

Eric John Diethorn

Anthony Acampora

David Y Lee

Balaji Sathyanarayana Rao

Mark A Pashan

S Jamaloddin Golestani

Michael G Hluchyj

Mario A Santoro

David Lee

Clark Woodworth

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.

Coding and packet distribution for alternative network paths in telecommunications networks

Optical bypass circuits are selected and created with a desired amount of traffic on each circuit to offload from the IP routers, the maximum possible amount of traffic. In a first phase, each node in a network independently determines the maximum number of optical bypass circuits, configured to their maximum capacity, to as many destinations, that could possibly originate at that node. The determination is made by aggregating traffic from a given traffic matrix. The optical bypass circuit transports traffic that originates at the node plus transient traffic that the node receives from other nodes. In the second phase, the node will eliminate an optical bypass circuit found in the first phase if any of its parent nodes created a necessarily longer optical bypass circuit to the same destination. In addition, if a descendent node has more aggregate traffic to fill more bypass circuits than the parent node, then the extra optical bypass circuits from the descendent node are also created.

System and method for optical bypass routing and switching

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.

Probationary admission control in relay networks

A multi-stage technique of establishing a plurality of secure strings of symbols is disclosed. In the first stage, the illustrative embodiment establishes a first-stage string of symbols with each other node. The first-stage strings are chosen from a first, small, key space, which means that they can be established more quickly than a highly secure key from a large key space. The advantage of the first-stage strings is that it enables the user to transmit secure messages more quickly than messages secured with highly secure strings. The disadvantage of the illustrative embodiment is that the first-stage strings are not as secure as strings from a larger key space. This disadvantage is mitigated, however, by the fact that the first-stage strings are only used for a short amount of time&#x2014;until the second-stage strings are established in the second stage.

Staged establishment of secure strings of symbols

A method is disclosed for conducting a search in which measurements of a time-varying property are made and updated during the search, and in which the measurements might be uncertain. In accordance with the illustrative embodiment, one or more search algorithm parameters (e.g., the maximum branching factor of a search tree, a depth cutoff for a search tree, a time cutoff, a threshold, etc.) are adjusted dynamically during the search based on at least one of: the degree of uncertainty of the measurements, the variability of measurements over time (e.g., standard deviation, etc.), and the fraction of members whose measurement is better than a threshold. In addition, the illustrative embodiment enables the search space to be pruned based on these criteria.

Adaptive parameterized search algorithm

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.

Evaluating quality of service in an IP network with cooperating relays

A method for estimating the network-layer topology of a telecommunications network is described. In particular, the illustrative embodiment of the present invention estimates the existence and connectivity of nodes in the topology based on the detection of network-wide end-to-end path intersections. This is based on the assumption that pairs of streams of packets that share a common node will interfere and that the interference can be detected in the received streams. In general, this interference is manifested as jitter. By transmitting streams on each pair of end-to-end paths in the network, and detecting interference (or a lack of interference) a matrix of path intersections for the network can be created. Using logic and supposition, the topology of the network can be estimated using the matrix of path intersections. Once the estimate of the topology is complete, the maintenance and operation of the network can proceed based on the topology.

Detecting interfering packet streams in packet networks

A method is disclosed for adaptively and intelligently partitioning traffic among a plurality of communications channels, without injecting probe traffic into any of the channels. In accordance with the illustrative embodiment, a source node transmits traffic to a receiving node via K communications channels in accordance with partition coefficients &#x3b1;, . . . , &#x3b1;, and the source node receives information regarding the quality of service (QoS) provided by each of the communications channels. The source node adjusts the values of the partition coefficients &#x3b1;, . . . , &#x3b1;adaptively based on: the current channel QoS information, prior channel QoS information, the prior values of &#x3b1;, . . . , &#x3b1;, and a measure of channel independence for one or more pairs of communications channels.

Adaptive partitioning of traffic without additional probe traffic

Techniques for performing rapid fault detection and recovery in communication networks are disclosed. For example, in one aspect of the invention, a technique for detecting one or more conditions in a communication network comprises the following steps/operations. One or more keep-alive packets are transmitted from a source node in the communication network to a destination node in the communication network over two or more paths between the source node and the destination node, wherein the two or more paths are at least partially disjoint. Upon receipt of the one or more keep-alive packets at the destination node via the two or more paths, at least one quality measure is computed at the destination node for each of the two or more paths, the at least one quality measure being indicative of one or more conditions in the communication network. While not limited thereto, the invention is particularly well-suited to Internet Protocol (IP) telephony networks, particularly those that provide Voice over IP (VoIP) applications.

Rapid fault detection and recovery for internet protocol telephony

Estimating network-layer topology using end-to-end measurements

Interfering packet streams in packet networks

A technique is disclosed that enables the adaptive pooling of M transmission paths that offer a first signal-quality guarantee, or no guarantee at all, with N transmission paths that offer a second signal-quality guarantee. Through this adaptive pooling, a telecommunications channel is created that meets the quality of service or waveform quality required for a packet stream being transmitted, while not excessively exceeding the required quality. The technique adaptively recaptures any excess signal quality from one path and uses it to boost the quality of an inferior path. A node of the illustrative embodiment selects the paths to handle a current segment of source packets, based on one or more parameters that are disclosed herein. The node adapts to changing conditions by adjusting the transmission characteristics for each successive segment of packets from the source packet stream.

Creating a telecommunications channel from multiple channels that have differing signal-quality guarantees

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.

Evaluating feasible transmission paths in a packet network

The present invention is a system and method for rapid network failure detection, identification and notification to internet users. It is particular applicable to VoIP applications where such real-time problem identification is particular valuable. It reduces failure detection time by coordinating the sending frequency of RTP and RTCP packets. These incoming packets are monitored and the failure to receive a predetermined number in a specified time window indicates that a network problem has occurred. This problem is then promptly communicated to users of the system.

System and method for notification of internet users about faults detected on an IP network

The present invention is a system and method to improve the reliability and performance of existing enterprise IP networks which have dual-homed (or multi-homed) network architectures. In one aspect of the invention packets related to a selected category of transmission (e.g., VoIP) are duplicated at an edge router and sent over both (multiple) service providers. After traversing the service provider networks, only the first-to-arrive packets are kept and the later-arriving copies are discarded. In so doing, the result is better protection against node failures, link failures, and packet errors, and also better QoS performance under normal (fault-free) operation.

Growing community of inventors

Fair Haven, NJ, United States of America

Mark John Karol