Bell Communications Research, Inc.

Telcordia Technologies, Inc.

Arturo Cisneros

Richard C Lau

Tirunell V Lakshman

Charles A Brackett

Gary A Hayward

Ivan P Auer

Frank C D Tsai

Richard Lau

Methods and apparatus are provided to determine performance of a network. A first measurement relating to a first layer of communications in the network and a second measurement relating to a second layer of communications in the network are provided. Based on the first and second measurements, a set of parameters is generated. The performance of the network is then determined based on the generated set of parameters.

Service performance correlation and analysis

The packet loss ratio for a network is measured using only end-point packet counter or byte counter data received from ingress and egress network elements, or all edge routers attached to edge network elements in a virtual private network (VPN). After preprocessing the packet count data from the end-points, the data signal is put through a low pass filter of one or more tap sizes to remove high frequency variations in the ingress and egress packet count data due to the inability to sample selected data sets simultaneously. After filtering the data may be integrated in order to increase detection of small amounts of data packet loss. In order to determine if measurable loss has been detected the standard deviation of the signal is calculated over a selected set of data points prior to the window in which the packet loss ratio is calculated. If the detected packet loss is greater than a predetermined detectability threshold based on the computed standard deviation for a target threshold rate for a certain filter size then the loss rate is reported.

Measurement of packet loss ratio in a network using end-point data

A system and method for equalizing delay in a dynamic packet switching network using transmit and receive buffers. The network includes a plurality of user access stations each equipped with a transmit buffer and a receive buffer, and a plurality of switches and communication links interconnecting the user access stations. A control station having communication links to the switches and user access stations operates to set up and change transmission paths between the user access stations, and to control the buffers in the user access stations to equalize packet transmission delay through the network and to eliminate packet rate doubling upon changing transmission paths. The system also includes a buffer shifting feature whereby a controlled buffering in a transmitting user access station is gradually shifted to a buffer in a receiving user access station during a period of time following a change from a longer transmission path to a shorter transmission path.

System and method for equalizing delay in a dynamic packet switching

Apparatus and methods are provided for photonic contention resolution in a switch including a plurality of input modules and a plurality of output modules, wherein at least two of the plurality of input modules have cells to be transmitted to a destination output module. The photonic contention resolution device includes a plurality of coherent light sources for emitting a beam of coherent light and a plurality of tunable receivers. Each of the coherent light sources and tunable receivers are tunable by an associated input module to a plurality of distinct wavelengths. Each tunable laser preferably illuminates at least one of the plurality of tunable receivers at the particular wavelength associated with the destination output module such that one of the at least two input modules transmits its cell to the destination output module if none of the plurality of coherent light sources is illuminating its associated tunable receiver at the particular wavelength.

Apparatus and method for photonic contention resolution in a large ATM

Apparatus and method for large scale asynchronous transfer mode (ATM) switching utilizing tunable lasers and fixed-tuned receivers are provided. The apparatus, an optical switch, includes a plurality of input modules for receiving ATM cells to be switched and a plurality of output modules for outputting the switched ATM cells. The optical switch also includes an optical transmission network for optically transmitting each ATM cell from an input module to a particular output module, and a contention resolution device in electrical communication with the plurality of input modules for selecting the ATM cells from the plurality of input modules to be switched. Preferably, each output module includes a plurality of fixed-tuned receivers and each input module includes a plurality of tunable lasers. The fixed-tuned receivers of each output module are tuned to a particular wavelength so as to pass only those ATM cells optically received from the optical transmission network at the particular wavelength. The tunable lasers are tunable to a plurality of distinct wavelengths for optically transmitting the ATM cell to the optical transmission network at the particular distinct wavelength associated with the output module to which the ATM cell is destined.

Apparatus and method for large scale ATM switching

Apparatus, and accompanying methods for use therein, for a large (e.g. approximately 1 Terabit/second), fault tolerant packet switch (200), particularly suited for asynchronous mode transfer (ATM) communication, which utilizes cell address look-ahead in conjunction with parallel planes of self-routing cross-points (550), staggered time phased contention resolution and shared memory based input and output modules (260 and 270, respectively). Each incoming packet cell has added thereto an additional header field containing information identifying a particular output module and a particular output port of that module. An input module associated with the switching crosspoints changes the additional header information to identify the particular output module of the next subsequent packet cell.

Packet address look-ahead technique for use in implementing a high speed

Apparatus, and accompanying methods for use therein, for a large (e.g. approximately 1 Terabit/second), fault tolerant packet switch (200), particularly suited for asynchronous mode transfer (ATM) communication, which utilizes cell address look-ahead in conjunction with parallel, planes of self-routing cross-points (550), staggered time phased contention resolution and shared memory based input and output modules (260 and 270, respectively). The contention resolution involves storing for each input packet in two registers the address of the incoming packet and an indication of whether that packet had priorly lost a contention resolution. In that way a fairness factor is added to the contention resolution.

Technique for resolving output port contention in a high speed packet

Apparatus, and accompanying methods for use therein, for a large (e.g. approximately 1 Terabit/second), fault tolerant packet switch (200), particularly suited for asynchronous mode transfer (ATM) communication, which utilizes cell address look-ahead in conjunction with parallel planes of self-routing cross-points (550), staggered time phased contention resolution and shared memory based input and output modules (260 and 270, respectively). An ATM cell applied to an input port of an interface module contains a data field and a virtual channel identifier (VCI) field. The VCI is translated by the interface module into a new VCI, to identify an output of the virtual channel for the switch and appends to the cell an additional routing header which will be used strictly for internal use in routing the entire cell through the switch and which includes distinct first and second portions.

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Lincroft, NJ, United States of America

Arturo Cisneros