Formally verified Byzantine agreement in presence of link faults

U. Schmid1, B. Weiss1, J. Rushby2
1Department of Automation, Technische Universität Wien, Vienna, Austria
2Computer Science Laboratory, SRI International, Inc., Menlo Park, CA, USA

Tóm tắt

This paper shows that deterministic consensus in synchronous distributed systems with link faults is possible, despite the impossibility result of Gray (1978). Instead of using randomization, we overcome this impossibility by moderately restricting the inconsistency that link faults may cause system-wide. Relying upon a novel hybrid fault model that provides different classes of faults for both nodes and links, we provide a formally verified proof that the m+1-round Byzantine agreement algorithm OMH (Lincoln and Rushby (1993)) requires n > 2f/sub l//sup s/ + f/sub l//sup r/ + f/sub l//sup ra/ + 2(f/sub a/ + f/sub s/) + f/sub o/ + f/sub m/ + m nodes for transparently masking at most f/sub l//sup s/ broadcast and f/sub l//sup r/ receive link faults (including at most f/sub l//sup ra/ arbitrary ones) per node in each round, in addition to at most f/sub a/, f/sub s/, f/sub o/, f/sub m/ arbitrary, symmetric, omission, and manifest node faults, provided that m /spl ges/ f/sub a/ + f/sub o/ + 1. Our approach to modeling link faults is justified by a number of theoretical results, which include tight lower bounds for the required number of nodes and an analysis of the assumption coverage in systems where links fail independently with some probability p.

Từ khóa

#Algorithm design and analysis #Formal verification #Fault tolerant systems #Automation #Computer science #Laboratories #Broadcasting #Failure analysis #Distributed algorithms #Field buses

Tài liệu tham khảo

10.1145/357172.357176 10.1007/3-540-56922-7_24 10.1109/FTCS.1993.627343 lynch, 1996, Distributed Algorithms meyer, 1987, Consensus with dual failure modes, Digest of Papers International Symposium on Fault-Tolerant Computing, 48 owre, 1996, PVS: Combining specification, proof checking, and model checking, Computer-Aided Verification CAV'96, 411, 10.1007/3-540-61474-5_91 10.1109/TSE.1986.6312888 pinter, 1985, Distributed agreement in the presence of communication and process failures, Proceedings of the 14th IEEE Convention of Electrical & Electronics Engineers in Israel 10.1145/197917.198115 rushby, 2001, Formal verification of hybrid Byzantine agreement under link faults, Technical re-port Computer Science Laboratory SRI Inter-national biely, 2001, Message-efficient consensus in presence of hybrid node and link faults, Technical Report 183, 1 walter, 2000, The customizable fault/error model for dependable distributed systems, Theoretical Computer Science basu, 1996, Simulating reliable links with unreliable links in the presence of process crashes, Proc 10th Workshop Distributed Algorithms (WDAG), 105, 10.1007/3-540-61769-8_8 10.1007/BF01843568 10.1145/42282.42283 gray, 1978, Notes on data base operating systems, Operating Systems An Advanced Course, 465 gong, 1995, Byzantine agreement with authentication: Observations and applications in tolerating hybrid and link faults, Proceedings of Dependable Computing for Critical Applications, 139 10.1109/12.888039 hadzilacos, 1993, Fault-tolerant broadcasts and related problems, Distributed Systems, 97 attiya, 1998, Distributed Computing 10.1007/s004460050016 10.1109/DSN.2001.941391 schmid, 2000, Orthogonal accuracy clock synchronization, Chicago Journal of Theoretical Computer Science, 2000, 3 schmid, 2001, Consensus with oral/written mes-sages: Link faults revisited, Technical Report 183, 1 10.1007/PL00008927 10.1109/RELDIS.1988.25784 10.1109/71.667895