Testing ATM Signalling Performance Application Note 
Size: 566 KB
Date: April 2000

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Early ATM switch implementations employed Permanent Virtual Connections (PVCs) between communicating endpoints. Switched Virtual Connections (SVCs) controlled by high speed signalling protocols are now widely available, allowing endpoint connections to be set up and disconnected dynamically.

For ATM to be a viable transport medium, these connections must be established at very high speeds, and may include both point-to-point and point-to-multipoint configurations.

Verifying SVC performance will be critical to the future of ATM networking solutions. To achieve the required performance levels, switch architectures are changing from centralized to distributed call processing models. It is vital that these switches be performance tested with a high rate of the types of SVC calls which cause real world load conditions.

Performance testing is a very different task than functional or conformance testing, and thus requires a different analysis approach. You aren't just testing that the switch responds properly to all different types of signalling test traffic. Rather, you are testing that the switch handles very large amounts of signalling test traffic that is sent in different ways across different ports to stress the switch in a real world fashion.

To perform this critical new testing in the best possible way, the signalling performance analyzer must be fast and flexible in terms of its number and types of ports, and have the ability to connect into different types of networks. The analyzer also needs to be flexible in terms of its use model and feature set, so that many different real world test scenarios can be created.

The UNI is the interface between the user or end station and an edge switch in the ATM network. The NNI is the interface between ATM switches. This application note discusses the key issues involved in the performance testing of ATM switches that implement the signalling protocols at the User-Network Interface (UNI), specifically in the User-to-Network direction.