Cisco Systems. Implementing Cisco Voice Gateways and Gatekeepers. Volume 2. Student

376 Pages·34.464 MB·English

GWGK
Implementing Cisco
Voice Gateways and
Gatekeepers
Volume 2
Version 2.0

Student Guide

Text Part Number: 97-2435-01
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Table of Contents
Volume 2
Advanced Gateway Features 4-1
Overview 4-1
Module Objectives 4-1
Implementing SRST Gateways 4-3
Overview 4-3
Objectives 4-3
Overview of SRST Gateways 4-4
Example: SRST Functionality 4-7
SRST Features and Capabilities 4-8
SRST Operation Process 4-12
SRST and Voice Mail 4-14
Integration via PRI Circuits 4-15
Integration via Analog Circuits 4-15
Basic SRST Commands 4-16
Optional SRST Commands 4-20
Configuring SRST for SCCP Support 4-25
Configuring Additional SRST Features for SCCP 4-30
Reference 4-31
SIP SRST Commands 4-33
Configuring SIP SRST 4-38
Verifying SRST Operation 4-43
Summary 4-46
Implementing Media Resources Using Cisco IOS Gateway DSPs 4-47
Overview 4-47
Objectives 4-47
Media Resources on Cisco IOS Gateways 4-48
DSP Requirements 4-52
Resource Allocation on the NM-HDV (C549-Based Hardware) 4-52
Resource Allocation on the NM-HDV2, NM-HD-xx, and PVDM2 (C5510-Based Hardware) 4-52
Cisco Unified CallManager and Media Resources 4-62
SCCP Configuration Commands for Enhanced Media Resources 4-64
DSP Farm Configuration Commands for Enhanced Media Resources 4-69
Configuring Cisco Unified CallManager-Controlled Enhanced Media Resources 4-72
Verifying Cisco Unified CallManager-Controlled Media Resources 4-80
Summary 4-85
Implementing Fax and Modem Support on Cisco IOS Gateways 4-87
Overview 4-87
Objectives 4-87
Transporting Modulated Data over IP Networks 4-88
Differences from Fax Transmission in the PSTN 4-88
Fax Services over IP Networks 4-89
Understanding Fax and Modem Pass-Through 4-90
Fax Pass-Through 4-90
Modem Pass-Through 4-91
Understanding FAX and Modem Relay 4-94
Fax Relay 4-94
Modem Relay 4-95
Modem Tone Detection and Signaling 4-97
Relay Switchover 4-98
Payload Redundancy 4-98
Dynamic and Static Jitter Buffers 4-98
Gateway-Controlled Modem Relay 4-98
Gateway Signaling Protocols with Fax and Modem Pass-Through and Relay 4-100
Gateway-Controlled MGCP T.38 Fax Relay 4-106
CA-Controlled MGCP T.38 Fax Relay 4-106
Understanding Store-and-Forward Fax 4-107
Configuring Fax Pass-Through and Relay with Dial Peers 4-108
Example: H.323 Fax Pass-Through Configuration 4-111
Example: H.323 Fax Relay Configuration 4-112
Configuring FAX Pass-Through and Relay with MGCP Gateways 4-113
Example: MGCP T.38 Fax Configuration 4-118
Cisco Unified CallManager Interaction and Restriction 4-119
Example: Cisco Unified CallManager, MGCP, and T.38 Fax 4-120
Summary 4-122
Implementing Call Applications on Cisco IOS Gateways 4-123
Overview 4-123
Objectives 4-123
Call Applications Overview 4-124
Introducing Tcl 4-126
Call Application Syntax Changes 4-129
Call Application Commands 4-132
Configuring Call Applications 4-135
Verifying Call Applications 4-148
Summary 4-153
Module Summary 4-154
Module Self-Check 4-155
Module Self-Check Answer Key 4-156
Gatekeeper Deployments 5-1
Overview 5-1
Module Objectives 5-1
Introducing Cisco Gatekeepers 5-3
Overview 5-3
Objectives 5-3
Cisco Gatekeeper Overview 5-4
Zones 5-8
Zone Prefixes 5-8
Technology Prefixes 5-9
Technology Prefix with Hopoff 5-9
Example of a Forced Technology Prefix Hopoff 5-10
Gatekeeper Hardware and Software Requirements 5-11
Gatekeeper Signaling 5-12
Admission Request Message Failures 5-20
Directory Gatekeepers 5-30
Additional Considerations for Using Directory Gatekeepers 5-30
Technology Prefix 5-35
Gatekeeper Address Resolution Process 5-37
Gatekeeper Call Routing 5-39
Gatekeeper Transaction Message Protocol 5-45
Summary 5-47
Implementing Basic Gatekeeper Functionality 5-49
Overview 5-49
Objectives 5-49
Single Gatekeeper—Multizone Configuration Scenario 5-50
Gatekeeper Configuration Steps 5-54
Configuring Zone Prefixes 5-55
Configuring Technology Prefixes 5-58
Registering Gateways 5-61
Dial Peer Configuration 5-67
ii Implementing Cisco Voice Gateways and Gatekeepers (GWGK) v2.0 © 2006 Cisco Systems, Inc.
Preventing Ephone and Dial-Peer Registration 5-69
Registering a Cisco Unified CallManager Cluster 5-72
Verifying Basic Gatekeeper Functionality 5-79
Summary 5-82
Implementing Gatekeeper-Based CAC 5-83
Overview 5-83
Objectives 5-83
Gatekeeper Zone Bandwidth Operation 5-84
Gatekeeper in Cisco Unified CallManager Networks 5-86
Zone Bandwidth Calculation 5-88
Zone Bandwidth Configuration 5-91
Verifying Zone Bandwidth Operation 5-95
RAI in Gatekeeper Networks 5-96
RAI Configuration 5-98
RAI Command 5-100
Verifying RAI Operation 5-101
Summary 5-105
Implementing Advanced Gatekeeper Functionality 5-107
Overview 5-107
Objectives 5-107
Multiple Gatekeepers 5-108
Interconnecting Gatekeepers 5-110
Configuring Directory Gatekeepers 5-116
Restricting Gatekeeper Registration 5-122
Example: Zone Subnet Configuration 5-126
Verifying Advanced Gatekeeper Functionality 5-127
Summary 5-133
Implementing Gatekeeper Redundancy 5-135
Overview 5-135
Objectives 5-135
Gatekeeper Redundancy Options 5-136
Comparing HSRP with Gatekeeper Clusters 5-144
Configuring Gatekeeper HSRP 5-145
GUP Configuration Commands 5-150
Configuring a GUP Gatekeeper Cluster 5-151
Verifying Gatekeeper Clustering Operation 5-153
Summary 5-154
Module Summary 5-155
References 5-155
Module Self-Check 5-157
Module Self-Check Answer Key 5-159
IP-to-IP Gateway Enterprise Deployments 6-1
Overview 6-1
Module Objectives 6-1
Introducing IP-to-IP Gateways 6-3
Overview 6-3
Objectives 6-3
IP-to-IP Gateway Functionality 6-4
Cisco IOS Image Support for IP-to-IP Gateways 6-6
IP-to-IP Gateways in Enterprise Environments 6-7
Protocol Interworking on IP-to-IP Gateways 6-12
Media Flows on IP-to-IP Gateways 6-14
Codec Filtering on IP-to-IP Gateways 6-17
RSVP-Based CAC on IP-to-IP Gateways 6-19
IP-to-IP Gateways and Gatekeeper Interworking 6-21
© 2006 Cisco Systems, Inc. Implementing Cisco Voice Gateways and Gatekeepers (GWGK) v2.0 iii
IP-to-IP Gateway Call Flows 6-23
Summary 6-30
Implementing IP-to-IP Gateways 6-31
Overview 6-31
Objectives 6-31
Protocol Interworking Command 6-32
Configuring H.323-to-H.323 Interworking 6-33
Configuring H.323-to-SIP Interworking 6-37
Media Flow and Transparent Codec Commands 6-41
media 6-41
codec transparent 6-41
Configuring Transparent Codec Pass-Through and Media Flow-Around 6-42
Configuring IP-to-IP Gateways and Via-Zone Gatekeepers 6-44
Verifying IP-to-IP Gateways and Via-Zone Gatekeepers 6-47
Summary 6-50
Module Summary 6-51
Module Self-Check 6-52
Module Self-Check Answer Key 6-53

iv Implementing Cisco Voice Gateways and Gatekeepers (GWGK) v2.0 © 2006 Cisco Systems, Inc.
Module 4
Advanced Gateway Features
Overview
Cisco IOS gateways offer a variety of advanced features that allow a gateway to be more than
just an interconnection and routing device for basic telephony. Because these features are
intended to meet customers’ requirements and are necessary in order to fully integrate all
common telephony functions into an IP environment, administrators need to know what they
are and how to implement them.
Module Objectives
Upon completing this module, you will be able to describe and implement advanced gateway
features on Cisco IOS voice gateways. This ability includes being able to meet these objectives:
(cid:132) Implement SRST for SIP and SCCP phones on Cisco IOS gateways
(cid:132) Implement conferencing and transcoding using DSP resources
(cid:132) Design and implement fax services within a Cisco Unified IP Communications network
(cid:132) Download and implement a sample Tcl script on a Cisco IOS gateway
4-2 Implementing Cisco Voice Gateways and Gatekeepers (GWGK) v2.0 © 2006 Cisco Systems, Inc.
Lesson 1
Implementing SRST Gateways
Overview
Cisco Unified Survivable Remote Site Telephony (SRST) provides Cisco Unified CallManager
with fallback support for Cisco IP phones that are attached to your remote networks. Cisco
Unified SRST enables routers to provide call-handling support for Cisco IP phones when they
lose connection to remote primary, secondary, or tertiary Cisco Unified CallManagers, or when
the WAN connection to where the Cisco Unified CallManager is located is down.
Objectives
Upon completing this lesson, you will be able to implement SRST for session initiation
protocol (SIP) and Skinny Client Control Protocol (SCCP) phones on Cisco IOS gateways.
This ability includes being able to meet these objectives:
(cid:132) Describe the advantages and disadvantages of how SRST can support remote sites with
fallback telephony services for both SCCP and SIP
(cid:132) Describe which features are supported by SRST, where to get updated information and
contrast features with Cisco Unified CallManager
(cid:132) Describe how SRST is activated on a Cisco IOS gateway and how endpoints register with
the gateway
(cid:132) Describe the commands necessary to configure SRST
(cid:132) Configure an SRST gateway to support phones and basic call features
(cid:132) Configure an SRST gateway to provide additional features, including conferencing
(cid:132) Configure an SIP SRST gateway to provide basic call features
(cid:132) Verify correct SRST operation
Overview of SRST Gateways

This topic gives an overview of Cisco IOS-based SRST gateways.
Overview of SRST Gateways
SRST functionality:
• SRST offers basic phone functionality for remote sites to
guard against outage of centralized Cisco Unified
CallManager because of
– WAN failure
– Server breakdown
• Different feature sets for SCCP and SIP SRST
– SRST for SCCP phones developed over years
©2006 Cisco Systems, Inc. All rights reserved. GWGK v2.0—4-2
Cisco Unified CallManager supports Cisco IP phones at remote sites connected via Cisco
multiservice routers across the WAN. Prior to Cisco Unified SRST, when the WAN connection
between a router and the Cisco Unified CallManager failed or when connectivity with Cisco
Unified CallManager was lost for some reason, Cisco IP phones on the network became
unusable for the duration of the failure. Cisco Unified SRST overcomes this problem and
ensures that the Cisco IP phones offer continuous (although limited) service by providing call-
handling support for Cisco IP phones directly from the Cisco Unified SRST router. The system
automatically detects a failure and uses Simple Network-Enabled Auto Provision (SNAP)
technology to autoconfigure the branch office router to provide call processing for Cisco IP
phones that register with the router. When the WAN link or connection to the primary Cisco
Unified CallManager is restored, call handling reverts back to the primary Cisco Unified
CallManager.
When Cisco IP phones lose contact with primary, secondary, and tertiary Cisco Unified
CallManagers, they must establish a connection to a local Cisco Unified SRST router to sustain
the call-processing capability necessary to place and receive calls. The Cisco IP phone retains
the IP address of the local Cisco Unified SRST as a Cisco Unified CallManager IP address
within its configuration. The Settings menu supports a maximum of five Cisco Unified
CallManager servers. When the last Cisco Unified CallManager within the list is not available
on the network, the local Cisco Unified SRST router's IP address is retained as the standby
connection for Cisco Unified CallManager.
4-4 Implementing Cisco Voice Gateways and Gatekeepers (GWGK) v2.0 © 2006 Cisco Systems, Inc.