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Cisco IP Telephony Solution Reference
Network Design Guide
Cisco CallManager Release 3.1 and 3.2
July 2003
Customer Order Number: 956378
Text Part Number: EDCS-197018

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World Wide Web
xv
Documentation CD-ROM
xv
Ordering Documentation
xv
Documentation Feedback
xv
Obtaining Technical Assistance
xvi
Cisco.com
xvi
Technical Assistance Center
xvi
Cisco TAC Web Site
xvii
Cisco TAC Escalation Center
xvii
CHAPTER

1
Overview of Cisco AVVID IP Telephony Solutions
1-1
Why IP Telephony?
1-1
Architecture Overview
1-3
Security
1-4
Quality of Service

Cisco IP Telephony Solution Reference Network Design Guide
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Cisco Customer Response Solutions Platform
1-10
Cisco IP Integrated Contact Distribution (IP ICD)
1-10
Cisco IP Interactive Voice Response (IP IVR)
1-11
Components That Apply to All Deployment Models
1-11
Voice, Fax, and Modem Gateways
1-11
Station Devices
1-12
Emergency Services (911 and E911)
1-12
CHAPTER

2
IP Telephony Deployment Models
2-1
Single Site
2-2
Solution Benefits
2-3
Best Practices
2-4
Dial Plan
2-4
Multi-Site WAN with Centralized Call Processing

2-20
Hybrid Dial Plan
2-20
Clustering Over the IP WAN
2-21
Local Failover Deployment Model
2-22
Cisco CallManager Provisioning
2-23
Gateways
2-24
Voice Mail
2-24
Music on Hold
2-24
Remote Failover Deployment Model
2-25
Cisco CallManager Provisioning
2-26
Gateways
2-26

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Voice Mail
2-27
Music on Hold
2-27


4
Choosing a Cisco IP Telephony Gateway
4-1
Understanding Cisco Gateways
4-1
Cisco Access Analog Gateways
4-1
Cisco Access Digital Trunk Gateways
4-2
Gateway Requirements
4-2
Gateway Protocols
4-2
Selecting the Gateway Protocol
4-3
Gateway Protocol and Core Feature Requirements
4-4
DTMF Relay
4-5
SCCP Gateways
4-5
H.323 Gateways
4-5
MGCP Gateway
4-5
Supplementary Services
4-5
SCCP Gateways
4-6


5
Transcoding, Conferencing, and MTP Resources
5-1
Media Resource Types
5-1
Media Termination Point (MTP)
5-1
Transcoder
5-2
Unicast Conference Bridge
5-2
MTP and Transcoding Resources
5-3
Software MTP Resources
5-4
Hardware MTP and Transcoding Resources
5-4
Catalyst 4000 MTP and Transcoding Services
5-5
Catalyst 6000 MTP and Transcoding Services
5-5
Cisco Catalyst MTP Constraints
5-6
Cisco VG200 MTP and Transcoding Services
5-7
Cisco ICS 7750 MTP and Transcoding Services
5-7
Provisioning MTP and Transcoding Resources
5-8

Multi-Site WAN Deployments with Distributed Call Processing
5-22
CHAPTER

6
Call Processing with Cisco CallManager
6-1
Cluster Operation and Scalability Guidelines
6-1
Device Weights
6-3

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Server Memory Requirements
6-7
Intracluster Communication
6-7
Cisco CallManager Redundancy
6-8
Redundancy Group Configuration
6-9
Device Pool Configuration
6-10
Clustering Guidelines
6-12
Intercluster Communication
6-13

CHAPTER

7
Call Admission Control
7-1
Bandwidth Calculations
7-2
Call Admission Control with Cisco CallManager Locations
7-2
Call Admission Control with a Gatekeeper
7-4
Gatekeeper Operations
7-5
Gatekeeper Discovery
7-5
Registration Process
7-6
Admission Requests
7-7
Disengage Request
7-8
Bandwidth Requests
7-8
Technology Prefix
7-9
E.164 Address Resolution
7-9
ARQ Parsing Order
7-10
Cisco IOS Gatekeeper Commands

8-7
Route Lists
8-11
Route Groups
8-14
Devices
8-15
Calling Restrictions
8-16
Partitions
8-16
Calling Search Spaces
8-16
Translation Patterns
8-19
Voice Mail Integration and Cisco CallManager Dial Plans
8-21
Voice Mail Integration via SCCP
8-23
Voice Mail Integration via SMDI
8-23
Dial Plan Guidelines for IP Telephony Deployment Models
8-25
Single-Site Deployment
8-26
Multi-Site IP WAN with Distributed Call Processing
8-28
Route Pattern Structure
8-29
Partitions and Calling Search Spaces


Contents
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Cisco Unity
9-7
Cisco Digital PBX Adapter (DPA)
9-9
Understanding How the DPA Works
9-10
Why is the DPA Needed?
9-10
Can I Just Use SMDI?
9-10
What If I Cannot Use SMDI?
9-10
Choosing an Integration Mode
9-11
Using the Simple Integration Mode
9-11
Using the Hybrid Integration Mode
9-12
Using the Multiple Integration Mode
9-13
CHAPTER

10
Migration to an IP Telephony Network
10-1

Using the Hybrid Integration Mode
10-17
Using the Multiple Integration Mode
10-18
CHAPTER

11
CTI Applications Architecture and Design
11-1
Cisco CallManager Application Interfaces
11-1
CTI Architecture
11-3
Cisco CallManager Server
11-3
CTI Application Platform
11-4
CTI Devices
11-4
CTI Manager
11-5
CTI Manager Configuration
11-7
CTI Manager Provisioning
11-8

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System Profile
11-28
Design Assumptions
11-28
Design Approach
11-29
Identify CTI Resources
11-29
Calculate Package Weights for Each Application
11-29
Group the CTI Devices into Device Pools
11-31
Provision the CTI Resources on the Cisco CallManager and CTI Manager Servers
11-31
Provision Backup Servers for Failover Conditions
11-33
Summary
11-35
CHAPTER

12
Cisco IP IVR System Design Considerations
12-1
IP IVR Architecture
12-1
Cisco CallManager Device Weight Provisioning for IP IVR
12-2
Additional IP-IVR Scalability Considerations
12-3
IP IVR Co-Resident with Cisco CallManager

13-3
Redundancy Considerations
13-4
Bandwidth Provisioning Considerations
13-6
Call Admission Control
13-6
CHAPTER

14
Directory Access for Cisco IP Telephony Endpoints
14-1
Directory Access and Directory Integration
14-1
Configuring Directory Access
14-3
Directory Access for Cisco IP Phones
14-3
Directory Access for Cisco IP SoftPhone
14-5
Additional References
14-6
CHAPTER

15
Security Recommendations for IP Telephony
15-1
IP Telephony Security Guidelines
15-1
Establish Physical Security

15-8
Permitting Other Services
15-8
Protecting the VoIP Gateways
15-10
Firewalls
15-10
Secure the Cisco CallManager Server
15-12

Contents
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Turn off Unnecessary Services
15-12
Secure the NTFS File System
15-13
Enable System Auditing and Logging
15-14
Configure Certificate Authority
15-15
Secure the IIS Service
15-15
Enable Certificate Authentication Only
15-16
Enable W3C Extended Logging Format
15-16
Clear Indexing
15-16

16-1
Voice Management Overview
16-1
Voice Management Basics
16-1
CiscoWorks Voice Management Tools and Architecture
16-2
CiscoWorks IP Telephony Management Tools
16-2
Cisco Network Management Architecture
16-3
Deployment Considerations
16-4
Cisco CallManager Settings
16-4
System Requirements
16-5
Network Analysis Module Deployment
16-5
CiscoWorks Network Management Best Practices
16-6
Best Practices for Using CiscoWorks LAN Management Solution (LMS)
16-6
Best Practices for Using CiscoWorks VoIP Health Monitor (VHM)
16-7
Best Practices for Using CiscoWorks QoS Policy Manager (QPM)
16-8
Best Practices for Using CiscoWorks Service Level Manager (SLM)
16-8
Best Practices for Using CiscoWorks Internetwork Performance Monitor (IPM)

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Preface
Organization
Note
Cisco strongly recommends that you carefully read chapters 1, 2, and 3 before attempting to design an
IP telephony solution and before reading any other sections of this guide.
Chapter Title Description
1 Overview of Cisco AVVID
IP Telephony Solutions
Provides an overview of Cisco AVVID and some of the available Cisco
products for creating an IP telephony solution.
2 IP Telephony Deployment Models Describes the primary models used to deploy an IP telephony solution
and explains when to use each model.
Note
This guide makes frequent references to these deployment
models. Cisco recommends that you read this chapter carefully
and understand the main characteristics of each model.
3 Network Infrastructure Requirements
for IP Telephony
Describes key Quality of Service (QoS) features of the Cisco AVVID
network infrastructure and how they apply to IP telephony.
4 Choosing a Cisco IP Telephony
Gateway
Presents guidelines and recommendations on how to select the
appropriate gateways for your IP telephony network.
5 Transcoding, Conferencing, and MTP
Resources
Explains how Cisco CallManager handles media streams and describes

Cisco IP Phones and Cisco IP SoftPhone, with access to a corporate
LDAP directory.
15 Security Recommendations for
IP Telephony
Presents various considerations and options for securing your IP
telephony system.
16 Network Management
Recommendations for IP Telephony
Describes some of the tools available for managing your IP telephony
network.

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Preface
Obtaining Documentation
Obtaining Documentation
The following sections explain how to obtain documentation from Cisco Systems.
World Wide Web
You can access the most current Cisco documentation on the World Wide Web at the following URL:

Translated documentation is available at the following URL:
/>Documentation CD-ROM
Cisco documentation and additional literature are available in a Cisco Documentation CD-ROM
package, which is shipped with your product. The Documentation CD-ROM is updated monthly and may
be more current than printed documentation. The CD-ROM package is available as a single unit or
through an annual subscription.
Ordering Documentation
Cisco documentation is available in the following ways:
•

Cisco Technical Assistance Center (TAC) Web Site. Cisco.com registered users have complete access to
the technical support resources on the Cisco TAC Web Site.
Cisco.com
Cisco.com is the foundation of a suite of interactive, networked services that provides immediate, open
access to Cisco information, networking solutions, services, programs, and resources at any time, from
anywhere in the world.
Cisco.com is a highly integrated Internet application and a powerful, easy-to-use tool that provides a
broad range of features and services to help you to
•
Streamline business processes and improve productivity
•
Resolve technical issues with online support
•
Download and test software packages
•
Order Cisco learning materials and merchandise
•
Register for online skill assessment, training, and certification programs
You can self-register on Cisco.com to obtain customized information and service. To access Cisco.com,
go to the following URL:

Technical Assistance Center
The Cisco TAC is available to all customers who need technical assistance with a Cisco product,
technology, or solution. Two types of support are available through the Cisco TAC: the Cisco TAC
Web Site and the Cisco TAC Escalation Center.
Inquiries to Cisco TAC are categorized according to the urgency of the issue:
•
Priority level 4 (P4)—You need information or assistance concerning Cisco product capabilities,
product installation, or basic product configuration.
•

level 2; these classifications are assigned when severe network degradation significantly impacts
business operations. When you contact the TAC Escalation Center with a P1 or P2 problem, a Cisco TAC
engineer will automatically open a case.
To obtain a directory of toll-free Cisco TAC telephone numbers for your country, go to the following
URL:
/>Before calling, please check with your network operations center to determine the level of Cisco support
services to which your company is entitled; for example, SMARTnet, SMARTnet Onsite, or Network
Supported Accounts (NSA). In addition, please have available your service agreement number and your
product serial number.

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Preface
Obtaining Technical Assistance
CHAPTER

1-1
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1
Overview of Cisco AVVID IP Telephony Solutions
IP telephony refers to the technology for transmitting voice communications over a network using
standards-based Internet Protocol (IP). The Cisco Architecture for Voice, Video, and Integrated Data
(AVVID) provides the infrastructure and feature set for creating a single converged network that can
handle voice, video, and data traffic simultaneously. Cisco AVVID provides this capability while
maintaining a high level of availability, quality of service (QoS), and security for your network.
Built on the Cisco AVVID Network Infrastructure, a Cisco AVVID IP Telephony solution delivers
high-quality IP voice and fully integrated communications by allowing data, voice, and video to be
transmitted over a single network infrastructure. Leveraging the framework provided by Cisco AVVID,

Chapter 1 Overview of Cisco AVVID IP Telephony Solutions
Why IP Telephony?
Cisco provides an end-to-end IP network solution based on open standards, with an established portfolio
of applications and an ecosystem of partners to support your transition. The Cisco AVVID IP Telephony
solution is the leading converged network telephony solution for organizations that want to increase
productivity and reduce costs associated with managing and maintaining separate voice and data
networks. The flexibility and sophisticated functionality of the Cisco AVVID Network Infrastructure
provides the framework that permits rapid deployment of emerging applications such as desktop IP
telephony, unified messaging, desktop collaboration, enterprise application integration with IP phone
displays, and collaborative IP contact centers. These applications enhance productivity and increase
enterprise revenues.
Figure 1-1 illustrates a typical IP telephony solution employing the Cisco AVVID network
infrastructure, with Cisco CallManager as the call processing agent.
Figure 1-1 Typical IP Telephony Solution
IP IP
IP IP
IP IP
M
M
M M
M
M M
M
V
V
GK
Headquarters
Applications
(Voice mail, IVR, ICD, ...)
Branch

•
Communication endpoints
A communication endpoint is a user instrument — either a desk phone or even a software phone
application that runs on a PC. In the IP environment, each phone has an Ethernet connection. IP
phones have all functions you expect from a telephone as well as more complicated features, such
as the ability to access World Wide Web sites. Typical user instruments include Cisco IP Phones and
Cisco IP SoftPhones.
•
Call processing agent
At the heart of the IP telephony system is Cisco CallManager, the call processing agent.
Cisco CallManager software extends enterprise telephony features and capabilities to packet
telephony network devices such as IP phones, media processing devices, voice-over-IP (VoIP)
gateways, and multimedia applications. Additional data, voice, and video services such as unified
messaging, multimedia conferencing, collaborative contact centers, and interactive multimedia
response systems interact with the IP telephony solution through Cisco CallManager's open
telephony application programming interfaces (APIs).
•
Applications
As defined by Cisco AVVID, applications are physically independent from the call processing and
voice processing infrastructure, and they may reside anywhere within your network Applications
improve the end-to-end capabilities of the Cisco AVVID IP Telephony solution by adding
sophisticated telephony and converged network features, such as the following:
–
Cisco IP SoftPhone
–
Extension mobility
–
Multi-party voice conferencing
–
Unified messaging

Telephony solution includes quality-of-service (QoS) features such as classification, queuing, traffic
shaping, compressed Real-Time Transport Protocol (cRTP), and Transmission Control Protocol (TCP)
header compression.
The QoS components of the Cisco AVVID IP Telephony solution are provided through the rich IP traffic
management, queueing, and shaping capabilities of the Cisco AVVID Network Infrastructure. Key
elements of this infrastructure that enable QoS for IP telephony include:
•
Traffic marking
•
Enhanced queuing services (Catalyst 3500 and 4000 switches)
•
Link fragmentation and interleaving (LFI)
•
Compressed RTP (cRTP)
•
Low latency queuing (LLQ)
•
Link efficiency
•
Traffic shaping
•
Call admission control
Network Management
The Cisco AVVID Network Infrastructure offers a number of network management, QoS, and security
management tools that support the IP Telephony solution. CiscoWorks2000 includes a number of
network management tools to manage the operations, administration, and maintenance of IP telephony
networks. Cisco CallManager also offers enhanced software and configuration management tools that
leverage the strength and flexibility of IP networks. The Cisco CallManager user interface simplifies the
most common subscriber and telephony configuration tasks by building upon legacy telephony
administration systems and adding software and web-based applications.

Cisco CallManager cluster for redundancy and system scaling
•
Inline power to IP phone sets
•
Single cable for connecting both IP phone and PC
•
Quality of service from the desktop
•
IP addressing for easy adds, moves, and changes
Multi-Site WAN Model with Centralized Call Processing
In the multi-site WAN model with centralized call processing, the Cisco CallManager cluster resides at
the main (or central) campus, and communication with remote branch offices normally takes place over
the IP WAN. If either the central site or the IP WAN is down, the remote sites can continue to have
service through a feature called Survivable Remote Site Telephony (SRST), which runs on Cisco IOS
gateways. The remote sites can also place calls over the PSTN if the IP WAN is temporarily
oversubscribed. Each central site can support up to 10,000 users, and you can interconnect a number of
central sites with intercluster trunks.
In summary, the multi-site WAN model with centralized call processing has the following
characteristics:
•
Support for 10,000 users per central site
•
Cisco CallManager and voice mail at the central site
•
Centralized dial plan and administration
•
Call admission control based on locations, to protect voice quality of IP WAN calls

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Cisco IP Telephony Solution Reference Network Design Guide

Cisco CallManager servers and a maximum of 5000 or 2500 IP phones per site, respectively. This
model allows for up to 10,000 IP phones in the two-site configuration and 7,500 IP phones in the
three-site configuration.
•
Remote failover deployment model
Remote failover allows you to deploy the backup servers over the WAN. Using this deployment
model, you may have up to six sites with Cisco CallManager subscribers and one or two sites
containing the Cisco CallManager backup servers. This deployment allows for up to 10,000 IP
phones shared over the required number of sites.
The key advantages of clustering over the WAN are:
•
Single point of administration for IP phones for all sites within the cluster
•
Feature transparency
•
Shared line appearances
•
Extension mobility within the cluster
•
Unified dial plan
These advantages make clustering over the WAN well suited as a disaster recovery plan for business
continuance sites or as a single solution for small or medium sites. For further information on clustering
over the WAN, refer to the chapter on Call Processing with Cisco CallManager.

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Chapter 1 Overview of Cisco AVVID IP Telephony Solutions
Applications
Applications

long-distance toll charges.
For more information about Cisco IP SoftPhone, refer to the product literature at
/>ndex.htm
Extension Mobility
The Cisco CallManager Extension Mobility feature allows users within a Cisco CallManager cluster to
configure any Cisco IP Phone 7960 or 7940 as their own, temporarily, by logging in to that phone. Once
logged in, the phone adopts the user's personal phone number(s), speed dials, services links and other
user-specific properties. After logout, the phone adopts the original user profile.
With Cisco CallManager Extension Mobility, several employees can share office space on a rotational
basis instead of having a designated office. This approach is commonly used in work environments such
as sales offices and consulting firms where employees do not routinely conduct business in the same
place or keep the same hours every day.
For more information on Extension Mobility, refer to the documentation at
/>