A conformance tester for X.25 DTE implementations

The authors review briefly the testing architecture of ISO 9646, a standard for defining testing methodology and architecture for all of the ISO Open Systems Interconnection layers. They then describe the test systems of the US National Institute for Standards and Technology for both the link and packet layers, and, for vendors interfacing their data terminal equipment to DDN. They explain how conformance to the Defense Data Network (DDN) X.25 interface can be verified. They also discuss the possibility of porting the test system to other test equipment