Understanding Network Equipment Reliability

Abstract

This paper reviews the concepts and techniques that have been adopted by BT in order to understand network equipment reliability. The ideas presented are largely generic, in the sense that they can be applied irrespective of whether the equipment is intended for a core network or an access network application. In particular, the paper examines the relationship between out-turn reliability and the reliability that might be guaranteed by an equipment manufacturer. The relevance of confidence limits to reliability modelling and in-service reliability monitoring is also discussed, and ideas presented on how reliability monitoring can be applied to resilient networks. It is shown that in competitive situations, there are good reasons why reliability modellers should use failure rate data whose upper confidence limit is 50%. In contrast, it is shown that for practical reasons, in-service monitoring schemes should not be based on specific confidence levels.

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References

  1. 1

    Mellis J et al: ‘Performance and reliability requirements for passive components in local optical networks’, Proceedings of the 12th Annual Conference on European Fibre Optic Communications and Networks (1994).

  2. 2

    ‘Handbook of Reliability Data’, Issue 5 (HRD5) (1994).

  3. 3

    Johnston C: ‘System reliability prediction’, BT private communication (March 1986).

  4. 4

    Skrimshire C: ‘Alternative ways of expressing reliability and performance targets’, BT private communication (March 1995).

  5. 5

    Shaw R: ‘System reliability model, type T1.4’, Internal BT spreadsheet (1998).

  6. 6

    IEC Standard 605-7: ‘Equipment reliability testing – compliance test plans for failure rate and mean time between failures assuming constant failure rate’, Issue 1 (1978).

  7. 7

    Shaw R: ‘System reliability analysis of duplicated subsystems’, BT private communication (June 1993).

  8. 8

    Smith D: ‘Reliability and maintainability in perspective’, The Macmillan Press (1981).

  9. 9

    O'Connor P: ‘Practical reliability engineering’, Second edition, John Wiley and Sons (1985).

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Ford, D.J. Understanding Network Equipment Reliability. BT Technology Journal 16, 180–186 (1998). https://doi.org/10.1023/A:1009616418109

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Keywords

  • User Interface
  • Failure Rate
  • Confidence Limit
  • Practical Reason
  • Access Network