Resource sizing
Issue 3.4.1 June 2005
175
Processing occupancy
The Busy Hour Call Attempt (BHCA) rate of a system is the total number of calls that are
attempted within that system, during its busy hour. This is distinct from the Busy Hour Call
Completion (BHCC) rate of a system, which counts only those calls that have actually been
completed. The call capacity of a system refers to its BHCC rate.
In Communication Manager products, server occupancy (or processor occupancy, as
applicable) can be broken down into three categories: static occupancy, Call Processing (CP)
occupancy, and system management (SM) occupancy. The static component refers to
keep-alive processes, the CP component refers to processes that are required to set up and
tear down calls (as well as vectoring operations, in the case of call centers), and the SM
component refers to background maintenance operations and system audits. In theory, static
occupancy is a fixed overhead, and CP occupancy is directly proportional to the call rate. SM
occupancy is allocated on an as-needed basis, such as for periodic maintenance functions.
However, if the overall server occupancy exceeds a particular threshold, SM operations are
postponed until a quieter traffic period.
Usually, the relationship between the sum of static and CP occupancy, as a function of BHCC, is
linear, with a positive y-intercept, as illustrated in
Figure 60: Relationship Between Processing
Occupancy and BHCC Rate
. The slope of the line corresponds to the average processing cost
per call, and the intercept corresponds to the idle (that is, no-load) occupancy. The average
processing cost per call depends on the mix of calls that is being handled by the system, and
how complex each type of call is. For general business calls, nearly all of the CP occupancy is
associated with setting up and tearing down calls. The call processing that is required for
maintaining the call once it has been established is negligible in comparison, regardless of how
long the call lasts. In a call center, the additional cost of processing vectoring steps throughout
the lifetime of a call must also be considered.
Figure 60: Relationship Between Processing Occupancy and BHCC Rate
Proc
essing O
ccup
a
nc
y
(CP
+
S
tat
ic)
BHCC Rate
Idle (No-Load)
Occupancy
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 ...