Automatic Testing of Neighbor Discovery Protocol Based on FSM and TTCN

1. APCC’2004 Automatic Testing of Neighbor Discovery Protocol Based on FSM and TTCN Sep. 1, 2004 Zhiliang Wang, Xia Yin, Haibin Wang, Jianping Wu Department of Computer Science Tsinghua University http://netlab.cs.tsinghua.edu.cn

2. Outline • Background • Motivation • Our proposed method • Conclusion and Future work APCC'2004

3. Background: Protocol Conformance Testing Protocol Specification Test Generation Implementation Process Abstract Test Suite Protocol Impl. IUT Test Implementation Test Execution Test Verdict APCC'2004

4. Background: Neighbor Discovery Protocol • One of the basic protocols in IPv6 protocol set • Should be supported in all IPv6 implementations • Corresponding functions in IPv4 • ARP (Address Resolution Protocol) • ICMP router discovery • ICMP redirect function • Using 5 ICMP packet types: • Router Solicitation • Router Advertisement • Neighbor Solicitation • Neighbor Advertisement • Redirect APCC'2004

5. Background: Related work • Conformance testing of ND Protocol • InterOperability Laboratory, University of New Hampshire • TAHI Project • Institute of Computing Technology, Chinese Academy of Sciences • Existing Problems • No standard language used to specify test suite • Must be executed on the proprietary test systems • Not guided by formal methods • Cannot ensure test coverage and reliability of test suite APCC'2004

6. Protocol Specification Test Generation Implementation Processes Abstract Test Suite Protocol Impl. IUT Test Implementation Test Execution Test Verdict Background: Our method • FSM • Finite State Machine • To specify protocol specification • TTCN-2 • Tree and Tabular Notations • Test case specification language • PITS • Our previous work • Protocol Integrated Test System • TTCN-based test system • Automatic test process • Test practice FSM TTCN PITS APCC'2004

7. Outline • Background • Motivation • Our proposed method • Conclusion and Future work APCC'2004

8. Motivation • Protocol Modeling • Control part • Data part • Timed part • ND Protocol includes simple Timer Operations! • How to specify it? • EFSM? (Extended FSM) • Control part and data part, no timer! • TIOA? (Timed Input Output Automata) • Common model for timed system • Test generation process has tremendous costs on time and space • Difficult to be applied in practical conformance testing • Our method: EFSM + simple timer operations APCC'2004

9. Outline • Background • Motivation • Our proposed method • Formal Model • Test Architecture • Test Generation • Test Practice • Test Results and Analysis • Conclusion and Future work APCC'2004

10. Formal Model • EFSM with Simple Timed Extensions • EFSM + simple timer operations • A local timer for each state • Transition of such a model: • tact (timed action): invoke the local timer start(tq) • Timeout transition:input is timeout(ts) t5 INCOMPLETE REACHABLE up: variable update function i: Input P: Predicate t3 t3: timeout(TI)[counter=3]/{counter:=0} o: output t5: ?NA[NA.S=1]/{LLA:=NA.TLLA;start(TR)}!ERep NONE i: Input P: Predicate up: variable update function tact: timed action APCC'2004

11. Formal Model (cont) Protocol specification of Neighbor Unreachability Detection in ND Protocol States: 6 Transitions: 45 APCC'2004

12. Formal Model (cont) Protocol specification of Neighbor Unreachability Detection in ND Protocol APCC'2004

13. Formal Model (cont) • External Observable timed features • Do not apply any external inputs to the machine in state s. If an external output o can be observed after waiting a while, state s has an External Observable Timed Feature and its observed output is o. • the external behaviors of timeout transitions • To verify the transient state • Example APCC'2004

14. Test Architecture PCO: Point of Control and Observation IUT: Implementation Under Test APCC'2004

15. Test Generation • Conformance test suite • State cover: for each state S • Transition cover: for each transition t State to be tested r pre(S) ds(S) ? ? S0 S State cover test case Lead the machine to the initial state S0 Lead the machine from S0 to state S Verify the final state is S r ds(Q) pre(S) t ? Transition cover test case ? S0 S Q r: Reset pre(S):Preamble Verify the final state is Q Transition to be tested ds(S):Distinguishing Sequence APCC'2004

16. Test Generation (cont) • Generation of Distinguishing Sequence • Extension of traditional method • Key idea: Consider Timed Features of model {N,I,S,R,D,P} Example: Wait Distinguishing Seq. of state S: mNS (1s) -- uNS (1s) uNS (5s) Wait/--; ?EReq/!EPep; Wait(5s)/!uNS I D {N,S,R} P EReq mNS ERep N {S,R} Wait uNS (5s) -- S R APCC'2004

17. Test Generation (cont) • TTCN-2 Test case example: APCC'2004

18. Test Generation (cont) APCC'2004

19. Test Practice • Test System RI: Reference Implementation PCO: Point of Control and Observation IUT: Implementation Under Test APCC'2004

20. Test Practice (cont) • RI (Reference Implementation) APCC'2004

21. Test Results and Analysis • Overview of NDP test suite • Test Result APCC'2004

22. Conclusion and Future work • A formal method to test neighbor discovery protocol • Protocol specification: FSM-based method • Test generation • Test specification: TTCN-2 • Test practice: PITS • Future work: • Data flow testing for such a model • further test activities on IPv6 protocols, especially routing protocols APCC'2004

23. Thank you!Q&A