Function test methods using test cells for ATM switching system

An ATM switching system handles many kinds of virtual paths and virtual channels, so each channel's connectivity must be confirmed from the viewpoint of maintainability. The paper presents several kinds of function test methods including a connectivity test using test cells which periodically pass through pre-determined switching path routes. These methods can be used for in-service connection testing, maximum load testing, and maximum VC multiplexing testing. Total test times are far shorter than those of the conventional method. The proposed methods can also be used to verify the multicast function provided by a switch. The paper also describes a fault diagnosis scheme that uses test cells and that can continually monitor the entire ATM connection length in the system.