Design Guide for Cisco Unity Connection Release 8.x
Sizing and Scaling Cisco Unity Connection 8.x Servers
Downloads: This chapterpdf (PDF - 169.0KB) The complete bookPDF (PDF - 2.35MB) | Feedback

Sizing and Scaling Cisco Unity Connection 8.x Servers

Table Of Contents

Sizing and Scaling Cisco Unity Connection 8.x Servers

Audio Codecs

Audio Codec Usage for Call Connections and for Recording

Audio Codec Considerations for VPIM Networking

Voice Messaging Ports

Storage Capacity for Voice Messages

Users

Simultaneous TUI/VUI Sessions

IMAP Clients Used to Access Connection Voice Messages

Visual Voicemail Clients and Sessions

Simultaneous Mobile Clients

Messaging Assistant Clients

Web Inbox Clients (Cisco Unity Connection 8.5 and Later Only)

Messaging Inbox Clients (Cisco Unity Connection 8.0 Only)

Cisco Unified Personal Communicator Clients

IBM Lotus Sametime Clients

RSS Reader Clients


Sizing and Scaling Cisco Unity Connection 8.x Servers


When sizing a Cisco Unity Connection server, follow the guidelines in the following sections:

Audio Codecs

Voice Messaging Ports

Storage Capacity for Voice Messages

Users

Simultaneous TUI/VUI Sessions

IMAP Clients Used to Access Connection Voice Messages

Visual Voicemail Clients and Sessions

Simultaneous Mobile Clients

Messaging Assistant Clients

Web Inbox Clients (Cisco Unity Connection 8.5 and Later Only)

Messaging Inbox Clients (Cisco Unity Connection 8.0 Only)

Cisco Unified Personal Communicator Clients

IBM Lotus Sametime Clients

RSS Reader Clients

For a list of servers that meet Connection specifications, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

Audio Codecs

See the following sections:

Audio Codec Usage for Call Connections and for Recording

Audio Codec Considerations for VPIM Networking

Audio Codec Usage for Call Connections and for Recording

In Cisco Unity Connection, a call in any audio codec format that is supported by Connection SCCP or SIP signaling—G.711 mu-law, G.711 a-law, G.722, G.729, and iLBC—will always be transcoded to PCM linear. From PCM linear, the recording is encoded in the system-level recording audio codec—PCM linear, G.711 mu-law, G.711 a-law, G.729a, or G.726—a systemwide setting in Cisco Unity Connection Administration. G.711 mu-law is the default.

In this section, we refer to the audio codec that is negotiated between the calling device and Connection as the "line codec," and the audio codec that is set as the system-level recording audio codec as the "recording codec."

Supported Line Codecs (Advertised Codecs)

G.711 mu-law

G.711 a-law

G.722

G.729

iLBC

Supported Recording Codecs (System-Level Recording Audio Codecs)

PCM linear

G.711 mu-law (default)

G.711 a-law

G.729a

G.726

GSM 6.10

Because transcoding occurs in every connection, there is little difference in system impact when the line codec differs from the recording codec. For example, using G.729a as the line codec and G.711 mu-law as the recording codec does not place a significant additional load on the Connection server for transcoding. However, the iLBC or G.722 codecs require more computation to transcode, and therefore places a significant additional load on the Connection server. Consequently, a Connection server can support only half as many G.722 or iLBC connections as it can G.711 mu-law connections.


Note Use of the G.722 or iLBC codec as line codecs or advertised codecs reduces the number of voice ports that can be provisioned on the Cisco Unity Connection server. For more information on the number of voice ports supported for each platform overlay when using G.722 or iLBC codecs, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.


Generally, we recommend that you do not change the system recording format from the default setting except in the following situations:

To address disk space considerations, consider using a low bit-rate codec such as G.729a or G.726. Note that a low bit-rate codec produces lower quality audio than a high bit-rate codec such as G.711 mu-law.

To improve the audio quality of recordings for endpoints that use G.722 as the line codec, consider using PCM linear. Note that PCM linear increases the disk space that is used.

There are additional possible reasons to change the recording codec or to choose only to advertise specific line codecs. Review the following information when making decisions on the system-level recording audio codec and the advertised codecs on the SCCP or SIP integration:

The audio codecs that will be negotiated between the majority of the endpoints and Connection. This information will help you decide the audio codecs that Connection should advertise and the audio codecs that Connection should not advertise. You can then decide when you need Cisco Unified Communications Manager to provide hardware transcoding resources rather than using Connection to provide computationally significant native transcoding, such as when the configuration requires a number of clients to connect to Connection by using G.722 or iLBC.

The types of graphical user interface (GUI) clients that will play the recordings (for example, web browsers, email clients, or media players) and the audio codecs that these GUI clients support.

The quality of the sound produced by the selected audio codec. Some audio codecs produce higher audio quality than other audio codecs. For example, G.711 produces a higher audio quality than G.729a and is a better choice when higher audio quality is necessary.

The amount of disk space that the audio codec takes up per second of recording time.

PCM linear produces the highest audio quality and is the most widely supported by media players, yet it uses the most disk space and bandwidth (16 KB/sec). G.711 (both a-law and mu-law) produces moderate audio quality compared to PCM linear and is also widely supported by media players, though it uses half as much disk space and bandwidth (8 KB/sec). G.729a produces the lowest audio quality of the four supported audio codecs and is poorly supported by media players because it requires a license for use. Yet this audio codec uses the least amount of disk space (1 KB/sec). G.726 produces moderate audio quality, is moderately supported by media players, and uses less disk space than most of the other codecs (3 KB/sec). This information is summarized in Table 3-1.

Table 3-1 Comparison of Audio Codecs Used for Recording 

Recording Audio Codec
Audio Quality
Supportability
Disk Space Used
Sampling Rate
Channels
Sample Size

PCM linear

Highest

Widely supported

16 KB/sec

8 kHz/sec

1

16 bits

G.711 mu-law/a-law

Moderate

Widely supported

8 KB/sec

8 kHz/sec

1

8 bits

G726

Moderate

Moderately supported

4 KB/sec

8 kHz/sec

1

4 bits

GSM 6.10

Moderate

Poorly supported

1.63 KB/sec

8 kHz/sec

1

N/A

G.729a

Lowest

Poorly supported

1 KB/sec

8 kHz/sec

1

N/A


For details on changing the audio codec that is advertised by Connection, or the system-level recording audio codec, see the "Changing the Audio Format of Recordings and Media Streams in Cisco Unity Connection 8.x" chapter of the System Administration Guide for Cisco Unity Connection Release 8.x, at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/administration/guide/8xcucsagx.html.

When modifying the advertised audio codecs, the choices are G.711 mu-law, G.711 a-law, G.722, G.729, and iLBC. In addition, you also indicate an order of preference for the chosen codecs.

For SCCP integrations, the order of the audio codecs is not important because Cisco Unified CM negotiates the audio codec based on the location of the port and the device in the negotiated call. However, for SIP integrations the order of the audio codecs is important. If one audio codec is preferred over another audio codec, Connection will advertise that it supports both audio codecs but will prefer to use the one specified over the other.

Audio Codec Considerations for VPIM Networking

If VPIM networking connects Cisco Unity Connection to another Connection server, to a Cisco Unity server, or to a third-party voice-messaging system, you must choose a compatible audio codec.

Note the following audio codec considerations for Connection VPIM networking:

For inbound messages, Connection can do one of the following:

Convert voice messages to any audio format that Connection supports.

Not convert the audio format of the voice message, keeping the voice message in its original audio format.

For outbound voice messages, Connection can do one of the following:

Convert voice messages to the G.726 audio format.

Not convert the audio format of the voice message, keeping the voice message in its original audio format. Not converting is useful when you use VPIM networking to send voice messages between Connection servers, or between Connection and Cisco Unity servers.

For more information on VPIM Networking, see the "VPIM Networking" section.

Voice Messaging Ports

Revised November 16, 2010

To determine the number and configuration of voice messaging ports required, consider the following:

The existing voice messaging system—Evaluate how well the existing voice messaging system functions, if applicable. This evaluation may give you some idea how many ports are needed for taking voice messages, for turning message waiting indicators (MWIs) on and off, and for message notification.

Use of the Web Inbox web client (Connection 8.5 and later), Messaging Inbox web client (Connection 8.0) or the Cisco Unity Connection ViewMail for Microsoft Outlook client—When users use the Web Inbox web client, the Messaging Inbox web client, or the Cisco Unity Connection ViewMail for Microsoft Outlook client, Cisco Unity Connection uses telephone record and playback (TRAP) to allow users to play and record voice messages by phone rather than by using speakers and a microphone. This feature is especially useful when users work in cubicles, where there is a lack of privacy. However, when a user plays or records a message by using TRAP, a port on the Connection server is used. (No port is used when a user uses speakers and a microphone to play and record messages.) If the customer wants users to use TRAP, calculations for the total number of voice ports required will need to take this into account.

Cisco Unity Connection cluster—In some cases, an existing voice messaging system has more voice messaging ports than Connection supports. When configured as a Connection cluster (an active/active high availability Connection server pair), the Connection system can support double the number of voice messaging ports compared to a single-server deployment. For more information, see the "Cisco Unity Connection 8.x Clusters (Active/Active High Availability)" chapter.

Networking—The customer can purchase additional Connection servers or Connection cluster pairs and connect them by using intrasite and/or intersite networking to increase the number of voice ports supported. For more information, see the "Networking in Cisco Unity Connection 8.x" chapter.

For additional information on the number of voice messaging ports, see the "Planning How the Voice Messaging Ports Will Be Used by Cisco Unity Connection" section in the applicable Cisco Unity Connection integration guide at http://www.cisco.com/en/US/products/ps6509/products_installation_and_configuration_guides_list.html.

Storage Capacity for Voice Messages

For Cisco Unity Connection systems that are configured to store voicemails only (no emails or faxes will be stored on the server), base the server requirements on the total number of voice storage minutes required for each user. A supported Connection server generally provides storage for at least 20 to 30 minutes of voice messages per user for the maximum number of users supported on that server. See the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html for the exact amount of voice-message storage supported for each server.

For Connection systems that are configured to store faxes and email replies to voice messages in addition to voice messages, you cannot base server requirements on the total number of voice-storage minutes required for each user because the message store on the Connection server will also include faxes and possibly email. However, you can calculate the storage requirement for the desired number of voice-storage minutes and add that to the current mailbox limits.

For Connection systems that are configured to store faxes and email replies to voice messages in addition to voice messages, start with the total number of voice-storage minutes required for each user, and add the amount of storage space that you want users to have for faxes. In general, the email stored in Connection should not significantly affect storage capacity.


Note The email stored in Connection is only replies to or forwards of Connection voice messages, with or without the original voice message. This email is not related to email in the email inbox of the user.


If the customer is replacing an existing voice-messaging system with Connection, it may be possible to obtain information from the existing system on the average number of minutes of voice messages that users currently have. You can then multiply the average number of minutes by the recording size per minute—according to the codec that Connection will use to record messages—to arrive at the average amount of disk space required for voice messages per user.

Start with a one-to-one correlation between the legacy voice-messaging system and Connection. If the legacy system handles a larger capacity than the largest Connection server, consider splitting the legacy user population onto more than one Connection server.

Users

Revised November 16, 2010

See the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html for the maximum number of users supported for each supported server. Planning and selection of servers should take into account the possibility of adding users in the future.

For information on moving users from one Cisco Unity Connection server to another, see the "Moving Users Between Locations in Cisco Unity Connection 8.x" chapter of the User Moves, Adds, and Changes Guide for Cisco Unity Connection Release 8.x, at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/user_mac/guide/8xcucmacx.html.

Simultaneous TUI/VUI Sessions

Revised November 16, 2010

To determine the maximum number of simultaneous TUI (touchtone conversation) and/or VUI (voice-recognition) sessions that Cisco Unity Connection can support, consider the following:

Connection cluster—If a Connection cluster server pair is configured (active/active high availability) instead of a standalone Connection server, the maximum number of TUI and/or VUI sessions supported is doubled for each platform overlay. For the maximum number of sessions that Connection can support for each platform overlay when a Connection cluster is configured, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

Desktop Clients—When desktop clients (for example, the Web Inbox (Connection 8.5 and later), the Messaging Inbox (Connection 8.0), and IMAP) are deployed, the maximum number of TUI and/or VUI sessions that Connection supports is reduced for Platform Overlay 1 servers. For more information, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

Note that some IMAP clients (for example, Cisco Unified Personal Communicator 7.0 and earlier) do not support the IMAP IDLE command. IMAP clients that do not support IMAP IDLE consume more system resources on a Connection server. As a result, each active instance of each client that does not support IMAP Idle and is accessing Connection voice messages counts as four active clients. See the "IMAP Clients Used to Access Connection Voice Messages" section for additional details.

G.722 and iLBC Audio Codecs—Using G.722 or iLBC audio codecs "on the line" or as advertised codecs reduces the maximum number of TUI and/or VUI sessions that Connection supports for each platform overlay by 50 percent as compared to using the G.711 audio codec. For the maximum number of sessions that Connection supports for each platform overlay when using the G.722 or iLBC audio codec, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html. For a discussion of supported system recording and advertised or "on the line" audio codecs with Connection, see the "Audio Codecs" section.

IMAP Clients Used to Access Connection Voice Messages

Third-party IMAP clients such as email clients are supported for accessing voice messages from Cisco Unity Connection. Scalability of IMAP clients depends on whether they support IMAP Idle. Using clients that support IMAP Idle reduces the load on the Connection server; a Connection server can support four times as many IMAP Idle clients as it can non-IMAP Idle clients. (IMAP Idle, described in RFC 2177, allows a client to indicate to the server that it is ready to accept real-time notifications.)

Most third-party IMAP email clients, such as Microsoft Outlook and Lotus Notes, support IMAP Idle. Cisco Unified Personal Communicator (CUPC) version 8.0 and later supports IMAP idle. The Cisco Unity Connection Plug-in for IBM Lotus Sametime version 7.11 and later supports IMAP idle. Among the clients that do not support IMAP Idle are Cisco Unified Mobility Advantage and Cisco Unified Mobile Communicator. For information on whether a client supports IMAP Idle, see the documentation for the client. For information on the number of IMAP clients supported for each platform overlay (each grouping of comparable supported Connection servers), see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

You can mix IMAP Idle and non-IMAP Idle clients if necessary. However, to simplify sizing calculations, we recommend that you isolate IMAP Idle and non-IMAP Idle clients on separate Cisco Unity Connection servers or cluster server pairs (active/active high availability). If you must mix IMAP Idle and non-IMAP Idle clients on the same server or cluster server pair, count each non-IMAP Idle client as four IMAP Idle clients for sizing calculations. In addition, you may want to put users who use IMAP Idle clients and users who use non-IMAP Idle clients into separate classes of service so that you can run a report that tells you how many of each you have accessing voice messages on a given Connection server.

Note that when you isolate IMAP Idle and non-IMAP Idle clients on separate servers or cluster server pairs, you should set up networking between the servers if they are not already networked. For more information on Connection networking, see the "Networking in Cisco Unity Connection 8.x" chapter.

Visual Voicemail Clients and Sessions

Revised November 16, 2010

The maximum number of Visual Voicemail clients is equivalent to the maximum number of users supported by a Cisco Unity Connection server or by a Cisco Unity Connection cluster (active/active high availability) server pair. For the maximum number of Visual Voicemail clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

The maximum number of Visual Voicemail sessions is equivalent to the maximum number of ports available on a Connection server or Connection cluster (active/active high availability) server pair. For the maximum number of Visual Voicemail sessions or ports supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For supported versions of Cisco Unified Communications Manager and Cisco IP Phones with the Visual Voicemail feature, see System Requirements for Cisco Unity Connection Release 8.x at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/requirements/8xcucsysreqs.html.

For system requirements, see the Release Notes for Visual Voicemail Release 8.5 at http://www.cisco.com/en/US/docs/voice_ip_comm/cupa/visual_voicemail/8.5/release/notes/vivoReleaseNote85.html.

For installation and configuration information, see the Installation and Configuration Guide for Visual Voicemail Release 8.5 at http://www.cisco.com/en/US/docs/voice_ip_comm/cupa/visual_voicemail/8.5/install/guide/vv_install.html.

For end-user information, see the Quick Start Guide: Visual Voicemail Release 8.5 at http://www.cisco.com/en/US/docs/voice_ip_comm/cupa/visual_voicemail/8.5/quick_start/guide/b_Quick_Start_Guide_for_Visual_Voicemail_Release_8.5.html.

(For information on using Phone View, an older application that provides limited access to messages from the phone display, see the "Phone View Clients and Sessions" section in the "Sizing and Scaling Cisco Unity Connection Servers" chapter of the Design Guide for Cisco Unity Connection Release 7.x, at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/7x/design/guide/7xcucdg.html.)

Simultaneous Mobile Clients

Cisco Unified Mobility Advantage (CUMA) Release 7.0 connects to the Cisco Unity Connection server by using IMAP, so it is considered an IMAP client. Because the Cisco Unified Mobility Advantage IMAP connection is not an IMAP Idle connection, the maximum number of simultaneous mobile clients supported by Cisco Unified Mobility Advantage, Cisco Unified Mobile Communicator, and Connection is reduced by approximately 70 percent. For the maximum number of Cisco Unified Mobility Advantage clients and Cisco Unified Mobile Communicator clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on integrating Connection with Cisco Unified Mobility Advantage, see the "Creating a Cisco Unified Mobility Advantage Integration in Cisco Unity Connection 8.x" chapter of the System Administration Guide for Cisco Unity Connection Release 8.x, at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/administration/guide/8xcucsagx.html.

Messaging Assistant Clients

The maximum number of Messaging Assistant clients is equivalent to the maximum number of users supported by a Cisco Unity Connection server or by a Connection cluster (active/active high availability) server pair. For the maximum number of Messaging Assistant clients or users supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on using the Messaging Assistant, see the User Guide for the Cisco Unity Connection Personal Call Transfer Rules Web Tool (Release 8.x) at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/user/guide/pctr/b_8xcucugpctr.html.

Web Inbox Clients (Cisco Unity Connection 8.5 and Later Only)

Added November 16, 2010

For the maximum number of Web Inbox clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on using the Web Inbox, see the Quick Start Guide for the Cisco Unity Connection Web Inbox (Release 8.5 and Later) at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/quick_start/guide/85xcucqsginbox.html.

Messaging Inbox Clients (Cisco Unity Connection 8.0 Only)

For the maximum number of Messaging Inbox clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on using the Messaging Inbox, see the User Guide for the Cisco Unity Connection Messaging Inbox Web Tool (Release 8.x) at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/user/guide/inbox/b_8xcucuginbox.html.

Cisco Unified Personal Communicator Clients

The Cisco Unified Personal Communicator (CUPC) client does not support IMAP Idle, so the number of CUPC clients supported by a Cisco Unity Connection server or by a Connection cluster (active/active high availability) server pair is lower than the maximum number of users. For the maximum number of CUPC clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on using CUPC, see the applicable Cisco Unified Personal Communicator user guide at http://www.cisco.com/en/US/products/ps6844/products_user_guide_list.html.

IBM Lotus Sametime Clients

The voice messaging plug-in for the IBM Lotus Sametime client does not support IMAP Idle, so the number of IBM Lotus Sametime clients supported by a Cisco Unity Connection server or by a Connection cluster (active/active high availability) server pair is lower than the maximum number of users. For the maximum number of IBM Lotus Sametime clients supported for each platform overlay, see the Cisco Unity Connection 8.x Supported Platforms List at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/supported_platforms/8xcucspl.html.

For information on the IBM Lotus Sametime client, see the applicable version of Release Notes for Cisco Unified Messaging with IBM Lotus Sametime at http://www.cisco.com/en/US/products/ps6509/prod_release_notes_list.html.

RSS Reader Clients

The maximum number of RSS reader clients is equivalent to the maximum number of users supported by a Cisco Unity Connection server or by a Connection cluster (active/active high availability) server pair.

For more information on the RSS Feed feature and RSS reader clients, see the "Configuring Access to RSS Feeds of Voice Messages in Cisco Unity Connection 8.x" section in the "Messaging in Cisco Unity Connection 8.x" chapter of the System Administration Guide for Cisco Unity Connection Release 8.x, at http://www.cisco.com/en/US/docs/voice_ip_comm/connection/8x/administration/guide/8xcucsagx.html.