Reliability and Recovery
258 Avaya Application Solutions IP Telephony Deployment Guide
B. Markov State Modeling for Redundant Components
For measuring the failure rate of the components that are working in parallel, either in active/
standby mode or active/active mode, the Markov Chain Model is used.
5
The state-transition
diagram of the Markov model displays the possible combinations of "up" and "down" states for
each component. Evaluation of the model along with the failure rates and repair/recovery rate
leads to the estimation of the individual steady-state probabilities and failure rates.
Example: - Consider an Avaya solution that features duplex Avaya S8700 Media Servers,
which are operating in an active/standby mode. The corresponding Markov state-transition
diagram is presented in
Figure 74
.
Figure 74: Markov State Transition Diagram for Duplicated Server
In
Figure 74
, State 2 represents both servers operating while State 1 represents one server
operating and State 0 represents no operating servers. The parameter
λ
represents the average
failure rate expressed in failures per hour of individual server, and it is the reciprocal of MTBF (
λ
= 1/MTBF). The parameter
µ
represents the average repair rate, expressed in repairs per hour
of an individual server, and it is the reciprocal of MTTR (
µ
= 1/MTTR). A critical outage only
occurs when both servers are down, and thus the failure arrival rate for the pair of servers as a
whole is the rate at which transition from "State 1" to "State 0" occurs. The failure rate is
calculated according to the following formula:
P1 is the probability of being in "State 1".
5 This Model is also known as the State-Space Model.
2
1
0
2
λ
λ
µ
2
µ
F
λ
P
1
×
=
P
1
2
λ
×
µ
×
µ
2
2
+
λ µ λ
2
+
×
×
----------------------------------------------
=
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 ...