Nortel Networks Remote Gateway 50 User Manual
Title page
Nortel Communication Server 1000
Nortel Communication Server 1000 Release 4.5
Main Office Configuration for Survivable
Remote Gateway 50
Configuration Guide
Document Number: 553-3001-207
Document Release: Standard 2.00
Date: January 2006
Year Publish FCC TM
Copyright © Nortel Networks Limited 2006
All Rights Reserved
Produced in Canada
Information is subject to change without notice. Nortel Networks reserves the right to make changes in design
or components as progress in engineering and manufacturing may warrant.
Nortel, Nortel (Logo), the Globemark, This is the Way, This is Nortel (Design mark), SL-1, Meridian 1, and
Succession are trademarks of Nortel Networks.
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Revision history
January 2006
Standard 2.00. This document is up-issued for CR Q01202736, with
information on reconfiguring Call Server alarm notification levels if
necessary when configuring Adaptive Network Bandwidth Management. See
pages 76 and 84.
August 2005
Standard 1.00. This document is a new document to support
Communication Server 1000 Release 4.5.
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 4 of 258 Revision history
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Contents
List of procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 9
About this document . . . . . . . . . . . . . . . . . . . . . . . 11
Subject .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Applicable systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Conventions .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Related information .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Contents .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Survivable Remote Gateway .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Main office hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Main office requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Optional features to enhance SRG functionality .. . . . . . . . . . . . . . . . . 21
Normal Mode and Local Mode overview . . . . . . . . . . . . . . . . . . . . . . . 22
Bandwidth Management Overview .. . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Capacity .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Branch office dialing plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Cross reference for branch office and SRG50 terminology . . . . . . . . . 32
Setting up the main office . . . . . . . . . . . . . . . . . . . 35
Contents .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
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SRG information required by the main office . . . . . . . . . . . . . . . . . . . 36
Main office information required by the SRG . . . . . . . . . . . . . . . . . . . 37
Zone parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Branch office IP Phone configuration at the main office . . . . . . . . . . . 46
Bandwidth Management . . . . . . . . . . . . . . . . . . . . 49
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Introduction .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Codec negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Configuring Bandwidth Management parameters . . . . . . . . . . . . . . . . 56
Adaptive Network Bandwidth Management . . . . . . . . . . . . . . . . . . . . 67
Tandem Bandwidth Management overview . . . . . . . . . . . . . . . . . . . . . 93
Dialing Plan Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Network using Uniform Dialing Plan . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Network using Coordinated Dialing Plan .. . . . . . . . . . . . . . . . . . . . . . 122
Alternative Call Routing for Network Bandwidth
Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Operating parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Feature interactions .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Feature packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Feature implementation using Command Line Interface . . . . . . . . . . . 149
Feature implementation using Element Manager . . . . . . . . . . . . . . . . . 151
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Feature operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Dialing Plan configuration . . . . . . . . . . . . . . . . . . . 167
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Overview .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
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On-net dialing plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Off-net dialing plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Routing calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
H.323 zones .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Zone-based digit manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Configuring PSTN access for SRG users in Normal Mode . . . . . . . . . 173
Dialing plan examples .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Emergency Services configuration . . . . . . . . . . . . 225
Contents .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Emergency Services Access (ESA) .. . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Configuring the NRS for ESA SPN . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Testing the ESDN number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Configuring ESA using Element Manager . . . . . . . . . . . . . . . . . . . . . . 239
Emergency Service using Special Numbers (SPN) .. . . . . . . . . . . . . . . 239
Enhanced UNIStim Firmware Download . . . . . . . . 241
Contents .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Firmware upgrade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Appendix A: Media Redirection Scenarios . . . . . . 245
List of terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
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List of procedures
Procedure 1
Configuring ESN and SRG zones . . . . . . . . . . . . . . . . . 40
Procedure 2
Configuring branch office IP Phones at the
main office using LD 11 . . . . . . . . . . . . . . . . . . . . . . . . . 47
Procedure 3
Printing intrazone and interzone statistics for
a zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Procedure 4
Displaying CAC parameters for one or more
zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Procedure 5
Provisioning Tandem Bandwidth Management . . . . . .110
Procedure 6
Accessing the Zones web page . . . . . . . . . . . . . . . . . . . 152
Procedure 7
Printing zone ALTPrefix . . . . . . . . . . . . . . . . . . . . . . . . . 157
Procedure 8
Show Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160
Procedure 9
Enabling a zone’s branch office behavior . . . . . . . . . .163
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 10 of 258 List of procedures
Procedure 10
Suppress Alternative Call Routing for
NBWM alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Procedure 11
Configuring the main office . . . . . . . . . . . . . . . . . . . . . . 175
Procedure 12
Configuring the NRS database . . . . . . . . . . . . . . . . . . . 184
Procedure 13
Configuring the branch office . . . . . . . . . . . . . . . . . . . . 187
Procedure 14
Testing PSTN access using an SRG IP Phone . . . . . . . 192
Procedure 15
Configuring the main office . . . . . . . . . . . . . . . . . . . . . . 231
Procedure 16
Configuring the branch office zone . . . . . . . . . . . . . . . . 237
Procedure 17
Testing ESDN using an SRG telephone . . . . . . . . . . . . 238
Procedure 18
Upgrading firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
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About this document
This document is a global document. Contact your system supplier or your
Nortel representative to verify that the hardware and software described are
supported in your area.
Subject
This document describes the Main Office Configuration for the Survivable
Remote Gateway 50: Configuration Guide (553-3001-207). Information in
this document complements information found in documents in the
Communication Server 1000 documentation suite, as listed in “Related
information” on page 13.
For information about how to configure the SRG50, see SRG50
Configuration Guide at http://www.nortel.com. Select Support &
Training > Technical Documentation Communication Servers >
Enterprise Communication Servers > Communication Server 1000S and
search for SRG.
Note on legacy products and releases
This NTP contains information about systems, components, and features that
are compatible with Nortel Communication Server 1000 Release 4.5
software. For more information about legacy products and releases, click the
Technical Documentation link under Support & Training on the Nortel
home page:
http://www.nortel.com
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 12 of 258 About this document
Applicable systems
This document applies to the following systems:
• Communication Server 1000S (CS 1000S)
• Communication Server 1000M Chassis (CS 1000M Chassis)
• Communication Server 1000M Cabinet (CS 1000M Cabinet)
• Communication Server 1000M Half Group (CS 1000M HG)
• Communication Server 1000M Single Group (CS 1000M SG)
• Communication Server 1000M Multi Group (CS 1000M MG)
• Communication Server 1000E (CS 1000E)
Note: When upgrading software, memory upgrades may be required on
the Signaling Server, the Call Server, or both.
Intended audience
This document is intended for individuals responsible for configuring the
main office for Survivable Remote Gateway for organizations using CS 1000
systems.
Conventions
Terminology
In this document, the following systems are referred to generically as
“system”:
• Communication Server 1000S (CS 1000S)
• Communication Server 1000M (CS 1000M)
• Communication Server 1000E (CS 1000E)
•Meridian1
The following systems are referred to generically as “Small System”:
• Communication Server 1000M Chassis (CS 1000M Chassis)
553-3001-207 Standard 2.00 January 2006
• Communication Server 1000M Cabinet (CS 1000M Cabinet)
The following systems are referred to generically as “Large System”:
• Communication Server 1000M Half Group (CS 1000M HG)
• Communication Server 1000M Single Group (CS 1000M SG)
• Communication Server 1000M Multi Group (CS 1000M MG)
Related information
This section lists information sources that relate to this document.
NTPs
The following NTPs are referenced in this document:
• Converging the Data Network with VoIP (553-3001-160)
• Electronic Switched Network: Signaling and Transmission Guidelines
(553-3001-180)
• Dialing Plans: Description (553-3001-183)
• Signaling Server: Installation and Configuration (553-3001-212)
About this document Page 13 of 258
• IP Peer Networking: Installation and Configuration (553-3001-213)
• Branch Office: Installation and Configuration (553-3001-214)
• Optivity Telephony Manager: Installation and Configuration
(553-3001-230)
• Software Input/Output: Administration (553-3001-311)
• Emergency Services Access: Description and Administration
(553-3001-313)
• Optivity Telephony Manager: System Administration (553-3001-330)
• Element Manager: System Administration (553-3001-332)
• IP Line: Description, Installation, and Operation (553-3001-365)
• ISDN Primary Rate Interface: Features (553-3001-369)
• Basic Network Features (553-3001-379)
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 14 of 258 About this document
• SRG50 Configuration Guide
• Communication Server 1000M and Meridian 1: Small System Planning
and Engineering (553-3011-120)
• Communication Server 1000M and Meridian 1: Large System Planning
and Engineering (553-3021-120)
• Communication Server 1000S: Planning and Engineering
(553-3031-120)
• Communication Server 1000E: Planning and Engineering
(553-3041-120)
• Software Input/Output: Maintenance (553-3001-511)
Online
To access Nortel documentation online, click the Technical Documentation
link under Support & Training on the Nortel home page:
http://www.nortel.com
CD-ROM
To obtain Nortel documentation on CD-ROM, contact your Nortel customer
representative.
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Overview
Contents
This section contains information about the following topics:
Survivable Remote Gateway. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Main office hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Main office requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Optional features to enhance SRG functionality. . . . . . . . . . . . . . . . . . 21
Normal Mode and Local Mode overview . . . . . . . . . . . . . . . . . . . . . . . 22
Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Branch office dialing plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Cross reference for branch office and SRG50 terminology . . . . . . . . . 32
Survivable Remote Gateway
The Survivable Remote Gateway (SRG) extends CS 1000 features from a
main office to one or more remote SRG locations (branch offices). The
SRG50 Release 1.0 operates with the CS 1000 running Release 4.5 and is
backward compatible to Release 3.0 and Release 4.0. SRG does not operate
with CS 1000 Release 1.0 and Succession 1000 2.0 systems.
In addition to the SRG 1.0 model, which is positioned as the lower cost
alternative to the Media Gateway 1000B product, there is a new “mini” model
for the smaller branch office, known as the SRG50. The SRG50 is optimized
for the 5-32 user branch office.
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 16 of 258 Overview
The SRG is implemented on a BCM50 platform and is connected to a
CS 1000 at the main office over a LAN or a WAN. This configuration allows
the call processing for the IP Phones at the SRG site to be centralized at the
main office. The Call Server at the main office provides the call processing
for the IP Phones in both the main office and branch offices. The SRG
provides call processing functionality to telephones in local mode and local
analog devices. The SRG also provides digital and analog trunk access to the
local Public Switched Telephone Network (PSTN).
In order for devices in the CS 1000 network to access analog devices at the
SRG or to access the PSTN at the SRG, virtual trunks are used over the LAN/
WAN.
If the main office fails to function, or if there is a network outage, the SRG
provides service to the telephones located at the branch office. This enables
the IP Phones to survive the outage between the branch office and the main
office.
The SRG is designed to work with a main office only if the main office and
the SRG use a common dialing plan. Any other configuration is not
guaranteed to work reliably. Since the Call Server and the SRG handle dialing
slightly differently, ensure that any settings you use for the main office, that
need to interact with the SRG, can be accommodated by the SRG call
processing.
Figure 1 on page 17 shows the networking among the main office, SRG, and
IP Phones.
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Figure 1:
SRG network
Main office hardware description
The main office must be one of the following systems:
Overview Page 17 of 258
• CS 1000S
• CS 1000E
• CS 1000M Cabinet
• CS 1000M Chassis
• CS 1000M HG
• CS 1000M SG
• CS 1000M MG
Note: Throughout this document, references to CS 1000 systems
encompass all CS 1000 system types.
The diagrams throughout this documentation show a CS 1000S main office.
All of the systems appearing in the list perform identical main office
functions as far as the SRG is concerned. For information about the SRG,
refer to SRG50 Configuration Guide.
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 18 of 258 Overview
Signaling Server
The Signaling Server is required at the main office only. It provides the
following functions:
• Terminal Proxy Server (TPS)
— The TPS provides a connection from the IP Phones to the Call
• Web server for Element Manager and Network Routing Service (NRS)
Manager
A second Signaling Server can be used to provide redundancy in the case of
failure in the primary Signaling Server at the main office.
A similar function to the Signaling Server exists at the SRG.
The Signaling Server supports both en bloc and overlap signaling. En bloc
signaling is standard. If overlap signaling is to be used, Nortel recommends
that it be installed and enabled on all Signaling Servers in the network. Failure
to do so results in delays in call completion due to overlap to en bloc
conversion.
Server. It also provides a connection path from a virtual trunk to the
Call Server.
For more information about the Signaling Server, refer to Signaling Server:
Installation and Configuration (553-3001-212). For more information about
H.323 and overlap signaling, refer to IP Peer Networking: Installation and
Configuration (553-3001-213).
Network Routing Service
• The NRS application provides network-based routing, combining the
following into a single application:
• H.323 Gatekeeper — provides central dialing plan management and
routing for H.323-based endpoints and gateways.
Note: NRS also contains SIP Redirect Server but SIP Trunks are not
supported on an SRG.
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Overview Page 19 of 258
• NRS Database — stores the central dialing plan in XML format for the
H.323 Gatekeeper. The H.323 Gatekeeper accesses this common
endpoint and gateway database.
• Network Connect Server (NCS) — used only for Media Gateway
1000B (MG 1000B), SRG, Geographic Redundancy and Virtual Office
solutions. The NCS allows the Line TPS (LTPS) to query the NRS using
the UNIStim protocol.
• NRS Manager web interface — the NRS provides its own web
interface to configure the H.323 Gatekeeper and the NCS.
The NRS application provides routing services to H.323 devices. The H.323
Gatekeeper can be configured to support H.323 routing services. The H.323
Gatekeeper can reside on the same Signaling Server.
Each system in an IP Peer network must register to the NRS. The NRS
software identifies the IP addresses of systems based on the network-wide
numbering plan. NRS registration eliminates the need for manual
configuration of IP addresses and numbering plan information at every site.
When configuring the NRS it is necessary to enable the NCS. Ensure that the
check box “Network Connection Server enabled” is checked in the NRS
configuration window of CS 1000 Element Manager.
For information about configuring the NRS, refer to IP Peer Networking:
Installation and Configuration (553-3001-213).
Telephones
The SRG supports the following telephones:
• IP Phone 2001
• IP Phone 2002
• IP Phone 2004
• IP Phone 2007
• IP Softphone 2050
• Mobile Voice Client (MVC) 2050
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
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• Analog (500/2500-type) telephones
• WLAN Handset 2210/2211
Note: Throughout this document, the IP Phones in this list are referred
to collectively as IP Phones.
Main office requirements
The branch office requires the following at the main office:
• CS 1000 hardware, running Succession 3.0, CS 1000 Release 4.0, or
CS 1000 Release 4.5.
• IP Peer H.323 Trunk (H323_VTRK) package 399. This package is
required to support H.323 functionality. Package 184 is included with
package 399.
• The main office must have a software Service Level of 2 or higher to
work with the branch office.
• Ensure that you have ordered enough IP user and Virtual Trunk licenses
at the main office to support the SRG50 or the capacity of your branch
office.
The main office requires the following software packages to support the
specified Basic Network features. Refer to Basic Network Features (5533001-379) for more information about these features.
• Network Call Back Queuing (MCBQ) package 38. This package is
required for SRG IP Phones to invoke any queuing feature or ringback
when free.
• Network Speed Call (NSC) package 39. This package is required for
SRG IP Phones to invoke the Network Speed Call feature.
The main office requires the following software packages to support the
specified ISDN Primary Rate Interface features. Refer to ISDN Primary Rate
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Overview Page 21 of 258
Interface: Features (553-3001-369) for more information about these
features.
• Network Attendant Service (NAS) package 159. This package is
required for analog (500/2500-type) telephones in the branch office to
access attendant services when the attendant is configured on the main
office.
• Network Message Services (NMS) package 175. This package is
required for analog (500/2500-type) telephones in the branch office to
share the voicemail system in the main office. For any configurations
using centralized CallPilot on the main office with one or more branch
offices in separate time zones, the NMS package is required at the main
office for the branch IP Phones.
Optional features to enhance SRG functionality
• Network Alternate Route Selection (NARS) package 58. Refer to Basic
Network Features (553-3001-379).
• Overlap Signaling (OVLP) package 184. This package is optional; it is
required for overlap signaling. It is packaged with H.323 Virtual Trunk
(H323_VTRK) package 399 (Release 4.0 only).
• Emergency Services Access (ESA) package 329. This package is
optional; it is required only to receive 911/ESA features in North
American and some Caribbean and Latin American (CALA) markets.
Refer to Emergency Services Access: Description and Administration
(553-3001-313).
• Virtual Office (VIRTUAL_OFFICE) package 382. This package is
optional; it is required only for Virtual Office functionality.
• Network Signaling (NSIG) package 37. This package is optional for
SRG IP Phones to access set-based Network Class of Service (NCOS)
features.
• Adaptive Network Bandwidth Management package 407.
• Alternative Call Routing for Network Bandwidth Management.
For software and hardware requirements for SRG, refer to SRG50
Configuration Guide.
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
Page 22 of 258 Overview
Normal Mode and Local Mode overview
Normal Mode
IP Phones that are physically located at the SRG but are registered with the
main office are in Normal Mode. The main office provides centralized call
processing for the SRG IP Phones. These telephones are registered to the
main office TPS and are controlled by the Call Server at the main office.
Users of the SRG IP Phones receive the features, key layout, and tones of the
main office Call Server. This provides feature and application transparency
between the branch office and the main office.
Local Mode
An IP Phone at the SRG may be in Local Mode for two different reasons;
1 IP Phone may have just booted up.
2 IP Phone cannot communicate to the main office because of a WAN
failure or a failure of the main office components.
Devices that are physically located with the SRG and are controlled by the
SRG system are said to be in Local Mode. These devices consist of analog
telephones, analog devices, such as, fax, and may include IP Phones.
Normally IP Phones are registered to the main office, in Normal Mode;
however, when the IP Phone cannot reach the main office, it reverts to Local
Mode.
IP Phone users in Normal Mode use the feature set on the main office. IP
Phone users in Local Mode receive only those features and tones that are
provisioned on the SRG. Users of analog (500/2500-type) telephones always
use the feature set on the SRG.
For information about the features supported in Local Mode, refer to SRG50
Configuration Guide.
Survivability
SRG provides survivability against WAN failure, main office Call Server
failure, main office Signaling Server failure, and Gatekeeper failure.
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Overview Page 23 of 258
SRG supports the Geographic Redundancy feature. For further information
about Geographic Redundancy, see Communication Server 1000: System
Redundancy (553-3001-307).
In the event of a WAN failure, the SRG IP Phones lose communication with
the main office. This causes the SRG IP Phones to reset and register with the
SRG. The IP Phones then operate in Local Mode, providing services based on
a limited SRG feature set, which has significant differences from the CS 1000
software. For further information about services and features supported on
the SRG, refer to SRG50 Configuration Guide.
If the main office Call Server fails and call processing services are provided
by an Alternate Call Server, the SRG IP Phones reset and reregister with the
Alternate Call Server and receive call processing services from it. If no
Alternate Call Server is available, the SRG IP Phones go to Local Mode while
the SRG attempts to find an Alternate Call Server by way of the NCS.
If the main office Signaling Server fails and an Alternate Signaling Server is
available, the SRG IP Phones reset and reregister with the SRG. The SRG will
then query the NCS for the Alternate Signaling Server’s IP address. The SRG
will redirect the IP Phone to the Alternate Signaling Server and continue to
receive call processing services from the main office Call Server. If no
Alternate Signaling Server is available, the SRG IP Phones reset and register
with the SRG in Local Mode.
When an IP Phone at the SRG first boots up, it attempts to communicate with
the SRG. After it establishes communications with the SRG, the SRG
redirects it to the main office. When the SRG IP Phone attempts to register
with the main office, the SRG first queries the Primary NRS (NCS) for the
main office Virtual Trunk node IP address to redirect the IP Phone. If the
Primary NRS (NCS) is down or unreachable, the SRG queries the
Alternate NRS (H.323 Gatekeeper), if one is specified. If it receives a
positive response, the SRG IP Phone is redirected to the specified main office.
Otherwise, if neither a Primary or an Alternate NRS (H.323 Gatekeeper) is
available, the SRG IP Phone remains in Local Mode, and receives call
processing services from the SRG until communication can be reestablished.
SRG IP Phones in Normal Mode remain registered with the main office if the
Primary NRS fails and no Alternate NRS is available. They can call any main
office telephone or IP Phones in Normal Mode in other branch offices.
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However, they cannot call any SRG analog (500/2500-type) telephones or
any external numbers through the SRG trunks because the Virtual Trunks are
not available. (SRG analog [500/2500-type] telephones are accessible if
alternate routing is available through the PSTN.)
Recovery to Normal Mode
If an IP Phone is in Local Mode due to WAN failure or main office
component failure, the SRG tries to communicate with the main office TPS
at regular intervals. Once communication is established with the main office
call server, the idle SRG IP Phones are automatically redirected and
reregistered to the main office. IP Phones that were busy at the time
communication was reestablished complete the call in Local Mode, and then
reregister with the main office after the call is complete.
Local Mode operation
When an SRG IP Phone is in Local Mode, the user has full access to the
services configured at the SRG (analog devices or analog or digital trunks)
and to other IP Phones registered to the SRG. In Local Mode, the IP Phones
can make local calls to other IP Phones and other analog (500/2500-type)
telephones at the branch office. They can also be used to make outgoing
PSTN calls and receive incoming calls as usual. SRG IP Phones can access
the main office IP Phones or other branches by routing through the local
PSTN.
When a telephone or trunk in the main office calls an SRG IP Phone that
has switched to Local Mode due to WAN failure, the call is treated
according to the main office call redirection configuration (such as
forwarding to voicemail or continuous ringback).
Testing the telephone in Local Mode
From Normal Mode, the branch user has the option of going to Local Mode
manually by resetting the telephone or using Test Local Mode. The test can
be performed by the user at any time and does not require a password. This
test is invoked from the IP Phone.
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IMPORTANT!
Nortel recommends testing Local Mode operation after changing the
provisioning for a telephone on the SRG.
To ensure that users do not forget to resume Normal Mode operation, the
SRG redirects the telephone to the main office to return the telephone to
Normal mode. This occurs if the telephone remains registered to the SRG in
Test Local Mode for ten minutes (default setting). Alternatively, the user can
press the Quit key
For further information about Local Mode functionality for SRG, refer to
SRG50 Configuration Guide.
Virtual Trunks
In order for endpoints in the CS1000 network to access endpoints in local
mode at the SRG or to access the PSTN at the SRG, Virtual Trunks are used
over the LAN/WAN.
Virtual Trunks are software components that provide the trunking features of
the Meridian Customer-Defined Network (MCDN) feature set. Access to
PSTN digital or analog trunks at the branch office occurs through the MCDN
Virtual Trunk.
Overview Page 25 of 258
from the set to return to Normal Mode.
X
For more information about Virtual Trunks, refer to IP Peer Networking:
Installation and Configuration (553-3001-213).
Note: Virtual Trunks are sometimes referred to as H.323 IP Peer Trunks.
In the SRG50 Configuration Guide, Virtual Trunks are referred to as IP
Trunks.
IP Phone calls
When an IP Phone calls another IP Phone, each telephone receives the
address of the other to exchange media directly between the telephones.
When in Normal Mode, an SRG IP Phone calling a main office IP Phone does
not require any trunking to set up the call. However, LAN/WAN bandwidth
is used to provide a media path for the call. For more information on Direct
IP media path functionality, see IP Peer Networking: Installation and
Configuration (553-3001-213).
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Bandwidth Management Overview
For a complete overview of Bandwidth Management, refer to the Converging
the Data Network with VoIP (553-3001-160), and for details on
configuration, refer to “Bandwidth Management” on page 49.
Network Bandwidth Management
Network Bandwidth Management allows for a limit to be placed on the
amount of interzone bandwidth allowed between IP Phones in Normal Mode
at the SRG and the rest of the CS 1000 network.
As well, it allows for the selection of interzone bandwidth codecs for calls
between the IP Phones in Normal Mode and the rest of the CS 1000 network.
Adaptive Network Bandwidth Management
Adaptive Network Bandwidth Management allows the system to dynamically
react to Quality of Service (QoS) degradation and take corrective action.
Network Bandwidth Management Zones
A zone is a collection of IP Phones that:
• share similar IP bandwidth restrictions
• are geographically close to one another
• are all in the same time zone
• are all in the same PSTN dialing plan
The Network Bandwidth Management Zone is made up of the VPNI and the
zone. The VPNI of the main office and all the SRG associated with it must be
the same.
Each SRG must have its own unique zone number and configured in the main
office Call Server and the SRG.
Note: Throughout this document, the term “zone” is defined as a
Bandwidth Management Zone, not an NRS (H.323 Gatekeeper) Zone.
Refer to “Bandwidth Management” on page 49.
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Miscellaneous items
Time of Day
Because the SRG IP Phones, in Normal Mode, receive their clock information
from the main office, which may be located in a different time zone, the main
office must be able to provide a different time of day for these phones.
The time zone of the SRG is configured with the SRG zone at the main office.
The time zone adjusts the main office time for display at the SRG. SRG
telephones then display the correct time of the SRG, rather than that of the
main office. For any configurations using centralized Call Pilot on the main
office with one or more branch offices in separate time zones, the NMS
package is required at the main office for the branch IP Phones.
SRG IP Phone to local PSTN calls
When an SRG IP Phone in Normal Mode dials a local PSTN number, the call
is processed by the main office Call Server. The dialed digits are modified
according to the dialing plan information configured in the zone for the SRG
IP Phone.
The call is configured to be routed over the Virtual Trunk to the branch office.
The SRG then tandems the call to the local PSTN.
Overview Page 27 of 258
Likewise, long distance calls can also be configured.
IMPORTANT!
If you use one Access Code for both local and long distance calls, and
that Access Code is associated with a branch office zone, all calls (local
and long distance) are routed through the SRG.
IP Phone to analog (500/2500-type) telephone calls
When an IP Phone in Normal Mode at the SRG calls an analog (500/2500type) telephone of the same SRG, the call is processed at the main office Call
Server. A Virtual Trunk route is selected according to the digits dialed. The
call is routed over a Virtual Trunk to the branch office. The SRG processes
the incoming Virtual Trunk call and terminates it to the local analog (500/
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2500-type) telephone. Since this is a call between IP and circuit-switched
devices, a DSP resource on a Media Card is allocated and connected to the
analog (500/2500-type) telephone. The IP address of the DSP resource is
returned to the main office Call Server so a direct media path between the
IP Phone and the DSP resource can be set up when the call is established.
Refer to IP Peer Networking: Installation and Configuration (553-3001-213)
for details.
Conference calls
When an SRG user initiates a conference call, the conference facilities of the
main office are used. This means that in a conference among three SRG users,
the LAN/WAN bandwidth of three media paths is used. The calls are
controlled by the main office, except in Local Mode. In Local Mode, SRG
users do not have access to conferencing.
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Capacity
Overview Page 29 of 258
Networking consideration
A fault condition can occur if IP Phones use a different route to the main
office than that used by the SRG.
CAUTION — Service Interruption
If the network is planned so that IP Phones use a different
route to the main office than that used by the SRG, a fault
condition can occur. When the SRG can ping the main
office but the IP Phone cannot ping the main office due to
a network outage, an IP Phone registration can force the
telephone into a cycle of registering locally, being
redirected to the main office, rebooting, and then
registering locally again. When this cycle occurs, further
diagnose the network outage.
Each CS 1000 main office can support up to 255 branch offices, which can be
made up of any combination of SRGs and MG 1000Bs. SRG50 supports up
to 32 IP Phone users. However, since all IP Phones register with the main
office, the governing factor is the maximum number of IP Phones that can be
supported at the main office. This means the total number of IP Phones in all
offices can be no greater than the capacity of the main office. Refer to one of
the following documents to determine the total number of phones your system
can support:
• Communication Server 1000S: Planning and Engineering (553-3031-
120)
• Communication Server 1000E: Planning and Engineering (553-3041-
120)
• Communication Server 1000M and Meridian 1: Large System Planning
and Engineering (553-3021-120)
• Communication Server 1000M and Meridian 1: Small System Planning
and Engineering (553-3011-120).
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Virtual Trunks capacity
The SRG capacity to support a number of simultaneous calls depends on the
specific codec type used.
In Normal Mode, the codec selection used is controlled by specific
programming of the CS 1000. In this case: SRG 505 supports up to a
maximum of 15 Virtual trunks unless both the intrazone and interzone codecs
are configured as Best Quality (G.711), in which case the maximum number
of Virtual Trunks would be 24.
In Local Mode, if the WAN has failed, there are no longer any Virtual Trunks
available between the SRG and CS 1000. However, the SRG will continue to
convert calls from IP terminals for communication through the PSTN. Nortel
recommends you use G.711 codec. In this case, if G.711 is used, the number
of simultaneous calls from IP terminals to the PSTN supportable is a
maximum of 24.
Branch office dialing plan
Since IP Phone users can be located at a branch office equipped with an SRG,
the routing of calls to the local gateway is important (especially when toll
charges apply to calls made from the central Call Server that controls the
telephone). The administrator can configure digit manipulation through zone
attributes for IP Phones to select a main office or branch office that provides
PSTN access local to the destination of the call.
Calls from the PSTN to users within the network can be routed with the
various ESN numbering plan configurations.
To access local PSTN resources, outgoing calls can be routed using ESN as
well as zone parameters that enable digit insertion. The zone parameters force
calls made by an SRG user to be routed to the desired local PSTN facilities.
Note: Outgoing calls can include local and, optionally, long distance
calls.
Nortel recommends that the Branch User ID (BUID) be the same at the
branch office as the DN at the main office. A BUID has a maximum of 15
digits. Under the recommended Coordinated Dialing Plan (CDP), the BUID
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