Design for High Availability
Issue 3.4.1 June 2005
257
The data required for predicting system availability is limited to unplanned outage frequency
and downtime experienced by service interruption. Potential outages are defined as follows:
●
A Reportable Outage: "A reportable outage is an event that includes total loss of
origination and termination capability in all switch terminations for greater than 30 seconds
period (uninterrupted duration)."
●
Outage Downtime Measure: "An outage downtime Performance Measure is the
expected long-term average sum, over one operating year, of the time durations of events
that prevent a user from requesting or receiving services. A failure that causes service
interruption contributes to the outage downtime of that service. Outage downtime is
usually expressed in terms of minutes of outage per year."
●
Downtime Measure for Partial Outages: "The downtime measure for Partial Outage
Events is a Weighted Downtime Performance Measure. The actual time duration of a
partial outage is weighted by the fraction of switch terminations affected by the outage
condition."
The following criteria are also considered when assessing system availability:
●
* Only unplanned downtime will count against availability of the system/switch. For
example, if software upgrades require service interruption, the downtime associated with
firmware and software upgrades is considered to be "planned," and by definition, will not
count against the availability of the system.
●
* Outages of the enterprise’s IP data network and failure of non-Avaya products will not
count against the availability score for the Avaya furnished solution components
(products).
●
* Downtime due to operator error will not count against system availability.
Hardware Availability Assessment
The hardware availability prediction follows the following steps
A. MTBF and FIT data
The MTBF (Mean Time Between Failure) and FIT (Failure in Time Rate) data of individual
components are estimated based on Telecordia recommended "Part Count Method". This
process consists of summing the failure rates of all devices comprising the module.
4
When
extended field performance data of the module is available, typically based upon a review of two
(2) years of marketplace performance in a variety of settings for numerous enterprises, a more
accurate MTBF can be estimated.
4 Telecordia (Bellcore) GR-512, Requirement R3-1, Hardware Reliability Modeling Methods, Section 3.1, Method
I of Reliability Prediction Procedure for Electronic Equipment (RPP).
Summary of Contents for Application Solutions
Page 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Page 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Page 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Page 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Page 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Page 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...