Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

This document provides answers to questions that are frequently asked in regard to the Unified Communications Sizing Tool (Unified Communications ST) available at the following URL:http://tools.cisco.com/cucstThis document includes the following questions:

About the Unified Communications ST

1. Who can access the Unified Communications Sizing Tool?2. What products and versions does the Unified Communications ST support?3. How do I learn how to use the Unified Communications ST?4. How is Unified Communications ST better than Cisco Unified Communications Manager Capacity

Tool?

5. Can I use the output of Unified Communications ST to enter information into the Unified CMCT?6. Can I use the output of Unified Communications ST to enter information into the Unified CCE

Sizing Tool?7. Why cant Unified CM be sized as an individual component?8. How can I size a system based on Unified CM 4.x?9. Can anyone use Unified Communications ST?

10. How do I install the Unified Communications ST?11. What browser can I use to access the Unified Communications ST?12. How do I save my sizing solution for later reference?13. How do I download a solution sizing summary report?14. What are the Internet Explorer browser settings required to revalidate old solutions for new Unified Americas Headquarters:

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Communications ST releases, download a solution sizing summary, send a copy, or make a copy?15. Is the customer information I enter into the Unified Communications ST secure?16. In what languages is the Unified Communications ST available?

17. I found more than one DSP calculator on www.cisco.com. Which one should I use?

About Sizing

1. What is an Erlang?2. What is BHCA?3. How many simultaneous calls can a server support?

4. What is the BHCA per server or cluster?5. How do I determine the number of CTI connections?6. Why is my CPU utilization low or memory utilization low, but the tool is specifying multiple

servers.

7. For Unified CCE (IPCC), why does the tool have an input for incoming calls rather than number of agents ?

8. What is the difference in call processing cost for gatekeeper-controlled versus non-gatekeeper controlled?

9. Why is it necessary to distinguish between KPML dialing and en bloc dialing on the phones?10. I am sizing a system that has two distinct sets of users, which each have different core office hours.

How do I come up with a BHCA for this environment?11. Why does the Unified Communications ST ask for the input BHCA excluded conferencing?12. How many voice messaging ports do I need?13. If the Unified Communications ST tells me I cannot scale any more due to memory constraints, can

I fix this by adding more memory to the server?14. Does the Unified Communications ST guide me in how much network bandwidth I will need?15. Can the Unified Communications ST help me size my system if all I know is the number of IP

phones?

16. Is there a difference in the effect of devices using different protocols, such as SIP, SCCP, MGCP, or H.323, and does the Unified Communications ST account for this?

17. What information do I need to obtain before running the Unified Communications ST?18. How do I know the results of a sizing exercise are accurate?19. How does the number of Unified Contact Center agents affect the Unified CM component?20. How many gateway ports or PSTN trunks do I need?21. When should I choose the Complex option for the Database Complexity field in the Unified CM

Deployment page?22. What is ECC?23. What is a PG?24. What is a Progger?25. What is IPCC?26. I am trying to perform calculations for an agent-less campaign, but the toolshows me that I still need

agents. What do I do?2Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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About the Unified Communications ST

Q. Who can access the Unified Communications Sizing Tool?A. Any Cisco employee with a Cisco.com account. The Cisco.com account can also be provided to

partners who are either members of the Cisco Technology Developer Program (CTDP) or hold one of the following specializations: Advanced Unified Communications Specialization Master Unified Communications Specialization Multinational Master Unified Communications Satellite Specialization ATP-Customer Voice Portal Authorized Unified MeetingPlace (ATP-Rich Media Communications) ATP-Unified Contact Center Enterprise

Q. What products and versions does the Unified Communications ST support?A. A complete list of supported products can be found in the Release Notes for Cisco Unified

Communications Sizing Tool.

Q. How do I learn how to use the Unified Communications ST?A. All links to documents and training or demonstration VODs are available under the Documentation

& Training tab in the Unified Communications Sizing Tool.

Q. How is Unified Communications ST better than Cisco Unified Communications Manager Capacity Tool?

A. Unified Communications ST provides sizing guidance for Unified Communications systems, not just Communications Manager clusters. Unified Communications ST helps to size other components of the Unified Communications system, including Unified Contact Center, Cisco Unity, and Cisco MeetingPlace. It also automatically calculates and predicts the effects of supported components on the performance and sizing of the Unified Communications Manager clusters.

Q. Can I use the output of Unified Communications ST to enter information into the Unified CMCT?A. The Unified Communications ST renders the Unified CMCT obsolete. It provides more

comprehensive design guidance than the Unified CMCT, so there is no need to use Unified CMCT when you have Unified Communications ST.

Q. Can I use the output of Unified Communications ST to enter information into the Unified CCE Sizing Tool?

A. The Unified Communications ST provides more comprehensive design guidance than the Unified CCE Sizing Tool, so there is no need to use the Unified CCE Sizing Tool.

Q. Why cant Unified CM be sized as an individual component?A. Unified CM requires Gateways as part of the sizing therefore it cannot be sized as a separate

component. Please use the System Release or Compatible Components Sizing scenario as possible scenarios to size Unified CM.

Q. How can I size a system based on Unified CM 4.x? A. Use the Unified Communications Manager Capacity Sizing Tool (Unified CMCT)3Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Q. Can anyone use Unified Communications ST?A. No, only Cisco employees, authorized resellers and channel partners can access the Unified

Communications ST.

Q. How do I install the Unified Communications ST?A. You dont need to install it. The Unified Communications ST runs as a server-based application that

you connect to with a web browser.

Q. What browser can I use to access the Unified Communications ST?A. The Unified Communications ST officially supports the following browsers: Microsoft Internet Explorer 6.0, 7.0, 8.0 Apple Safari 3.x, 4.x Mozilla Firefox 2.x, 3.x Google Chrome

Q. How do I save my sizing solution for later reference?A. The My Solutions tab on the Unified Communications ST lets you save, copy, and send solutions to

another cisco.com user.

Q. How do I download a solution sizing summary report?

Q. Click the Export button on the Solution Sizing Summary page. On the download dialog box that appears, browse the location to download the report and click Save. The solution sizing summary report will be saved in PDF format.

Q. What are the Internet Explorer browser settings required to revalidate old solutions for new Unified Communications ST releases, download a solution sizing summary, send a copy, or make a copy?

A. Perform these steps to modify the Internet Explorer security settings for downloading the solution sizing summary report:

1. On your system task bar, go to Start-> Control Panel->Internet Options. 2. On the Internet Options panel, click Security tab. Click Trusted Sites icon. Click Sites button. 3. On the Trusted Sites dialog box, ensure that the checkbox Require server verification (https:)

for all sites in this zone is not selected. Enter the URL http://tools.cisco.com into the input field Enter this Web site to the zone. Click Add. Click OK to close the Trusted Sites dialog box.

4. Click Custom Level button on Security tab. Scroll down on the Security Settings panel to the Downloads section. Select Enable for Automatic prompting for the file downloads and File Download options. Scroll further down to Miscellaneous section and select Disable for Use pop up blocker option. Click OK on Security Settings panel.

5. Click OK to close the Internet Options panel.

Q. Is the customer information I enter into the Unified Communications ST secure?A. A standard cisco.com account is used for authentication to prevent unauthorized access. The Java

executable for the Unified Communications ST is only available for running on-line, to help prevent reverse engineering. The Unified Communications ST protects information from viewing by anyone except the owner, unless the owner chooses to send a copy of a specific solution.4Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Q. In what languages is the Unified Communications ST available?A. The Unified Communications ST is available only in English.

Q. I found more than one DSP calculator on www.cisco.com. Which one should I use?A. The Cisco Unified Communications Sizing Tool can be used to size Cisco ISR gateways and DSPs

either as a standalone request or as part of sizing the larger Cisco UC solution. The access to this tool is restricted to Cisco Field and Unified Communications certified Cisco Partners.If you are not a Cisco Partner and want to determine what DSPs to order on your ISRs, you can use the DSP Calculator tool at www.cisco.com/go/dspcalculator.If you want to determine DSP capability on older Cisco non-ISR gateway platforms, you can access the legacy calculator at http://www.cisco.com/cgi-bin/Support/DSP/cisco_dsp_calc.pl, which covers platforms and software releases not supported in the ISR G2 DSP Calculator tool nor in the Unified Communications Sizing Tool such as the 1700, 2600, 3700 and AS5000 platforms and/or IOS releases preceding, and up to, 12.4 mainline. This calculator will not be updated for new releases or platforms but will continue to cover the legacy platforms not included in the other tools.

About Sizing

Q. What is an Erlang?A. An Erlang is a unit of measure for communications traffic. It is used to represent the utilization of

a resource over a one-hour period. One Erlang means that one resource was used 100% of the hour. This could have been due to a single call of one-hour duration, or multiple sequential calls whose durations add to one hour. Therefore, if 10 Erlangs are required, it is necessary to have 10 resources to ensure that all traffic is serviced.

Q. What is BHCA? A. Busy Hour Call Attempts is a measure of call volume indicating the number of call attempts that are

presented to a system during the busiest one-hour period. The concept allows a more accurate prediction of system capacity because it represents a peak load over a relatively short period. BHCA can be measured over any time period, but typically a day is used. In some environments, there may be a particular hour in a week, or in a year where traffic volume is much greater. For example in the PSTN, the busiest day for calls is Mothers Day. It is recommended that you determine and use the highest call rate during the longest time period that you can measure.

Q. How many simultaneous calls can a server support?A. There is no absolute number of simultaneous calls that can occur on a server. It depends on the

amount of memory that is available and is calculated by the Unified Communications ST based on multiple inputs.

Q. What is the BHCA per server or cluster?A. An absolute BHCA is not specified. Rather the tool takes into account different costs of different

types of call flows. The tool accounts for differences in cost, such as calls using different protocols (SIP or SCCP), shared lines, the type of endpoints involved, and other factors. Therefore there is no flat BHCA budget per server. The BHCA for a cluster depends on the number of subscribers because each subscriber adds additional BHCA capacity to the cluster.5Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Q. How do I determine the number of CTI connections?A. The number of CTI connections that the system needs to manage are determined by the inputs made

in the Unified Communications Manager > Applications tab of the Unified Communications ST. The system tracks the number of CTI controlled devices, CTI controlled lines or directory numbers (DNs), and the average number of CTI applications that control each of these devices. The system is sized based on all of these values. Note that lines and DNs that are shared among multiple devices may also have a CTI cost.

Q. Why is my CPU utilization low or memory utilization low, but the tool is specifying multiple servers.

A. In addition to memory and CPU utilization, the Unified Communications ST also tracks specific hard limits in the system. The number of servers may be larger due to specific limits of the number of phones, the number of CTI-controlled devices, the number of agents, or other factors.

Q. For Unified CCE (IPCC), why does the tool have an input for incoming calls rather than number of agents ?

A. The tool calculates the number of agents based on incoming calls and taking into account service level agreements (SLA) and supervising agents. The tool suggests the number of agents required as an output.

Q. What is the difference in call processing cost for gatekeeper-controlled versus non-gatekeeper controlled?

A. There is no difference in the actual cost, but the tool input is structured to reflect the configuration of the Unified CM. The Unified CM is configured with gatekeeper-controlled gateways as a separate item.

Q. Why is it necessary to distinguish between KPML dialing and en bloc dialing on the phones?A. The cost to the system for each type of dialing is different and is included to ensure a high level of

precision in the calculations. KPML is more expensive, but is the default for SIP phones that support it.

Q. I am sizing a system that has two distinct sets of users, which each have different core office hours. How do I come up with a BHCA for this environment?

A. BHCA is meant to reflect the number of calls attempted at the busiest hour of the day. So it is not significant that there are two distinct sets of users. The information required to calculate BHCA is the total highest load on the system in a one-hour interval.

Q. Why does the Unified Communications ST ask for the input BHCA excluded conferencing?A. Conferencing is bursty traffic that occurs at the top of the hour because most conferences start on an

hour or half-hour boundary. The Unified Communications ST accounts for this traffic differently because it is highly concentrated. It determines the BHCA due to conferencing based on the number of conferences initiated and a specified period when those conferences are initiated. This results in a more precise calculation for the bursty conferencing traffic.

Q. How many voice messaging ports do I need?A. The Unified Communications ST calculates the number of voice messaging ports based on the

number of messages sent during the busy hour and whether IMAP or CPCA is used for retrieving messages.6Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Q. If the Unified Communications ST tells me I cannot scale any more due to memory constraints, can I fix this by adding more memory to the server?

A. Overall extra memory does improve the performance of an operating system for running multiple processes. However, the amount of Virtual Memory space is the important factor and the Unified Communications ST does sizing based on the maximum VM available for a specific Unified CM version. Additional memory would not increase that VM space and does not provide extra capacity.

Q. Does the Unified Communications ST guide me in how much network bandwidth I will need?A. No, not at this time.

Q. Can the Unified Communications ST help me size my system if all I know is the number of IP phones?

A. Default values are provided for many inputs and can be used to provide useful output. If you accept the defaults, then the system you implement should be monitored to verify that the defaults are not being exceeded. If the default values for system activity are exceeded, rerun the tool with the actual data to verify that your solution has sufficient capacity.

Q. Is there a difference in the effect of devices using different protocols, such as SIP, SCCP, MGCP, or H.323, and does the Unified Communications ST account for this?

A. Yes the tool accounts for differences in protocols used by devices and different call flow patterns of those devices.

Q. What information do I need to obtain before running the Unified Communications ST?A. You can view the input fields in the Unified Communications ST interface to determine the

information required.

Q. How do I know the results of a sizing exercise are accurate?A. The calculations are based on performance testing of the system. The accuracy of the result you get

depends on the accuracy of your inputs. The output of the tool may differ from your observations. For instance, the tool provides a percentage of a CPU budget rather than the total CPU usage. Additionally, the CPU utilization shown by the tool refers to the CPU utilized by the Unified CM process rather than overall CPU utilization of a specific server.

Q. How does the number of Unified Contact Center agents affect the Unified CM component?A. The number agents is used to calculate the expected BHCA load on the Unified CM.

Q. How many gateway ports or PSTN trunks do I need?A. The tool derives a number of ports from your input on the percentage of the BHCA load that will

involve gateways and also the required service level specified by the blocking probability.

Q. When should I choose the Complex option for the Database Complexity field in the Unified CM Deployment page?

A. The tool allows selection of two levels of dial plan complexity: Simple and Complex. The Database Complexity option uses a fixed multiplier for all the dial plan-related performance data. Select the Complex choice when a dial plan includes non-trivial call flows. For example, hunt lists generate multiple calls for each incoming call to the hunt list. This would not be reflected in the BHCA for the overall system, and you should choose the Complex Database option. In general, you should also choose the Complex Database option for deployments over 10,000 phones because these deployments typically use advanced dial plan constructs.7Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Q. What is ECC?A. Expanded Call Context are variables that are defined and enabled in the Configuration Manager to

store values associated with the calls and pass the associated data between different ICM/IPCC components. ECC variables can be defined up to 2Kbyte size.

Q. What is a PG?A. Peripheral Gateway: The computer and process within the ICM system that communicates directly

with the CM, ACD, PBX, or ICM at a contact center. The Peripheral Gateway reads status data from the peripheral and sends it to the Central Controller. In a private network configuration, the Peripheral Gateway sends routing requests to the Central Controller and receives routing information in return.

Q. What is a Progger?A. This is an ICM deployment model when ICM - Router, ICM - Logger and ICM - PG are based on

one platform.

Q. What is IPCC?A. IP Contact Center is the previous name for Cisco Unified Contact Center.

Q. I am trying to perform calculations for an agent-less campaign, but the toolshows me that I still need agents. What do I do?

A. Access the Unified Contact Center Enterprise > Outbound tab of the Unified Communications ST. In the Input area, select Ports and enter the number of ports in the Ports or Agents field. In the Answered Calls Summary area, enter 100 in the Event(%) field for the Transferred to IVR settings, and enter 0 in the Event(%) field for the Transferred and Answered by Agent settings.8Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)

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Unified Communications Sizing Tool Release 8.6(2): Frequently Asked Questions (FAQ)About the Unified Communications STAbout SizingAbout the Unified Communications STAbout Sizing