In this paper, we present the modeling, validation, and verification of an industrial protocol for constraint-based path computation, called PCEP. From the PCEP specification defined by IETF, we divide the functionalities of PCEP into two parts: application and protocol. The protocol part of PCEP is then described in the IF language which is based on communicating timed automata. A number of basic requirements are identified from the PCEP specification and then described as properties in the IF language. Based on these properties, the validation and verification of the formal specification are carried out using the IF toolset. Test cases are generated by using an automatic test generation tool, called TestGen-IF, which uses partial state space exploration guided by test purposes. As a result of the modeling, validation, and verification, some errors and ambiguities are found in the PCEP specification. Also a number of test cases are obtained which will be used for testing implementations