Generation of test cases from a protocol specification for the purposes of testing both control and data flow aspects of a protocol implementation is a challenging problem .In this paper , we propose a testing method , based on construct type algebra , which combined control and data flow .We also provide one algorithm of generating test cases based on this testing method , another algorithm of transforming a specification of

Finite State Machine to specification of Construct Type Algebra .The use of this method is illustrated by a practical example of testing the routing protocol RIP.

construct type algebra , formal description , conformance testing ,