Research On Network Protocol Modeling And Interoperability Testing Based On Property

Internet is world widely network. Its products can be built by many different manufactures, therefore they need interoperability testing. Interoperability testing is to check whether two or more implementations can interact correctly and offer expected service, it is a basic guarantee for interconnecting network devices and transporting the information between these products.The generic process of interoperability testing includes SUT(System under Test) modeling, test sequence generation and test deployment and execution. The nondeterminism in specification is analyzed and the test experience results are made use to model the situation. A new test selection method is introduced. Properties are the functions or features of one system. Interoperability testing based on property can be divided into four parts:the construction of Petri net for SUT base on property, the executable test sequence generation based on reachable graph with property coverage consideration; the test data generation. Modeling SUT base on property generally can reduce the workload of model construction because it only focuses on the interested properties and ignores the others. The definitions of obligation property, interactive property and extensible property as well as the related models are puting forwarded. The test verdict methods are introduced base on the above properties. To generate test data, the format of generation protocol packet is fully analyzed. A new approach is given to construct test packet and its efficency is validated by the examples. Finally the summary and the research work in the future are presented.The main creativities of this dissertation are explained as follows:(1) A model of SUT is constructed from nondeterminism in specification and current experience of interoperability testing and a new algorithm of test sequence selection is presented. Interoperability testing involves at least two IUTs (implementation under test) and they make up the SUT. According to the nondeterministic finite state machine of specification and the current experience of interoperability testing, a probability nondeterministic finite state machine(PNFSM) is constructed gradually. The achieved model efficiently describes the current situation of interoperability testing. Based on PNFSM and the certain policy, a binary tree which covers all states of PNFSM is generated. The algorithms, which are used to select test sequences from that binary tree, are presented. The algorithms'validity is proved by an example and the final test sequences are listed in a table. Furthermore the testing scenario of the counting to infinite in RIP is used as an experiment to simply illuminate the modeling method.(2) A new modeling method for interoperability testing is putting forward as well as the test sequence generation method and the test verdict method. A SUT model, called composite Petri net(ComPN), is constructed by two IUTs'Petri nets and a relative complete interactive message sequence. Based on SUT model and protocol specification, the definitions of obligation property, extensible property and interactive property are given. Whereafter based on ComPN and its reachable graph, the algorithms of executable test sequence generation are presented according to each property's definition in the dissertation. Furthermore the definition of property coverage and the test verdict method are putting forwards. BRP(Bounded Retransmission Protocol) is used as an example to show the algorithm's validity. The routing protocols, such as RIP, one of obligation property of OSPF and the policy of BGP4, from different sides show that the modeling method can decrease or avoid state explosion more efficiently than tranditional method when it only focuses on the description of the interested property. Moreover the number of test sequence is reduced dramatically.(3) A method of test data generation, which considers the features of packet, is given to help construct packet automatically. During the process of protocol testing, the consideration of test data should be changed from the granularity of packet to the granularity of field. The general format of packet is analyzed completely. According to their functions and the relation of the values, the fields are divided into three parts, first part is constant part, second part is independent fields and third part is the related fields. Moreover based on the accumulated experience, the priority is assigned to the independent fields and each sequence of related field as a whole. The testing packets are sequentially constructed according to priorities such that the important packets are generated and some aspects of the protocol are tested as early as possible. The tag of priority is used to conduct the verdict of testing result.