Schneider, F., "A Paradigm for Reliable Clock Synchronization", Technical Report TR 86-735, Cornell University, February 1986.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....message even several consecutive ones could be affected, the resulting receive omissions cannot be attributed to the innocent sending nodes. Another example are receiver caused timing failures in applications that disseminate time dependent information, as in clock synchronization [20, 17]. Since the received information varies with the experienced end to end transmission delay here, excessive delays can easily produce incorrect even inconsistent, i.e. Byzantine information at the receiving end(s) The major sources of excessive delays, however, are network controller ....

F. B. Schneider. A paradigm for reliable clock synchronization. In Proceedings Advanced Seminar of Local Area Networks, pages 85--104, Bandol, France, Apr. 1986.

....message even several consecutive ones could be affected, the resulting receive omissions cannot be attributed to the innocent sending nodes. Another example are receiver caused timing failures in applications that disseminate time dependent information, as in clock synchronization [22, 19]. Since the received information varies with the experienced end to end transmission delay here, excessive delays can easily produce incorrect even inconsistent, i.e. Byzantine information at the receiving end(s) The major sources of excessive delays, however, are network controller ....

F. B. Schneider. A paradigm for reliable clock synchronization. In Proceedings Advanced Seminar of Local Area Networks, pages 85--104, Bandol, France, Apr. 1986.

....respect to our system, this would comprise submitting multiple copies of reputation statements. Signatures themselves provide only content authenticity and integrity; our approach was to include timestamps creating the notion of statement freshness. Secure clock related issues are addressed in [16, 3]. 4 Deploying XenoTrust This section considers the deployment of the XenoTrust service and relevant parts of the two services it co operates with: XenoSearch and XenoStore. Statement advertisements Reputation statements are stored in XenoStore through XIS; for every new participant in the ....

F. B. Schneider. A paradigm for reliable clock synchronization. Technical Report TR86-735, 1986.

....the exposition above, it maintains bounded precision when started from an initially synchronized state and takes care of accuracy intervals as well. However, the algorithm is generic in the sense that the convergence function employed for computing the clock adjustments is left unspecified. As in [Sch86] all results (worst case precision, accuracy, maximum adjustment, etc. are hence expressed in terms of a few characteristic parameters of the convergence function. In order to determine the performance of a particular instance of the algorithm, all that needs to be done is to evaluate the ....

Fred B. Schneider. A paradigm for reliable clock synchronization. In Proc. Advanced Seminar of Local Area Networks, pages 85--104, Bandol, France, April 1986.

.... Gamma C j (t)j ffl external synchronization with accuracy ff Sufficiently many R i (t) correct ) jC i (t) Gamma tj ff High Accuracy Time Services WG10.4 Winter Meeting 2000 12 Clock Synchronization Algorithms Many different algorithms exist, but can be explained by a generic principle [Sch86]: 1. Generate (approximately) simultaneous event at all nodes ffl exploit synch. clocks: LWL88] FC97b] SynUTC ffl generate event via messages: ST87] VRC97] 2. Read remote clocks values ffl one way: LWL88] SynUTC ffl round trip: Cri89] 3. Compute convergence function ffl ....

Fred B. Schneider. A paradigm for reliable clock synchronization. In Proceedings Advanced Seminar of Local Area Networks, pages 85--104, Bandol, France, April 1986.

....algorithms, a clock knows at any time if it is synchronized or not with the others, whereas in statistical algorithms, clocks do not know how far apart they are from each others. Clock synchronization has been extensively studied for the last twenty years. Thorough surveys can be found in [Sch86, RSB90] and [SWL90] In [RSB90] software and hardware clock synchronization algorithms are classified with regard to the clock correction scheme used. In contrast, the algorithms surveyed in [SWL90] are listed according to the supported faults and the system synchrony (i.e. knowledge of upper bounds on ....

....clock synchronization algorithms are classified with regard to the clock correction scheme used. In contrast, the algorithms surveyed in [SWL90] are listed according to the supported faults and the system synchrony (i.e. knowledge of upper bounds on communication latencies) Schneider s work [Sch86] gives a single unifying paradigm and correctness proof that can be used to understand mostly all deterministic clock synchronization algorithms supporting Byzantine failures. Our work extends these surveys by proposing a taxonomy adapted to all published software fault tolerant clock ....

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F. Schneider. A paradigm for reliable clock synchronization. Technical Report TR86-735, Computer Science Department, Cornell University, February 1986.

....applications, such as causal relationships [Lam78] In addition, we do not detail issues speci c to clock synchronization in large scale distributed systems (e.g. SR87, VCR97] Clock synchronization has been extensively studied for the last twenty years. Thorough surveys can be found in [Sch86, RSB90] and [SWL90] In [RSB90] software and hardware clock synchronization algorithms are classi ed with regard to the clock correction scheme used. In contrast, the algorithms surveyed in [SWL90] are listed according to the supported faults and the system synchrony (knowledge of upper bounds on ....

....hardware clock synchronization algorithms are classi ed with regard to the clock correction scheme used. In contrast, the algorithms surveyed in [SWL90] are listed according to the supported faults and the system synchrony (knowledge of upper bounds on communication latencies) Schneider s work [Sch86] gives a single unifying paradigm and correctness proof that can be used to understand mostly all deterministic clock synchronization algorithms supporting Byzantine failures. Our work extends these surveys by proposing a taxonomy adapted to all published software clock synchronization algorithms: ....

[Article contains additional citation context not shown here]

F. B. Schneider. A paradigm for reliable clock synchronization. Technical Report TR86-735, Computer Science Department, Cornell University, February 1986.

....with deterministic ones. In [7] the problem of synchronizing n clocks in a fully connected network is considered. Even if the clocks run at the same rate of real time and there are no failures, it is impossible to synchronize clocks closer than (1 Gamma 1 n ) where = max Gamma min. In [2] clock synchronization is achieved using a convergence function CF that ensures fault tolerance. The assumptions are that there is an initial synchronization of clocks and that all non faulty clocks are correct. The precision achieved is max Gamma min. In [3] the upper bound used for ....

Schneider F. B. "A paradigm for reliable clock synchronization" Cornell University Ithaca N.Y., February 1986, TR 86-735.

.... as UTC (Universal Time Coordinates) or GPS (Global Positioning System) A number of deterministic clock synchronization algorithms has been published [4, 8, 10, 14] Most of them are structured around periodic rounds of broadcast communication and address fault tolerance aspects; for a survey see [13]. An important result [11] fixes the upper bound ffi = max Gamma min) 1 Gamma 1=N) on Universit e Catholique de Louvain y Universit a degli Studi di Pisa the synchronization precision for deterministic algorithms executing in a distributed system with N nodes. Here min and max are the ....

F.B. Schneider. A paradigm for reliable clock synchronization. Technical Report TR 86-735, Cornell University, Ithaca, NY, 1986.

....the resynchronization information is placed on the transmitter only when the access to the bus is granted. If the application requires a high degree of reliability, we can arrange to tolerate the failure of one or more time measuring devices: a survey of the work done on this subject is in [15], and the implementation referred above also ensures a high reliability. Ring architectures are also applicable to implement a bus based global timing system, as illustrated in [8] But bus based approaches are of limited scope, since the timing imprecision is bound to the lengh of the bus and to ....

....presence of a set of units that hold clocks that evaluate the present time in approximately the same way. The values of the clocks of the units in R (here after called reference units) fall within an interval spanning ref : this is the property usually associated with a set of accurate clocks [15]. In addition, the bound drift property always holds for a reference unit and the units know whether they are members of the set of references or not: we assume that the set of references is statically predetermined, and therefore the answer to the AmIRef procedure is hardwired into each unit. ....

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Schneider F. B. "A Paradigm for Reliable Clock Synchronization ", Technical Report of Cornell University Ithaca N.Y.; February 1986; TR 86-735.

....failure handling, redundancy preservation and scheduling. Achievement of replica determinism depends on the system architecture and the implementation of server objects. The requirements for deterministic behavior of servers are most commonly decomposed into the following basic abstractions [Schneider, 1986, Cristian, 1991] i) Membership: Every non faulty client has timely and consistent information on the set of functioning servers objects which constitutes a group. This information can be hidden behind the abstraction of the communication service. ii) Agreement: Every non faulty server in a ....

Schneider, F. B. (1986) A Paradigm for Reliable Clock Synchronization. Proc. Advanced Seminar Real-Time Local Area Networks, (pp. 85104) .

....[13] This paper provides description and analysis of a simple interval based algorithm suitable for being used in clock validation, which is generic w.r.t. the convergence function employed. Thus, our results are given in terms of some characteristic parameters of the convergence function, cf. [15]. In order to determine precision and accuracy of a particular instance of our algorithm, it only remains to determine the characteristic parameters of the particular convergence function, and to plug them into the generic results. Lacking space prohibited us from including a sample analysis in ....

F. B. Schneider. A Paradigm for Reliable Clock Synchronization, Proc. Advanced Seminar of Local Area Networks, Bandol, France, April 1986, p. 85--104.

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Schneider, F., "A Paradigm for Reliable Clock Synchronization", Technical Report TR 86-735, Cornell University, February 1986.

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Fred B. Schneider. A paradigm for reliable clock synchronization. In Proc. Advanced Seminar of Local Area Networks, pages 85--104, Bandol, France, April 1986.

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