Reliability and Recovery
260 Avaya Application Solutions IP Telephony Deployment Guide
D: Total System Availability
Total hardware availability is calculated by summing the estimated subsystems’ contributed
downtime.
.
Software Availability Assessment
In order to accurately predict the system availability, software’s overall contribution to downtime
must be considered. Unfortunately, at present, there are no universally accepted
6
industry
standards covering the impact of software to system availability. In order to predict the software
availability with an acceptable level of confidence, thousands of hours of data are collected from
Avaya Communication Manager field performance studies in Early Introduction (EI) trials and
from the in-house Avaya (alpha/beta) trials that precede Avaya external product introductions.
Software failure measurements and analyses are made possible by Avaya Communication
Manager’s event logs, which capture software-induced outages. The sample pool used includes
different versions of Avaya Communication Manager software. The assessment of the data
collected is performed using timestamps from various outage-related software events.
Outages such as server switch reloads and restarts, which interrupt service to all users, are
logged along with the corresponding recovery times. Port network and media gateway reset
logs, along with the time it takes to resume service, are collected and prorated according to the
fraction of impacted users. The outcome of the data analysis puts the availability (uptime) for
the Avaya Communication Manager software application in the range of 99.999% to 99.9999%
(with 90% confidence). For the purpose of projecting the full system availability, the average of
the two numbers (99.9995%) for the software availability value is used.
Data Network Availability
The data network infrastructure is a critical component of an IP Telephony system. A highly
reliable data network involves properly designing the network topology and tuning network
protocols to provide scalability, performance, and fast convergence following a device or link
failure. The availability of IP Telephony services highly depends on the availability of the data
network.
TotalSystemAvailability
1
i
th
SubsystemContributedMinuteDowntime
[
]
i
∑
525960Minutes / Year
------------------------------------------------------------------------------------------------------------------------------------
–
=
6 Telecordia (Bellcore) Generic Requirements for Software Reliability Prediction GR2813-CORE.
Содержание Application Solutions
Страница 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Страница 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Страница 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 74: ...Avaya Application Solutions platforms 74 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Страница 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 214: ...Voice quality network requirements 214 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 239: ...Reliability Issue 3 4 1 June 2005 239 Figure 69 S8700 Media Server in a high reliability configuration ...
Страница 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Страница 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 350: ...Implementing Communication Manager on a data network 350 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Страница 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...