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1.1 Introduction
Reliability is a technology that can shorten traffic interruption time and ensure the quality of
service on a network, improving user experience.
1.1.1 Overview of Reliability Technologies
Reliability technologies are used to ensure high reliability on a network. Reliability technologies
cover system and hardware reliability design, software reliability design, reliability testing, and
IP network reliability design.
The reliability of a router involves the following aspects:
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System and hardware reliability design
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Software reliability design
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Test and authentication of reliability
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IP network reliability design
With the popularity of networks and diversification of applications, various value-added services
are deployed on networks. The bandwidth increases in index number. Therefore, even a short-
time interruption may impact a huge number of services critically and make an incredible loss.
For a fundamental network that bears services, its reliability is highlighted much more than ever.
This chapter focuses on reliability technologies applicable to the IP network over the Versatile
Routing Platform (NE80E/40E).
1.1.2 Indices of Reliability
Indices of reliability include MTTR, MTBF, and availability.
Generally, the reliability of a product or a system is evaluated based on two indices, namely,
Mean Time to Repair (MTTR) and Mean Time Between Failures (MTBF).
MTTR
The MTTR indicates the fault recovery capability. It is an index of maintainability. The MTTR
is the average time that a component or a device will take to recover from any failure. The MTTR,
in fact, is the fault-tolerance capability. In a broader sense, the MTTR also includes spare part
management and customer service. The MTTR is usually part of a maintenance contract.
The formula used to calculate the MTTR is as follows:
MTTR = Fault detection time + Board replacement time + System initialization time + Link
recovery time + Route coverage time + Forwarding recovery time
The smaller the addends are, the smaller the MTTR is and the higher the availability a device
offers.
HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
1 Reliability Overview
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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