Cisco Unified Contact Center Enterprise Solution Reference ...

Cluster Sizing Concepts
10-2
Cisco Unified Contact Center Enterprise 7.x SRND
Chapter 10 Sizing Cisco Unified CallManager 4.x and 5.x Servers
Once you have completed these tasks, you can begin to accurately size the necessary Cisco Unified
CallManager cluster(s). Many factors impact the sizing of a Cisco Unified CallManager cluster, and the
following list mentions some of those factors:
Number of office phones and the busy hour call attempt (BHCA) rate per phone
Number of inbound agent phones and the BHCA rate per phone
Number of CTI ports and the BHCA rate on those VoIP endpoints (can be zero if CVP is used for
call treatment, self service, and queueing)
Number of voice gateway ports and the BHCA rate on those VoIP endpoints
Number of outbound agent phones, outbound dialing mode, and BHCA rate per phone
The number of outbound dialer ports, number of IVR ports for outbound campaigns, and the BHCA
rate per port for both
The number of mobile agents and the BHCA rate per mobile agent
Number of voicemail ports and the BHCA rate to those VoIP endpoints
Signaling protocol(s) used by the VoIP endpoints
Percent of agent call transfers and conferences
Dial plan size and complexity, including the number of dialed numbers, lines, partitions, calling
search spaces, locations, regions, route patterns, translations, route groups, hunt groups, pickup
groups, route lists, and so forth
Amount of media resources needed for functions such as transcoding, conferences, encryption, and
so forth
Co-resident applications and services such Auto Attendant, CTI Manager, E-911, and Music On
Hold
Cisco Unified CallManager release (sizing will vary per release)
Desired hardware server model (sizing will vary per hardware server model)
Other factors can affect cluster sizing, but the above list shows the most significant factors in terms of
resource consumption.
The general process to sizing a Cisco Unified CallManager cluster is to estimate the resource
consumption (CPU, memory, and I/O) for each of these factors and then to choose hardware that will
satisfy the resource requirements.
It is important to gather information with regards to the factors listed above before attempting to size a
cluster with any accuracy. To assist in calculating these numbers that relate to Unified CCE, Cisco
recommends using the Unified CCE Resource Calculators, discussed in the chapter on Sizing Call
Center Resources, page 8-1.
In prior releases of the Cisco Unified CallManager software, Cisco utilized various schemes to calculate
the capacity of a cluster using device weights, BHCA multipliers, and dial-plan weights. With Cisco
Unified CallManager Releases 4.x, 5.x, and later, these approaches have been replaced by the Cisco
Unified CallManager Capacity Tool to allow for more accurate planning of the system. The next section
describes the Cisco Unified CallManager Capacity Tool.
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