Gte Laboratories Incorporated

Level 3 Communications, LLC

Thomas M Chen

Stephen S Liu

Michael J Procanik

A method and system for monitoring a first virtual circuit in an asynchronous transmission mode (ATM) network comprises the steps of establishing in the network a second virtual circuit with the same path and QoS parameters as the first virtual circuit, and monitoring the first virtual circuit by determining the QoS parameters of the second virtual circuit. Specifically, a monitoring station determines the QoS parameters of the second virtual circuit by inserting monitoring information in cells transmitted and received on the second virtual circuit. The monitoring station inserts the monitoring information immediately before transmitting each cell and immediately after receiving each cell. Furthermore, the monitoring station compares the QoS parameters of the second virtual circuit with the QoS parameters of the first virtual circuit to determine network alarm information.

Method and system for monitoring broadband quality of services

Management packets are defined that are modified in the payload by each node along a virtual connection and are used to measure both end-to-end QoS and specific individual intermediate node performance parameters. Management packets are implemented by defining entirely new packets or by modifying ATM OAM cells. Switches or routers for use as intermediate nodes are defined that modify the payload of the management packet and locally measure packet delay and packet loss. An intermediate node measures and records the difference between the arrival and departure times of management packets at that switch utilizing delay-stamp fields within the management packets and either the switch internal routing header or timestamp fields within the packet. At the endpoint of the virtual connection, delay-stamp fields in the management packet indicate individual node delays and the cumulative delay. An intermediate node counts the number of packets it discards and records these values in the payload of the management packet individually and cumulatively.

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Dallas, TX, United States of America

Thomas M Chen