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GTE Laboratories
April 2, 1995


? ATM networks support voice, video, and data services over CBR/ VBR connections with guaranteed quality of service (QOS)
? QOS can be degraded by congestion, faults, etc.
? network providers need to detect and diagnose troubles quickly to
minimize their effect on users

? Out-of-service testing:
? performance measurements under controlled traffic conditions
? service is interrupted

? In-service QOS monitoring:
? continuous performance measurements with actual user traffic
? no service interruption