Patrick J Malloy

US Patent:

6820042, Nov 16, 2004

Filed:

Jul 24, 2000

Appl. No.:

09/624092

Inventors:

Alain Cohen - Washington DC
George Cathey - Washington DC
Patrick J. Malloy - Washington DC

Assignee:

Opnet Technologies - Bethesda MD

International Classification:

G06F 1710

US Classification:

703 2, 703 13, 703 17, 703 21, 703 22, 702182, 702186, 702179, 702181

Abstract:

A simulation system and method that combines the advantages of both analytical modeling and discrete-event simulation is disclosed. In a preferred embodiment of this invention, traffic on the network is modeled as a combination of background-traffic and explicit-traffic. The background-traffic is primarily processed in an analytical form, except in the âtime-vicinityâ of an explicit-event. Explicit-events are processed using discrete-event simulation, and the modeled effects are dependent upon the background-traffic. At each occasion that the background-traffic may affect the explicit-traffic, the background-traffic is particularized into events that are modeled at the lower detail level of the explicit-traffic. In this manner, the portions of the network that are unaffected by the explicit-traffic and that have no effect on the explicit-traffic are modeled and processed at an analytical level, consuming minimal processing time and memory resources, while the portion of the network affected by the explicit-traffic and the background-traffic that affects the explicit-traffic are processed at the lower level of detail.

US Patent:

7570669, Aug 4, 2009

Filed:

Aug 9, 2004

Appl. No.:

10/914603

Inventors:

Patrick J. Malloy - Washington DC, US
Antoine D. Dunn - San Mateo CA, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

H04J 3/06

US Classification:

370516, 370503, 370507, 375356, 709248, 713400, 713500, 713502

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. By concurrently tracing traffic among multiple nodes in a network and subsequently processing the trace files to assure that each packet's transmission occurs prior to its reception, and that each reaction packet occurs after its corresponding causal packet, a correspondence between each node's time base and the common time base can be determined.

US Patent:

7729256, Jun 1, 2010

Filed:

Jul 13, 2005

Appl. No.:

11/180879

Inventors:

Patrick J. Malloy - Washington DC, US
Michael Cohen - Chicago IL, US
Alain J. Cohen - Washington DC, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

G01R 31/08
G06F 15/173

US Classification:

370235, 709224

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.

US Patent:

7839790, Nov 23, 2010

Filed:

Jul 12, 2007

Appl. No.:

11/776736

Inventors:

Steve Niemczyk - Bethesda MD, US
Patrick J. Malloy - Washington DC, US
Alain J. Cohen - McLean VA, US
Russell Mark Elsner - Bethesda MD, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

H04L 12/56

US Classification:

370238, 370231, 370236, 709224, 709235

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.

US Patent:

7843815, Nov 30, 2010

Filed:

May 22, 2007

Appl. No.:

11/752283

Inventors:

Dana Znamova - Rockville MD, US
Patrick J Malloy - Washington DC, US
John Strohm - Rockville MD, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

G01R 13/08

US Classification:

370229

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.

US Patent:

8095649, Jan 10, 2012

Filed:

Apr 1, 2008

Appl. No.:

12/060271

Inventors:

Patrick J Malloy - Washington DC, US
Alain J Cohen - McLean VA, US
Steven Niemczyk - San Francisco CA, US
Russell Mark Elsner - Bethesda MD, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

G06F 15/16

US Classification:

709224, 37039521, 370238

Abstract:

A multi-functional graphical user interface facilitates the analysis and assessment of application delays, including delays that occur on multiple paths. A trace file of an application's network events is processed to categorize the causes of delays incurred in the propagation and processing of these events. The system identifies the amount of delay (‘component delay’) that can be eliminated by eliminating each of the components of delay individually, as well as the amount of delay (‘parallel delay’) that can be eliminated by eliminating combinations of the delay components. A user interface displays the amount of reduction that can be achieved by eliminating each component delay individually and the amount of reduction that can be achieved by eliminating combinations of the individual component delays. To facilitate the analysis and assessment of these potential reductions, the interface allows the user to ‘drill down’ to view the individual delay components contained in each combination forming the parallel delays. In this manner, the user is provided a view of each of the delay components that would need to be addressed, either individually or in combination, to improve the overall application delay.

US Patent:

8140665, Mar 20, 2012

Filed:

Aug 19, 2006

Appl. No.:

11/507114

Inventors:

Patrick J. Malloy - Washington DC, US
Michael S. Canney - Cedar Rapids IA, US
Ryan Gehl - Silver Spring MD, US
Marc A. Cohen - Washington DC, US
Eric S. Nudelman - Chevy Chase MD, US
Russell Mark Elsner - Bethesda MD, US
Marc I. Schneider - Arlington VA, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

G06F 15/173

US Classification:

709224

Abstract:

A system and method for managing captured network traffic data is provided. The invention comprises a plurality of capture agents, each being configured to capture the network traffic associated with one or more applications. Each application is associated with one or more capture agents according to an application profile that is stored and maintained in a capture server. When analysis of an application's network traffic is required, the capture server contacts the corresponding capture agents according to the application profile. The capture server then effects the identification and archiving of the network traffic that corresponds to a user-defined capture condition. A database at the capture server maintains a record that associates the corresponding network traffic with the user-defined capture condition such that the corresponding network traffic can later be retrieved and analyzed using an analysis engine.

US Patent:

8195443, Jun 5, 2012

Filed:

Feb 21, 2006

Appl. No.:

11/358536

Inventors:

Patrick J. Malloy - Washington DC, US
Alain Cohen - Washington DC, US
Antoine Dunn - San Mateo CA, US
Ryan Gehl - Washington DC, US
Nishant Gupta - Rockville MD, US
Mahesh Lavannis - Rockville MD, US
John Strohm - Bethesda MD, US
Prasanna Sukumar - Germantown MD, US

Assignee:

OPNET Technologies, Inc. - Bethesda MD

International Classification:

G06F 7/60
G06F 17/50
G06F 9/44
G06F 9/45
G06F 9/46
G06F 15/16
G06F 15/177
G06F 15/173

US Classification:

703 17, 703 2, 703 13, 703 21, 703 22, 718101, 709201, 709220, 709223, 709227, 709230

Abstract:

A user interface to a network simulator facilitates the use of application layer parameters and application layer logic. The user interface is configured to allow the user to define the input in a graphic form, or a text/programming form, or a combination of both. Preferably, the user interface provides common graphic forms for both inputting the data to the simulator as well as for displaying the resultant data from the simulator, thereby easing the progression from the analysis of output from one simulation to the generation of new input for a subsequent simulation.