Soonuk Seol

Fully automated interoperability test suite derivation for communication protocols

We propose an automatic test derivation method for testing interoperability of communication protocols. It first derives a skeleton test suite for control part through a sort of reachability analysis. Next, it parameterizes each test case. Finally, it completes the test suite by actualizing test cases by assigning values to their parameters. By constructing test case space based on stable states and by basing test case actualization step on orthogonal arrays used in experimental design techniques, state space explosion is avoided. In order to demonstrate the feasibility and effectiveness, out method is applied to the ATM/B-ISDN signaling protocol and TCP. The application results show that our method surpasses the conventional methods in terms of both test size and coverage.

Interoperability test generation and minimization for communication protocols based on the multiple stimuli principle

This paper presents an automatic test generation and minimization method for testing interoperability of communication protocols such as the asynchronous transfer mode/broadband integrated services digital network (ATM/B-ISDN) signaling protocol and the transmission control protocol (TCP). The method is based on a technique of composing finite-state machines (FSMs). Traditionally, the generation of inputs utilizing FSM was mostly based on sequential test scripting languages and often done manually. Each input is processed on a one-at-a-time basis, which did not allow generating complex scenarios of simultaneous inputs on several interfaces of the system under test (SUT). In practice, there exists the possibility that additional inputs have to be sent to the SUT, while the previous input is still being processed, and/or multiple inputs need to be sent to different interfaces of the SUT at the same time. Our method generates interoperability test cases dealing with these more complex situations. Moreover, it minimizes the number of increased test cases due to the multiple stimuli without jeopardizing transition coverage. Experimental results have shown that compared with the conventional methods, our test generation method generates more interoperability test cases resulting in higher transition coverage (26% higher for TCP and 12% higher for ATM signaling protocol). Also, our test minimization method reduces the interoperability test cases by about 94% in the case of the ATM signaling protocol with the same transition coverage.

Seamless QoS Guarantees in Mobile Internet Using NSIS with Advance Resource Reservation

Providing seamless multimedia services to mobile users is one of the important requirements for the current Internet evolution. However, due to the effects of host mobility, it is difficult to achieve seamless QoS guarantees in mobile Internet. Though Next Step In Signaling (NSIS) protocol was recently proposed as an alternative of RSVP, its applicability has not been completely verified particularly in mobile environment. This paper enhances NSIS protocol based on advance resource reservation using layers 2 and 3 complementation for supporting host mobility. Our approach detects a crossover node (CRN) and reserves network resources proactively along the new path which will be used after handoff This significantly reduces the latency of signaling session re-establishment caused by handoff. Only a few modifications are required to the current NSIS protocol for our approach. The experimental results demonstrate that our approach can provide seamless QoS guarantees for multimedia services in mobile Internet.

Experiments and analysis of voice over Mobile IP

Supporting mobility in real-time applications such as Internet telephony is in demand as the mobile Internet becomes prevalent. A simple solution is to use Mobile JP in order to provide transparent handoffs to upper layer applications. However, due in part to the Mobile IPs limitations such as triangular routing delay and encapsulation overhead, application-layer solutions for mobile Internet telephony has been developed by extending Session Initiation Protocol (SIP). This work presents experimental results on Internet telephony based on Mobile IP and examines its feasibility by analyzing delay factors and increased network toads. We found that packet size in terms of number of frames per packet is important in optimizing the packet transmission delay and network load without hindering the interactivity in voice conversations. Our major contribution is to give a real experience on voice over Mobile IP and to raise a need of designing delay-aware and/or load-aware scheme for Internet telephony.

Interoperability Test Generation for Communication Protocols based on Multiple Stimuli Principle

This paper presents a method for generating interoperability test suites for the class of communication protocols such as the ATM/B-ISDN signaling protocol and TCP that are modeled as communicating nondeterministic finite-state machines. To our knowledge, no test generation method exists for protocol interoperability testing that supports multiple simultaneous inputs to the implementations. In other words, it has been assumed that communicating systems adhere to the single stimulus principle in generating test cases. In practice, however, there exists the possibility that additional messages will be sent to a machine while the previous message is still being processed, and/or simultaneous messages will be sent to several machines at the same time (e.g., TCP’s simultaneous open/close). To cope with these situations, we have developed an interoperability test suite derivation algorithm based on formal models. Experimental results show that our method is applicable to practical systems and can generate validation-equivalent interoperability test suites in terms of transition coverage.

Interoperability Test Suite Generation for the TCP Data Part Using Experimental Design Techniques

Test derivation methods suitable for interoperability testing of communication protocols were proposed in [1,2, 3] and applied to the TCP and the ATM protocols, The test cases that were generated by them deal with only the control part of the protocols. However, in real protocol testing, the test cases must manage the data part as well. For complete testing, in principle we must test all possible values of data part although it is impractical to do so. In this paper, we present a method generating the interoperability test suite for both the data part and the control part of protocols with the example of Tep connection establishment. In this process, we make use of experimental design techniques from industrial engineering to minimize the size of test suite while keeping testing capability. Experimental design techniques have been used for protocol confom1ance testing but not for intcruperability testing so far. We generate the test suite for data part by this method and show a possibility that we can test interoperability of protocols with the minimum number of test cases while maintaining the testing power.

Interoperability Test Suite Derivation for the TCP

A test derivation method suitable for testing interoperability for the class of communication protocols like the ATMB-ISDN signaling protocol was proposed in [KanK 97]. Up to now, there is no work implementing automatic derivation of the interoperability test suite in the method and analyzing its coverage. In this paper, we implement the algorithm proposed in [KanK 97], apply it to the ATMB-ISDN signaling protocol and the TCP protocol, and analyze the application results. In this process, we (1) improve the algorithm so that it can handle features like the TCP’s three-way handshaking, (2) implement the improved algorithm as a program and derive an interoperability test suite automatically as a result of applying it to a pair of communicating TCP FSMs, and (3) analyze the generated interoperability test suite in terms of transition coverage1.

Distributed Test using Logical Clock

It is difficult to test a distributed system because of the task of controlling concurrent events. Existing works do not propose the test sequence generation algorithm in a formal way and the amount of message is large due to synchronization. In this paper, we propose a formal test sequence generation algorithm using logical clock to control concurrent events. It can solve the control-observation problem and makes the test results reproducible. It also provides a generic solution such that the algorithm can be used for any possible communication paradigm. In distributed test, the number of channels among the testers increases non-linearly with the number of distributed objects. We propose a new remote test architecture for solving this problem. SDL Tool is used to verify the correctness of the proposed algorithm, and it is applied to the message exchange for the establishment of Q.2971 point-to-multipoint call/connection as a case study.