Network Protocol Testing Technology

In the development of computer networks, protocols have always been at the core. From the development of ARPAnet to the Internet, the key link is to form an international standard protocol. Protocols are a set of rules that must be followed for information exchange between various communication entities in computer networks and distributed systems. They are like a syntax rule and the cornerstone of network construction.

In 1984, ISO proposed an ISO/OSI reference model for Open System Interconnection.

In January 1, 1983, TCP/IP was announced as the only formal protocol on the Internet, paving the way for the development of the Internet.

The most significant achievement of network communication protocol research was that in 1980s, formal technology and software engineering methods were applied to Protocol research, forming a new discipline-Protocol engineering, which covers the following areas: protocolSpecification, ProtocolValidation, ProtocolVerification, ProtocolSynthesis, ProtocolConversion, and ProtocolPerformanceAnalysis) protocolAutomaticImplementation and ProtocolTesting ).

Next we will focus on the role and significance of protocol testing, introduce the achievements in this field, and point out the challenges faced by protocol testing.

Significant

The rise in the field of protocol testing research stems from the essential demand for it. Currently, network protocols are mostly text described in natural languages. Different understandings of protocol texts and non-formal factors in the implementation process lead to different protocol implementations, sometimes even incorrect protocol implementation. Even if the protocol is correctly implemented, different implementations cannot communicate with each other accurately, and the performance of different implementations of the same Protocol is also different. In this case, an effective method is required to evaluate the protocol implementation, which is "protocol test ".

With the popularization of computer networks and the increasing demand for networks, computer network protocols are becoming more and more complex. Protocol implementation not only requires correct functions and intercommunication, but also requires good performance, therefore, protocol implementation and development become more and more complex. Protocol testing is a necessary and important means to ensure quality. Currently, protocol testing is not only a simple detection support process in the product development and development process, but also an important branch of computer network technology. The Research on protocol testing technology will directly affect the progress of computer network technology and the competition and development of the world's network market. Therefore, many countries have invested a lot of manpower and material resources in protocol testing research. For example: NPL, French National Communication Research Center, GMD of the German National Communication Research Bureau, the United States National Standardization Research Institute, the United States University of New York interoperability Research Laboratory, China Tsinghua University Department of Computer Science and Technology computer Networks, protocol testing laboratories, and other units have invested a lot of research efforts in this field.

Research methods

Protocol testing is developed on the basis of software testing. According to the control observation method of the tested software, the software testing methods are divided into three types: white box testing, black box testing and gray box testing. The white-box test fully checks the entire program code by executing each statement at least once, while the black-box test only tests the behaviors that can be observed outside the software, without involving the internal structure of the program. White box testing has a strong testing capability, but the process is too complex and has high requirements on the tested software. Black box testing only cares about the input and output of the tested software. Although the testing capability is weaker, the testing process is relatively simple and there are no special requirements for the tested software. The gray-box test is a testing method that combines the white-box test and the black-box test, absorbing the advantages of the two methods.

Protocol testing is a black box testing. It evaluates the external behaviors of the protocols under test by observing the protocol. Currently, protocol tests are divided into three aspects: ConformanceTesting, InteroperabilityTesting, and PerformanceTesting ). The consistency test mainly tests whether the implementation of the Protocol strictly follows the corresponding protocol description. The interoperability test focuses on the interconnectivity between the implementation of different protocols under the same protocol standard. Performance testing uses experimental methods to observe various performance parameters implemented by the tested protocol, such as throughput and transmission latency. The results are often related to the input load.

In the above three aspects, the consistency test was launched at the earliest stage, and many valuable results were also formed. ISO International Standard ISO-"OSI protocol consistency testing methods and framework ", the process, concepts, and methods of protocol testing based on the OSI Layer-7 reference model are described in natural language. However, with the continuous development of computer network technology, new protocols become more and more complex, and protocol consistency testing has encountered many difficulties. In this process, a large number of formal methods were introduced into the field of protocol testing. In 1995, ISO introduced the international standard "formal methods in consistency testing" to describe the formal methods used in each phase of the protocol consistency testing process. However, due to the complexity of protocol consistency testing, the standard remains in the draft phase. The Research Technology of interoperability testing is basically inherited from consistency testing. As the demand for network applications increases rapidly, network performance has become equally important to functions. Research on protocol performance testing is also underway. While conducting a lot of testing practices, theoretical research is also starting.

Consensus reached

At present, the international protocol testing research field has achieved the following two consensus:

First,The protocol consistency test process is streamlined.

Second,The formal technology is introduced into the protocol testing field, and the concept and method of protocol testing are studied in a clear and unambiguous manner using strict mathematical language. However, it is also found that there are many shortcomings in this method, the most obvious of which is that there is still a huge gap between these theoretical studies and practical applications.

Achievements and Prospects

Since 1989, the Department of Computer Science and Technology of Tsinghua University, under the guidance of Professor Wu Jianping, has been insisting on in-depth exploration and research on protocol testing, the plan was funded by various national departments and undertaken the task of developing a protocol conformance testing system, the protocol consistency test system PCTS (ProtocolConformanceTestingSystem), which can be used to test the protocols in the OSI Layer-7 reference model, is developed successfully ). During the Ninth Five-Year Plan period, based on the successful test of the communication protocol of the OSI reference model, the ProtocolIntegratedTestingSystem (PITS) was developed and developed, with the goal of under the guidance of the formal theory, develop a universal testing platform. Any protocol can be tested as long as it is described using a unified testing notation.

In the development process of PITS, there are many aspects that are quite successful. For example, on the basis of PCTS, PITS can be formed through slight optimization and improvement, so that consistency tests can be conducted on TCP/IP communication protocol and Frame Relay protocol, some preliminary interoperability tests and performance tests can also be carried out on this platform.

PITS has made gratifying achievements. It not only plays an important role in the development of the core router in China's "863" project, in addition, many academic achievements were published at important international conferences in the form of papers, which were recognized by scholars and experts from international counterparts.

Today, protocol testing is facing more severe challenges than ever before. The development of protocols is comprehensive, not only increasing in functions, but also from a single communication protocol to a more complex routing protocol. In the face of protocols from the ISO Reference Model to the TCP/IP series, from X.25, frame relay to the ATM protocol, and even more complex routing protocols such as RIP, OSPF, and BGP ), protocol tests must also evolve from a single functional test to multi-faceted tests, including functions that can be described by traditional finite state machines and data with complex structures. Therefore, there are many open and inconclusive problems in the protocol testing field, which deserves further research.

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