CM9015 Product Descriptions

5/25/2018 CM9015 Product Descriptions

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Telrad Networks Tel : +972 (3) 915 7300Telrad Park Afek Fax: +972 (3) 915 7305P.O. Box 48814, Hamelacha St.48091 Rosh Haayin

ISRAEL

Duet 9015

Product Description

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Telrad Restricted

The information contained in this document is the property of Telrad

and should be considered restricted. The holder of this document shall

keep all information contained herein confidential and shall protect

same in whole or in part from disclosure and dissemination to all third

parties.

Telrad 2006


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2 of 54 Duet 9015 Product Description


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Duet 9015 Product Description 3 of 54

Table of Contents

Preface ....................................................................................................................................... 7Chapter 1

I ntroducti on .......................................................................................................... 9

Chapter 2 System Description.............................................................................................. 12

2.1 The Duet 9015 as an IP Network Element .............................................................. 122.1.1 IP Interfaces and Addresses ......................................................................................... 122.1.2 IP Address Resolution.................................................................................................. 122.1.3 Synchronization on Network Time .............................................................................. 132.1.4 Remote management .................................................................................................... 13

2.2 The Duet 9015 in the VoIP Network ....................................................................... 132.3 The Duet 9015 in the PSTN Network ...................................................................... 13

Chapter 3 Product Description ............................................................................................ 153.1 Functional Representation ....................................................................................... 153.2 The Resource Management Function ..................................................................... 153.3 The Signaling Gateway Function ............................................................................ 15

3.3.1 SS7 Signaling Gateway................................................................................................ 153.3.2 PRI Signaling Gateway ................................................................................................ 173.3.3 MF/CAS Signaling Gateway ....................................................................................... 18

3.4 The Media Gateway Function ................................................................................. 193.4.1 H.248 version and coding ............................................................................................ 193.4.2 Profile ........................................................................................................................... 203.4.3 Transport ...................................................................................................................... 203.4.4 H.248 Media Gateway ................................................................................................. 20

3.5 The Media Transcoding Function ........................................................................... 263.5.1 Media Transport ........................................................................................................... 263.5.2 Media Format ............................................................................................................... 263.5.3 Additional Media Services ........................................................................................... 27

3.6 Operation, Administration and Maintenance ........................................................ 313.6.1 User Perspective........................................................................................................... 313.6.2 Human-Machine Interface (HMI) ................................................................................ 313.6.3 Alarm Generation and SNMP Traps ............................................................................ 343.6.4 Software loading/Upgrade ........................................................................................... 34

3.7 System Architecture ................................................................................................. 363.7.1 The Shelves .................................................................................................................. 363.7.2 The System Alarm Card............................................................................................... 373.7.3 The Processing Cards ................................................................................................... 373.7.4 The Duet 9015 System ................................................................................................. 393.7.5 The Switch/Router ....................................................................................................... 393.7.6 Reliability, Availability and Redundancy .................................................................... 403.7.7 Power Supply Redundancy .......................................................................................... 41Chapter 4 Technical Specif ications ..................................................................................... 42

4.1 Capacity and Configuration .................................................................................... 42


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4.1.1 Large configurationDuet 9015L .............................................................................. 424.1.2 Small configuration...................................................................................................... 42

4.2 Supported Codecs and Periodicity .......................................................................... 434.3 Interfacing ................................................................................................................. 43

4.3.1 The GCC Pack Interfaces............................................................................................. 434.3.2 The GMC Pack Interfaces ............................................................................................ 444.3.3 The System Alarm Card Interfaces .............................................................................. 45

4.4 Power Requirements ................................................................................................. 454.5 Thermal Profile ......................................................................................................... 454.6 Product Integrity Specifications .............................................................................. 45

4.6.1 Environnemental .......................................................................................................... 454.6.2 EMC ............................................................................................................................. 464.6.3 SAFETY ...................................................................................................................... 464.6.4 TELECOM ................................................................................................................... 46

4.7 Mechanical Specifications ........................................................................................ 464.7.1 Stationary vibration (In-use) ........................................................................................ 464.7.2 Earthquake ................................................................................................................... 474.7.3 Transportation Vibration :............................................................................................ 474.7.4 Handling Drop Tests .................................................................................................... 474.7.5 Physical Dimensions .................................................................................................... 47Chapter 5 Glossary ............................................................................................................... 49Chapter 6 Bibliography ........................................................................................................ 52


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Table of Figures

Figure 1: The Duet 9015............................................................................................................ 9Figure 2: The Duet 9015 in the IP and TDM networksSS7 Backhauling ............................ 17Figure 8: The Duet 9015 in the IP and TDM networks

PRI Backhauling ........................... 18Figure 10: The TOS field format as per RFC 791 ................................................................... 30

Figure 11: The TOS field format as per DiffServ (RFC 2474) ................................................ 30Figure 12: Duet Element Manager Screen Shot ...................................................................... 32Figure 13: Duet EMS System ................................................................................................... 33Figure 14: The 8U shelf ........................................................................................................... 36Figure 15: The 4U shelf ........................................................................................................... 37Figure 16: The Duet 9015 System ........................................................................................... 39Table of Tables

Table 1: H.248 Packages for MF/R1 ....................................................................................... 19Table 2: H.248 Packages for MFC/R2 .................................................................................... 19Table 3: Duet Faults to "netfail" causes .................................................................................. 23Table 4: FAX/Textphone/Modem Tones Detection Package support ...................................... 24Table 5: Duet Faults to ServiceChange Reasons .................................................................... 25Table 6: Codecs supported by the Duet 9015 .......................................................................... 26Table 7: Silence Suppression and Comfort Noise Generation Methods.................................. 27Table 8: Packet loss compensation methods ........................................................................... 28Table 24: Codecs supported by the Duet ................................................................................. 43Table 25: The GCC pack interfaces......................................................................................... 43Table 26: The GMC pack interfaces ........................................................................................ 44Table 27: The System Alarm Card interfaces .......................................................................... 45 Table 13: Temperature and Humidity Specifications ........................................................ 45Table 29: Drop Test Criteria ................................................................................................... 47


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Preface

This document presents the architecture, functions and interfaces of the Duet 9015.

This Product Description is organized into the following sections:

Introduction - A brief description of the Duet 9015.

System Description - Describes the context in which the Duet 9015functions.

Product Description - Describes the various functions of the Duet 9015 suchas:

System Architecture - Describes the overall product architecture.

OAM - Presents the Operational, Administration and Maintenance

aspects of the Duet 9015. Data Path - Describes data flow and the protocols used in the system.

H/W Description - Details the Duet 9015H/W.

Technical Specifications - Gives the numerical values for the varioustechnical requirements.

Engineering and Installation - Presents the factors needed to ensure properDuet 9015functioning.

References - Lists all documents referenced in this Product Description.

Readers should be familiar with packet data networks and the voice over packetnetworks technology.


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Chapter 1 Introduction

The Duet 9015 is a small/medium H.248-controlled Trunk/Media Gateway designed

to provide connectivity between the PSTN and a VoIP network. The Duet is fullycontrolled by the VoIP network's Softswitch which instructs it to set-up and tear-

down the media connections to other endpoints in the VoIP network (i.e. media

control) as well as to detect events and generate signals on the links connecting it to

the PSTN.

The Duet 9015 supports the following functionalities:

SS7 Trunk Gateway (i.e. SS7 Signaling Gateway (SG) and H.248 controlledMedia Gateway(MG))

PRI Trunk Gateway (i.e. PRI SG and H.248 controlled MG)

E1/T1 MF/CAS Trunk Gateway (i.e. MF/CAS SG and H.248 controlled MG)

Figure 1: The Duet 9015

The combination of the Duet 9015 and a SoftSwitch functions as an exchange of SS7,

PRI and MF/CAS Trunks. The SoftSwitch provides the call processing, billing andadministrative functions and the Duet provides the signaling translation and media

conversion.

The Duet 9015 provides the following main functions:

Signaling Translation

For SS7 signaling, the Duet serves as a signaling gateway (SG) for SS7

backhaul and tunneling (i.e. peer-to-peer). In the SS7 backhaul architecture, the

Duet transports SS7 signaling between an SS7 SEP (e.g. SSP or STP) and a

MGC/ASP. In the SS7 tunneling or peer-to-peer architecture, the Duet

transports SS7 signaling between an SS7 SEP (e.g. SSP) and another SS7 SEP(e.g. SSP or STP) via a point-to-point connection through an IP network. The

SS7 tunneling configuration requires two SGs: one SG is connected to an SS7


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SEP and the other to its peer SS7 SEP. Both architectures use an interworking

protocol called SIGTRAN. SS7 tunneling will be supported in a future phase.

For PRI signaling, the Duet serves as a signaling gateway (SG) for PRI

backhaul. In PRI backhaul, the Duet transports PRI signaling between a PRI

PBX or a PRI LE (at a future phase) and a SoftSwitch. PRI backhaul also uses

SIGTRAN as the interworking protocol.

For E1/T1 MF/CAS, the Duet converts the E1/T1 MF/CAS signaling into H.248

signaling and vice versa.

Media Conversionallows converting media formats such as: PCM to G.711,G.729 or G.723.1. The media conversion is bi-directional. The Duet 9015 also

provides additional media related services such as: Voice Activity Detection

(VAD), Silence Suppression, Comfort Noise Generation, Echo Cancellation

and more (for more details please refer to section3.5 on page26).

Media ControlThe Duet is an H.248-controlled MG: the make and break of

the media connections through the IP network is performed using the H.248protocol.

A Domain Name Server(DNS) client, integrated into the Duet 9015, enablesthe Duet 9015 to communicate with the networks DNS servers for IP address

resolution needs.

An NTP client, integrated into the Duet 9015, enables the Duet 9015 to besynchronized with the network's NTP servers.

The Duet implements and complies with the following standards:

ITU-T Q.700Q.703 (SS7).

SS7 MTP2 : ETSI 300 008 and 300 008-1

SS7 MTP2 : ANSI T1.111

ITU-T Q.921 (LAPD).

ETSI 300 011, 300 125 (LAPD)

ITU-T Q.310, Q.314, Q.316, Q.316, Q.317 for MF/R1 line signaling andgeneral information, and ITU-T Q.320, Q.322, Q.323, and Q.325 for register

signaling.

RFC 2719 (SIGTRAN).

RFC 2960 (Stream Control Transmission Protocol - SCTP) and IETF draft"sctpsocket".

RFC 3331 (MTP Layer 2 User Adaptation - M2UA).

RFC 3057 (ISDN Q.921 User Adaptation Layer Protocol - IUA).

H.248 [1] and additional annexes.

The Duet 9015 is provided in two different shelf configurations: A Large shelf (8U)and a Small shelf (4U).

The Duet 9015 platform holds various dedicated hardware packs. The Duet 9015 isvery flexible: by varying the number of packs in the shelf, the capacity of the Duet

9015 can be adapted to meet the customer's needs. All packs redundancy and


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automatic switchover to a redundant pack makes the Duet 9015 a highly reliable

platform.


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Chapter 2 System Description

The Duet 9015 links a Softswitch using the SS7/SIGTRAN, PRI/SIGTRAN and

H.248 protocols on the IP network domain and SS7, PRI and E1/T1 MF/CAS trunkson the PSTN domain. The Duet links the interfaces/protocols and provides a smooth

connectivity between the PSTN domain and the IP Network domain.

2.1 The Duet 9015 as an IP Network Element

2.1.1 IP Interfaces and Addresses

A Duet system is composed of several hardware packs, some handling the media

(called GMCs) and others the signaling (called GCCs). The Duet system is

connected to the IP network via its GCC packs using a single Ethernet port(electrical 100/1000 Base-T or optical: Base-SX MMor Base-LX SM GigE). This

port is called the traffi c port. The GMC packs are connected to the IP network via

the GCCs.

The Duet is able to be connected to the back-office LAN of the operator via the out-

of-band management port of its GCCs and managed through this port. Optionally

the Duet is able to be managed inband via the traffic port. The Duet has a single IP

address for management.

The Duet provides the following IP addressing options:

1. A single IP address for the signaling and media traffic on the same physicalport (traffic port) and a management IP address on a separate out-of-band

management port.

2. Different IPs for the signaling, media and management traffic. All the threeIP's on the same physical port (traffic port).

3. Signaling and media traffic with two different IP addresses on the samephysical port (traffic port) and a management IP address on a separate out-

of-band management port.

The above IP addresses of the Duet should be defined statically (i.e. are not

dynamically assigned via DHCP).

VLAN's are supported on all options.

2.1.2 IP Address Resolution

Network elements are usually identified by their FQDN and not by their network

address (which may be dynamically assigned and changed). The Duet refers to DNS

in order to resolve the IP address of a network element (e.g. the softswitch).

The Duet 9015 integrates a DNS client element, which communicates with the DNS

servers and obtain the required FQDN to IP address mapping.


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2.1.3 Synchronization on Network Time

As part of its normal activity, the Duet generates alarms, logs, etc. As to be usable,

many of those records contain a timing indication. The Duet system handles an

internal clock, which can be configured by the administrator and is used to generate

the required timing information. In addition, as an IP network element, the Duet

integrates an NTP client, which permit the automatic synchronization of the internal

network on a common network-timing source.

2.1.4 Remote management

As an IP network element, the Duet provides the relevant Management Information

Bases (MIBs) and it is possible to control it via SNMP. Other remote control

protocol such as TELNET, SSHv2, FTP and sFTP are also implemented. Please

refer to section 3.6.2 "Human-Machine Interface (HMI)" on page 31 for more

information.

A Duet Element Manager System (EMS) are available through which the networkmanager can perform OAM&P functions on the Duet.

2.2 The Duet 9015 in the VoIP Network

The Duet 9015 uses the H.248 and SIGTRAN protocols to provide telephony services

using the VoIP technology. The Duet is fully compliant with the H.248 [1] and

SIGTRAN (M2UA and IUA) standards. By implementing these specifications, the

Duet becomes a certified mean to provide telephony and advanced services over a

converged network (H.248 and SIGTRAN in the IP domain; SS7, PRI and MF/CAS

in the PSTN domain).

The H.248 is designed for controlling VoIP gateways by an external call control

element. This protocol assumes a call control architecture where the call control

intelligence is outside the gateway and handled by external call control element.

In this model, the Duet 9015 is a combination of two elements: H.248 MG and SS7,

PRI and MF/CAS SG. The Duet 9015 contains in the same network element an SS7

PRI and MF/CAS SG and an H.248 MG which sets-up, tears-down and manages

calls; and performs the bridging between the VoIP network and the PSTN.

2.3 The Duet 9015 in the PSTN Network

The Duet connects to the TDM switches using E1/T1 links.

The Duet synchronizes its internal clock signal generator using two methods:

The timing signal of the E1/T1 links.Each one of the connected E1/T1 links is considered as a possible timing

source. For increased availability, the Duet is capable to select any of the

E1/T1s as the timing source and if required (e.g. failure of the used E1/T1,

etc.), to dynamically and in a hitless way switch to another one.

BITS

The internal clock of the Duet is stratum 3 with holdover.


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The Duet connects to the PRI or MF/CAS PBXes via its PRI (at a future phase) andMF/CAS E1/T1 links as a Local Exchange (LE) and provides the LE clock (stratum 3

with holdover) to the PBXes via its E1/T1s.

A Duet 9015 shelf is connected to the TDM switch by up to 128 E1/T1 links in the

configuration of large shelf (8U) and by up to 80 E1/T1 links in the configuration ofsmall shelf (4U).

The assignment of the protocol (SS7, PRI or MF/CAS) is done per E1/T1 basis on the

provisioning of the system.

E1/T1 Interfaces are 120 ohm balanced for E1 and 100 ohm for T1. The 75 ohm E1

interfaces is provided via another paddleboard using miniature coax connectors (of

type Dual Port 1.0/2.3) and may require a special tool for extraction of the BNC

connector.


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Chapter 3 Product Description

3.1 Functional Representation

Using a Duet 9015, the SoftSwitch becomes an SS7, PRI and MF/CAS Trunks

Exchange providing all the telephony services to subscribers of both the IP network

and the PRI and MF/CAS PABXes in a converged network. In order to perform this

functionality, the Duet 9015 contains the following functional components in the

same network element:

SS7 backhaul SG

SS7 tunneling SG (future phase)

PRI backhaul SG

MF/CAS SG H.248-controlled Media Gateway

DNS client

NTP client

Functionally, the Duet 9015 can be divided into the following blocks:

Resource Management Function

Signaling Gateway Function

NTP Client Function

DNS Client Function

Media Transcoding Function

E1/T1 Maintenance

3.2 The Resource Management Function

The Duet 9015 uses a pool of DSPs distributed over several hardware cards that is

used to handle the media format conversion between the PSTN and the VoIP

network, as well as for the detection and generation of events. The role of theresource management function is to efficiently handle those DSP to provide to each

connection the resources it needs.

3.3 The Signaling Gateway Function

3.3.1 SS7 Signaling Gateway

The Duet supports the following architectures:

SS7 Backhauling SS7 Tunneling (Peer-to-Peer)


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3.3.1.1. SS7 Backhaul

The Duet 9015 serves as a signaling gateway (SG) for SS7 backhaul. In SS7

backhaul, the Duet serves as a SG to transport SS7 signaling between a SS7

STP/SSP and a softswitch. SS7 backhaul is defined as the termination at the SG of

the lower layers of the SS7 signaling stack for a circuit switched network and thetransport (or backhaul) of the higher layers of the same signaling stack to a

softswitch. The SS7 signaling flow through the SS7 backhaul is for call control and

not for connection/media control.

The Duet has two links to transport SS7 signaling as follows:

A signaling datalink between the Duet and the SS7 STP/SSP

A backhaul link between the Duet and the softswitch

SS7 backhaul uses an interworking protocol called SIGTRAN.

The SS7 signaling (e.g. ISUP and TCAP) transported between the Duet and the SS7STP/SSP is encapsulated in the SS7 lower layers over the signaling datalinks. The

Duet terminates the SS7 lower layer messages from the SS7 STP/SSP. The

SIGTRAN protocol is used to transport SS7 signaling messages (MTP3 and upper

layers e.g. ISUP and TCAP) between the Duet and the softswitch over the backhaul

links.

SS7 backhaul enables the Duet to act as an integrated services unit handling bothcall control and connection/media control messages. The integrated services unit is

divided into two logical parts as follows:

The signaling gateway (SG) part

The media gateway (MG) part

The SG part uses SIGTRAN/IP to backhaul call control messages between the SS7

STP/SSP and the softswitch.

The MG part uses H.248/UDP/IP to transport connection/media control messages

between the softswitch and the Duet.

For the transport of SS7 signaling over an IP network, SIGTRAN proposes two

standard protocols: M2UA and M3UA. The Duet implements M2UA. The

implementation of M3UA is left to a future phase.

M2UA Protocol Stack (SS7 user part/MTP3/M2UA/SCTP/IP)

The Duet supports the M2UA protocol stack. The M2UA is an IETF protocol

defined in RFC 3331.

M2UA is designed to support SS7 signaling over an IP network. Specifically, it

allows SS7 MTP Message Signal Units (MSUs) to be conveyed between packet

network nodes that have separate SS7 point codes. In SS7 terms, conveying MSUs

between nodes with different SS7 point codes is known as message routing.

M2UA is used to convey SS7 MSUs across the backbone packet network between

nodes with different SS7 point codes. A SS7 MSU is encapsulated in an M2UA


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packet to be routed. On receipt, the M2UA packet is unwrapped and the MSU is

processed appropriately.

The Duet supports SS7 backhauling of A-links (i.e. links that includes only SS7

signaling without media) as well as F-links (i.e. links that includes SS7 signaling

and media).

The following figure depicts the M2UA backhauling architecture which is

implemented by the Duet.

Figure 2: The Duet 9015 in the IP and TDM networksSS7 Backhauling

3.3.1.2. The H.248 Protocol

The Duet implements the H.248 protocol as defined in [1].

Following is the package that is supported by the Duet for ISUP trunks:

Package Name Functionality Reference

ct - Basic

Continuity

This package defines events and signals for continuity

test (COT). The continuity test includes provision of

either a loop back or transceiver functionality

H.248.1, Annex E.10

3.3.2 PRI Signaling Gateway

The Duet serves as a signaling gateway (SG) for PRI backhaul. In PRI backhaul, the

Duet serves as a SG to transport PRI signaling between a PRI-controlled device

(e.g. a PRI PBX) and a softswitch. PRI backhaul is defined as the termination at the

SG of the lower layers of the signaling stack for a switched circuit network and the

transport (or backhaul) to the softswitch of the higher layers of the same signaling

stack. The PRI D-channel signaling of PRI backhaul through the Duet is for call

control and not for connection/media control.

The Duet has two links to transport PRI D-channel signaling as follows:

a signaling datalink between the Duet and a PRI-controlled device


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a backhaul link between the Duet and the softswitch

PRI backhaul uses the IUA/SCTP as an interworking protocol. The IUA is an IETFprotocol defined in RFC 3057. PRI D-channel signaling is transported between the

Duet and the PRI-controlled trunks using the Q.931 encapsulated in LAPD, ITU-T

Q.921 and ETSI 300 011 and 300 125, over the signaling datalinks. The Duetterminates the LAPD messages from the PRI-controlled trunks. The IUA/SCTP

protocol is used to transport the Q.931 signaling messages between the Duet and the

softswitch over the backhaul links.

The Duet is able to be configured to be the network end or the user end of the PRI

trunk. The default configuration is for the Duet to be the network end.

The following figure depicts the PRI backhaul architecture which is implemented

by the Duet.

Figure 3: The Duet 9015 in the IP and TDM networksPRI Backhauling

3.3.3 MF/CAS Signaling Gateway

The product implements the E1/T1 MF/CAS trunks far-end interface. It translatesthe E1/T1 CAS signaling into the H.248 messages (and vice-versa) in order to setup

calls to and from E1/T1 MF/CAS Trunks exchanges (as a user/PBX side) and

PBXes (as a network/LE side).

3.3.3.1. The E1/T1 MF/CAS Protocol

R1 Line Signaling

Although E1/T1 CAS framing supports 4 signaling bits, only 1 of them (per

direction) are used for R1 line signaling. Thus, the signaling channels supporting the

R1 line signaling protocol are referred to as Afin the forward direction and Ab in

the backward direction. The forward channel indicates the condition of the outgoingcircuit and reflects the condition of the calling partys line. The backward channel

indicates the condition of the called partys line.


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R1 line signaling is defined by the ITU-T Q.310, Q.314, Q.316, Q.316 and Q.317

standards.

MF Register Signaling

The protocol consists in the exchange of multi-frequency tones. The tones used are

composed of two single-frequencies each. There are 6 possible single tones (or 15codes) in each direction. The protocol is defined by the ITU-T Q.320, Q.322, Q.323,

and Q.325 standards.

3.3.3.2. The H.248 Protocol

The Duet implements the H.248 protocol as defined in [1].

Following are the packages that are support by the Duet for MF/CAS Links:

MF/R1:

Table 1: H.248 Packages for MF/R1

Package Name Functionality Referencebcas - Basic CAS Package This package provides basic event and signal handling

for terminations that support CAS Signaling.H.248.25

MFC/R2:

The product supports ITU R2 trunks. Overlap is required. The preferred method is

using the ICASCO package from H.248.29 Annex A.

Table 2: H.248 Packages for MFC/R2

Package Name Functionality Reference

bcas - Basic CAS Package This package provides basic event and signal handling

for terminations that support CAS Signaling.

H.248.25

casblk - CAS BlockingPackage

This package provides the capability of exchangingmaintenance state between the MGC and the MG for

terminations realizing any CAS protocol.

H.248.28

icas - International CAS

Package

This package provides event and signal handling for

terminations that support International CAS signalling

H.248.28

icasc - International CAS

Compelled Package

This package defines H.248 methods to support

Channel Associated Signaling (CAS) compelled

standard en-bloc register signaling.

H.248.29

3.4 The Media Gateway Function

The MG part uses H.248/UDP/IP to transport connection/media control messagesbetween the softswitch and the Duet. The Duet implements the relevant parts of the

H.248 protocol as defined in [1]. This section contains all the H.248 protocol and

behavior requirements for the Duet device.

3.4.1 H.248 version and coding

H.248 version 1 as defined by H.248.1 [1] is used with text based (i.e. ASCII)

encoding. The H.248 protocol version 1 is included by the Duet in the

ServiceChangeVersion parameter to facilitate future upgrades to higher protocol

versions of H.248. In addition the Duet includes the H.248 protocol version in the

H.248 message header.


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3.4.2 Profile

The H.248 profile specified by this Product Description is named as Duet 9015version 1. The profile and its version number are included by the Duet in the

ServiceChangeProfile parameter with the format Duet 9015/1.

3.4.3 Transport

H.248 messages is transported using UDP and optionally via TCP on a future

release.

3.4.4 H.248 Media Gateway

The Duet SS7, PRI and MF/CAS trunks are represented at the Duet and the Call

Agent as H.248 terminations (i.e. as trunk terminations of a H.248 Media Gateway).

The Duet is represented as a single MG towards the softswitch and all its trunks are

represented as terminations of that single MG (up to 3,968 terminations).

The Duet name used in registration and in the header of commands is a fully

qualified domain name (FQDN) recognized by the DNS or an IP 4 version address.

3.4.4.1. Trunk Terminations

SS7, PRI and MF/CAS trunk/channel terminations is uniquely identified. The

naming scheme/structure is configurable in the Duet and the Call Agent, as it is

network operator dependent. The text below gives some informative guidelines for

such a naming scheme/structure.

For example the naming convention for a PRI trunk termination could be of the

form e1/link_number/timeslot_number or t1/link_number/timeslot_number, where

the prefix e1/ or t1/ is a fixed value, link_number & timeslot_number

represent non-zero integer values identifying the link number and timeslot of a

trunk. A trunk on an E1 link 1 timeslot 31 would be referred to by the name e1/1/31

and a trunk on a T1 link 1 timeslot 24 would be referred to by the name t1/1/24.

The Termination Id or name follows the H.248 [1]rules (e.g. must not exceed 64

chars) for TerminationId. However, the Duet expects the following rule in the case

of using an FQDN style:

The "user name" must not exceed 16 chars.

The "domain name" (or the pathDomainName in H.248 [1]) must not exceed47 chars (one additional char is reserved to the "@").

3.4.4.2. RTP Terminations

RTP terminations are ephemeral terminations and are created by an ADD command

and destroyed by a SUBTRACT command. They only exist for the duration of their

use and the Duet may use any naming convention to uniquely identify the RTP

terminations. The RTP and RTCP udp port range is: 400012,000.

3.4.4.3. Context

The Duet supports no more than two terminations in a context.


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3.4.4.4. Error Codes

The Duet supports an Error Descriptor with the error codes and procedures defined

in ITU-T Recommendation H.248.8 [2].

3.4.4.5. Service Change

The MGC may use ServiceChange to instruct the Duet to take a trunk termination orgroup of trunk terminations in or out of service. A ServiceChange command with

the Method parameter = Forced will cause immediate blocking of the trunk

termination, regardless of call state.

Outgoing and incoming calls are disallowed, whilst a trunk termination is out of

service. This is achieved by the Duet sending the blocked signal on the

corresponding MF/R1 trunk and the insert of the idle-pattern on the corresponding

PRI and SS7 trunk/timeslot.

The MGC may also request the unblocking of trunk terminations that have been

previously blocked at a Duet MG, by sending an H.248 ServiceChange command

specifying the trunk termination to be unblocked, and the Method Restart.

Outgoing and incoming calls are allowed from a trunk termination that has been

successfully unblocked.

The Duet MG may request the blocking of a trunk termination by sending a H.248

ServiceChange command specifying the trunk termination to be affected, using the

Method Forced. The receipt of this command causes the MGC to immediately

block the trunk termination and prevent outgoing and incoming calls from and to

the blocked trunk termination.

The Duet may also request the unblocking of a trunk termination that has beenpreviously blocked, by sending an H.248 ServiceChange command specifying the

trunk termination to be unblocked, and the Method Restart. The receipt of this

command causes the MGC to immediately allow outgoing and incoming calls from

and to the unblocked trunk termination.

Either the Duet or the MGC can unblock a previously blocked trunk termination, no

matter which side previously blocked the trunk termination.

The Duet may also request block of an entire E1/T1 by sending ServiceChange with

the reason "Termination taken out of service" (905) for all terminations of the given

E1/T1. To unblock an entire E1/T1 the Duet sends ServiceChange with the reason"Service Restored" (900) for all terminations of the given E1.

The status of a termination (blocked/unblocked) is not preserved over restart of the

GCC.

3.4.4.6. Time Stamps

The Duet includes a time stamp in every ServiceChange and NOTIFY commands .

The reference of the time stamp is the Duet internal clock or obtained from an NTP

server.


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3.4.4.7. Digit Map Descriptor

For MF/CAS trunks, the Duet supports downloadable digit maps from the MGC

using H.248. The digit maps may be downloaded during start up (defined on the

root Termination) and may apply to the entire Duet or individual analogue

terminations. Alternatively, the digit map may be dynamically specified by theMGC during call establishment on a specific trunk termination. In this case the digit

map would apply only to this specific trunk termination and only during this call.

The Duet is able to store up to 16 DigitMaps (including the configurable one global

public dial plan). Each DigitMap may include up to 16 patterns.

The DigitMap names are 1 to 32 alphanumeric.

The length of the digit map is limited to 400 characters and up to 24 dialed digits.

3.4.4.8. Loss of communications with the Duet

When UDP is used as the transport protocol, then the softswitch typically uses the

AuditValue command against the ROOT termination with an empty Audit

Descriptor as a keep-alive message for detecting loss of communications with the

Duet in the absence of other H.248 messages. If no reply is received to the

AuditValue message, the softswitch determines that it has los t communication

with the Duet. It should be noted that this keep-alive mechanism also complements

the H.248.14 [3]Inactivity Timer package used by the Duet for detecting loss of

communications with the MGC. Loss of communication with the Call Agent is

described in section3.4.4.9 on page22.

3.4.4.9. Redundancy and Resilience

The Duet has 99.999% availability in order to achieve the same service level

agreements as offered on current PSTN networks.

The ITU-T Recommendation H.248.14 (03/2002) Gateway control protocol:Inactivity timer package [3], provides a package that allows an MG to detect the

failure of its active MGC through message inactivity. This package is mandatory

for UDP transport and is used by the Duet for detecting loss of communications

with the Call Agent.

This package contains an event that can be implemented by a MGC and by a MG

on its root termination. The purpose of the event is to allow the MG to detectperiods of silence of messaging from the MGC. Once the period of silence exceeds

the threshold provided in the event the MGC is notified.

Under fault conditions and in a future phase the Duet will be capable of re-

registering with a secondary MGC:

The Duet supports a secondary MGC.

The change over mechanism for trunk terminations is as defined by H.248.1[1]clause 11.5.

The Duet supports revertive switch over back to the repaired MGC. Thismode of operation is triggered by the current working MGC by using the

Hand off procedures described in H.248.1 clause 11.5.


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Under change over the Duet and the MGC preserve those calls that are in astable and established state.

3.4.4.10. Supported H.248 Packages

H.248 Terminations

The H.248 SoftSwitch expects the Duet MG to support the following packages:

1. Generic (g)

2. Base Root (root)

3. FAX/Textphone/Modem Tones Detection (ftmd) [H.248 Annex F] [4]

4. DTMF Detection (dd)

5. Call Progress Tone Generator (cg)

6. Basic Call Progress Tones Generator with directionality (bcg)

7. Expanded Call Progress Tones Generator (xcg)

8. Basic Services Tones Generator (srvtn)

9. Network (nt)

10.RTP (rtp)

11.TDM Circuit (tdmc)

12.Basic DTMF Generator

13.Inactivity Timer (it) [H.248.14][3]

Generic (g)

The values of the causeevent which are supported by the Duet are:

"NR"Normal Release

"UR"Unavailable Resources

"FP"failure, Permanent (redundant or second GMC failure, E1/T1failure)

"UN"Unsupported

Network (nt)

This package defines properties of network terminations. The qualertevent (qualityalert) is not supported.

netfail event: The Duet may detect various faults (e.g. 2nd GMC failure) whichaffects some of its terminations and requires clearing up the calls associated with

these terminations. The MGC is responsible for cleaning up these calls.

Table 3 specifies the faults and their mapping to corresponding "netfail" causes.

Table 3: Duet Faults to "netfail" causes


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Duet Fault Fault Description "netfail" Cause

GMC Failurea all calls associated with this GMC should be

cleared up

"GMC failure"

RTP Broken the associated call should be cleared up "Packet-side bearer failure"

E1/T1 Failure all calls associated with this E1/T1 should becleared up

"E1/T1 failure"

This method is used only if the MGC is interested to receive the "netfail" event andrequested the Duet to detect and notify. If the MGC doesnt request this event the

ServiceChange command with appropriate reasons is used (please refer to section

3.4.4.11 on page25).

FAX/Textphone/Modem Tones Detection (ftmd) [H.248 Annex F] [4]

This package defines an event to detect the presence of data traffic (fax, textphone

or modem) on a line. This Package extends the possible values of tone id in the

"start tone detected" event of the Tone Detection (tonedet) package. Only the tone

ids of Fax/Modem are supported.

Since the main intention of this event is used to effect the compression options and

echo cancellation on the line (so that an audio codec capable of transmitting modem

signals can be invoked to handle the connection when needed), the notification of

the specific fax/modem tone type is not vital. Thus, in cases where the Duet is not

capable with the specific fax/modem tone detection, the tone-id "CNG" is notified

as the default fax/modem tone id.

The Duet may work also in an autonomously mode (i.e. without notifying the MGC

and waiting for its further call control). In this mode, the near end echo canceller is

autonomously disabled upon detection of a fax/modem call as defined in G.168 and

codec is changed to G.711. The selection of G.711 A-law or -law is selected based

on the priorities in the SDP codec negotiation. The FAX/Modem mode is

configurable per system.

Table 4: FAX/Textphone/Modem Tones Detection Package support

Symbol Definition Support

CNG a T.30 fax calling Yes

V21flag a V21 tone and flags Yes

CIV18 a V.8 CI with V.18 call function No

XCI a V.18 XCI No

V18txp a V.18 "txp" No

Belltone a Bell 103 carrier, either the high or the lowfrequency channel (as defined in ITU-T Rec. V.18)

No

Baudot a Baudot initial tone and character (as def. in ITU-TRec. V.18)

No

Edt an EDT initial tone and character (as def. in ITU-TRec. V.18)

No

aEither in a non-redundant configuration or in a failure of more than one GMC


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Symbol Definition Support

Ctm a CTM signal was detected (as def in 3GPP TS

26.226)

No

CIdata a V.8 CI with any data call function Yes

CT a V.25 calling tone YesCIfax a V.8 CI with facsimile call function Yes

V21tone a V.21 carrier, either high or low frequency channel Yes

V23tone a V.23 carrier, either high or low frequency channel Yes

V8bis a V.8bismodem handshaking signal Yes

ANS V.25 ANS, equivalent to T.30 CED from answeringterminal

Yes

ANSAM V.8 ANSam Yes

3.4.4.11. ServiceChange for Faults Notification

If the MGC doesnt request the detection of the "nt/netfail" event, it won't getinformed of the Duet faults (reported by the "nt/netfail" event) and therefore

associated calls won't be cleared.

The ServiceChange Command allows an MG to notify the MGC that a Termination,

or group of Terminations, is taken out of service using the Method parameter (set to

"forced") with an appropriated reason parameter, which specifies the reason why the

ServiceChange has occur. The MGC is responsible for cleaning up the Context with

which the failed Termination is associated. Table 5 specifies the faults and their

mapping to ServiceChange commands and corresponding reasons.

The meaning and interpretation of the ServiceChange reasons are according to

H.248.8 [2].

Table 5: Duet Faults to ServiceChange Reasons

Duet Fault Fault Description ServiceChange Commands

GMC Failurea all calls associated with this GMC

should be cleared up

ServiceChange with the reason "Transmission Failure"

(907) followed by a ServiceChange (method = forced)

with the reason "Service Restored" (900) for each

termination that is associated with the failed GMCRTP Broken the associated call should be

cleared up

E1/T1 Failure all calls associated with this

E1/T1 should be cleared up

ServiceChange with the reason "Loss of lower layer

connectivity" (906) followed by a ServiceChange

(method = forced) with the reason "Service Restored"

(900) for each termination that is associated with the

failed E1.

3.4.4.12. AuditValue

The AuditValue command returns the current state of properties, events, signals andstatistics of Terminations. The Duet supports this command and sends the requested

information, except for the parameters of the SDP.

aEither in a non-redundant configuration or in a failure of more than one GMC


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3.5 The Media Transcoding Function

The Duet 9015 provides TDM and VoIP to/from VoIP gateway functions.

3.5.1 Media Transport

3.5.1.1. Voice

On the PSTN side, the Duet 9015 is connected to the PSTN via TDM links (e.g.

E1/T1 links).

On the VoIP network side, the media is transported using the Real-time Transport

Protocol (RTP). The RTP protocol and associated RTP Control Protocol (used to

monitor the line) are defined by the IETF RFC 3550 [5]. The relevant parts of the

RTP profile for Audio and Video (IETF RFC 3551 [6]) are also implemented.

The product supports end of call QoS reporting using H.248.

3.5.1.2. Fax and Modem

On the PSTN side, the Fax and Modem calls are transported as voice calls.

On high quality network (very low delay, no jitter and packet loss), the Fax and

Modem calls are transported as normal voice calls using the G.711 codec. This

method is called pass through.

On low quality and not well-managed networks or networks that use only low bit

codecs (e.g. G.729 or G.723.1), the Fax over IP (FoIP) ITU-T T.38 [7] protocol is

used for Fax transport. T.38 can also be used with G.711.

Also, the Duet 9015 is capable of recognizing the Fax or Modem call, freeze its

jitter buffer and use G.711 (on high quality network) on this call. The echo canceller

is removed only in the case of a detection of a slow modem.

3.5.2 Media Format

3.5.2.1. PSTN

On the links going to the PSTN side, the media is encoded in PCM format. The

compounding may be either A-Law or -Law. The administrator provisions thecompounding to be used by the Duet 9015. The Duet implements the corresponding

voice law on the media packets (RTP packets) which are transferred to the IP

network. There may be instances where A-law is required with T1 interfaces (e.g. in

CALA), as well as the standard of E1 with A-law and T1 with law.

3.5.2.2. VoIP Network

The following codecs are supported by the Duet 9015:

Table 6: Codecs supported by the Duet 9015

Codec Bandwidth 10ms 20ms 30ms 40ms 50ms 60ms

G.711 A/-Law [8] 64 Kbps

G.726 16, 24, 32, 40 Kbps

(32) (32) (32)


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Codec Bandwidth 10ms 20ms 30ms 40ms 50ms 60ms

G.729A/B/E [9] [10] 8 Kbps

G.723.1/A [11] [12] 5.3 or 6.3 Kbps

EVRC 4.8 or 9.6

AMR-NB 4.95 / 5.15 / 5.95 / 6.7 /7.4 / 7.95 / 10.2 / 12.2

The product supports Clear Channel Data according to RFC 4040 and/or x-ccd.

3.5.3 Additional Media Services

3.5.3.1. Silence Suppression and Comfort Noise Generation

In order to reduce furthermore the bandwidth consumption and optimize the

available bandwidth usage, the Duet 9015 uses a silence suppression mechanism.

For an improved voice quality, a comfort noise generator is also introduced.

The following table indicates the standard which describes the silence suppressionand comfort noise generation mechanism for each codec provided.

Table 7: Silence Suppression and Comfort Noise Generation Methods

Codec Silence Suppression Comfort Noise Generation

G.711 A/-Law As per G.711 Appendix II [13] As per G.711 Appendix II [13]

G.726 As per G.726 As per G.726

G.729A/B/E As per G.729B As per G.729BG.723.1 As per G.723.1A As per G.723.1A

3.5.3.2. Echo Canceller

To eliminate the echo that may be present e.g. on the TDM links coming from thePSTN (due to high delay) the Duet 9015 contains echo canceller.

The echo canceller is implemented as per the ITU-T recommendation G.168 [14].

The max echo delay tail is 128ms. Please refer to section Error! Reference source

not found. "Error! Reference source not found." Page Error! Bookmark not defined.

for detailed information about the pack.

3.5.3.3. Jitter Buffer

The Duet 9015 is equipped with dynamic jitter buffers enabling it to adapt to thevariations of the network condition.

Through provisioning, the administrator has the control over the maximum size of

the jitter buffer (up to 300ms), and the possibility to freeze its size (deactivate the

automatic size adaptation).


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3.5.3.4. RTP Broken

The Duet provides the detection of broken RTP flow. The time which is defined as

"RTP Flow disruption" is configurable. In case of RTP Flow disruption detection,

the Duet sends H.248 message to the Softswitch in order to drop the call. The

activation of the feature is provisionable.

3.5.3.5. Packet loss Concealment

The product supports packet loss concealment (PLC) when there is a loss of one or

more incoming voice packets. PLC algorithms may consist of replaying previous

packets, inserting comfort noise or utilize sophisticated predictive schemes.

The Duet 9015 handles packet loss compensation as per the following standards:

Table 8: Packet loss compensation methods

Codec Compensation

G.711 A/-Law As per G.711 Appendix I [15]

G.726 As per G.726

G.729A/B/E As per G.729A/B/E

G.723.1 As per G.723.1

This mechanism is permanently active and does not require any intervention form

the Softswitch or the operator.

3.5.3.6. Tone Generation and Detection

The product supports PSTN tone generation and detection for user defined callprogress tones and DTMF tones.

Call progress tones are defined by the following H.248 packages:

Basic call progress tones generator (cg) includes dial tone, (audible) ringingtone, busy tone, congestion tone, special information tone, warning tone,

payphone recognition tone, call waiting tone, and caller waiting tone

Basic call progress tones generator with directionality (bcg) Expanded call progress tones generator (xcg) includes comfort tone, off-hook

warning tone, negative acknowledge tone, vacant number tone, and special

conditions tone

Basic services tones generator (srvtn) includes recall dial tone, confirmationtone, held tone, and message waiting tone

3.5.3.7. Continuity Tone (COT) Generation and Detection

The product supports an industry standard High/High COT. High/high COT refers

to a 2010 Hz tone at either end (THRH). It is sometimes referred to as 4-wire COT.

The specification that details this is ANSI T1.113.4 Annex B2. There are additional

requirements for a 4-wire TLRH and 2-wire THRL as per Annex B3 that are likely

to emerge as well.

The product supports continuity testing on the TDM side by transmitting a tone and

looking for a tone in response. COT is provisionable, with a choice of type. Defaultis 4-wire.


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The product supports an industry standard 4-wire High/High COT as per H.248.1Annex E. Under the command of the softswitch, the DUET originates a 2010 Hz

continuous tone towards the TDM network and searches for such a tone in response.

During this period, the ECAN is disabled. The COT tone is not played toward the

packet side, comfort noise is played out instead. With H.248, the continuity timer is

contained with the DUET and that continuity tones are played until either the timerexpires, or a return tone is detected. Signal requests for simultaneous or

concatenated play out of any tone or announcement in conjunction with a continuity

test on the same endpoint results in the command being rejected. Reception of an

unexpected return signal (e.g., 1780Hz tone) in ignored and expected tone is looked

for until timer expiry or cancellation of test. The DUET transmits at 2010Hz 8Hz

and accept COT tones between 1970Hz and 2040Hz.

The product supports 2-wire COT to support interworking with the AT&T ESS

switches. If the DUET is the originating end, then it transmits 2010Hz and look for

a return frequency of 1780Hz. If the DUET is the terminating end, then it looks for

2010Hz and respond with the return frequency of 1780Hz. The DUET transmits thehigh tone at 2010Hz 8Hz and low tone 1780Hz 8Hz. Incoming COT tones are

accepted if high tone is between 1970Hz and 2040Hz and low tone 1780Hz 30Hz.

In a mixed combination of 2-wire and 4-wire COT, the DUET have the ability to actas either end:

4-wire (TLRH): The DUET originates by sending 1780Hz and looks for return

frequency of 2010Hz. In terminating mode, the Duet would look for 2010Hz and

respond by sending the return frequency of 1780Hz.

2-wire (THRL): The DUET originates by sending 2010Hz and looks for return

frequency of 1780Hz. In terminating mode, the DUET would look for 1780Hz and

respond by sending the return frequency of 2010Hz.

3.5.3.8. DTMF Handling

For the Duet 9015 to permit the usage of DTMF activated devices, some DTMF

handling has to be performed.

The Duet 9015 is able to detect incoming DTMF tones from the PSTN side and

generate DTMF tones towards the PSTN side.

DTMF tones may arrive from or send to the VoIP network side in the followingways:

In-band tone (G.711)

In-band Signaling (RFC2833 [16])

The Duet 9015 supports both types.

3.5.3.9. DiffServ Handling

The Duet 9015 handles the Differentiated Services (DiffServ) mechanism. The

administrator can predefine IP packet DiffServ bits values.

A provisioned DiffServ value can be inserted in all media (RTP and RTCP) packets.


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The DiffServ Bits are handled as follows: the IP packet header and its Type ofService (TOS) field is defined in the IETF RFC 791 [17] (the usage of the TOS

parameter was redefined in later RFCs). The IETF RFC 2474 [18] redefines the

format and the usage of the TOS parameter for the DiffServ usage.

0 1 2 3 4 5 6 7

Precedence D T R 0 0

Figure 4: The TOS field format as per RFC 791

0 1 2 3 4 5 6 7

DSCP CU

DSCP: differentiated services codepoint

CU: currently unused

Figure 5: The TOS field format as per DiffServ (RFC 2474)

The Duet 9015 supports both the TOS (a.k.a IP Precedence) and the DSCP Diffserv

methods.

When using the DiffServ function, the administrator provisions the values of eitherthe DSCP or TOS fields. This value is to be placed in the DSCP or TOS (a.k.a IP

Precedence) part of the TOS field of the relevant IP packets (signaling or media).

3.5.3.10. VLAN and L2 CoS (802.1p&q)

The product is able to support separation of management traffic, media andsignaling. Separation is either physical or logical via VLAN Tagging.

The product have an out-of-band management 10/100 BaseT Ethernet port. Thisallows the Duet to provide a physical separation of management traffic and other

traffic (media and signaling). However, the product optionally support management

from the traffic port (i.e. inband). For this option, the Duet provides a logical

separation of the management traffic and other traffic.

The Duet 9015 supports the VLAN and the L2 Class of Service (COS) features. The

Duet is able to assign a pre-configured VLAN id and a pre-configured Class of

Service value on the Ethernet frame of IP packets (signaling or media). E.g. theadministrator may configure the signaling to be in one VLAN and the media to be a

different VLAN.

Changing the mode of work of the Duet 9015 from working without VLAN to

working with VLAN or vise versa may require restart of the GCC pack.

Packets with VLAN is supported only if the Duet 9015 has been configured to workwith VLAN.

Changing the management from the management port to the traffic port and vise

versa may require restart of the GCC pack.


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3.6 Operation, Administration and Maintenance

The OA&M operations on the Duet 9015 do not impact service.

3.6.1 User Perspective

3.6.1.1. Subscriber

Accessing and using the Duet 9015 does not involve any additional dialing. The

subscriber is not aware that a Duet 9015 is involved in call completion.

3.6.1.2. Administrative Personnel

Administrative personnel access the Duet 9015 from a SNMP network manager or

from a simple Telnet interface.

Downloading and uploading the provisioning is also supported using FTP. The FTP

files are simple ASCII files with the same User Interface of the Telnet CLI.

3.6.2 Human-Machine Interface (HMI)

3.6.2.1. Management Protocol

The Duet 9015 is capable of being remotely managed using SNMPv2c [19] [20]

[21], TELNET and SSHv2 protocols. All the management protocols are terminated

and handled by the managed card.

3.6.2.2. Management Interfaces

The administrator has several means to connect and manage the Duet:

Local Craft TerminalThe administrator has the possibility to connect a monitor/local craft terminal

(using RS-232) to the Duet and then access the Duet's CLI (Command Line

Interface) to administer and manage Duet.

TelnetThe administrator has the possibility to remotely connect to the Duet using any

standard compliant Telnet client (MS HyperTerminal, PuTTY, etc.). Once the telnet

connection is established, the administrator accesses via it to the Duet CLI

interface.

Secure Shell (SSH)The administrator has the possibility to remotely connect to the Duet using any

standard compliant SSHv2 client (PuTTY, Secure CRT, etc.). Once the telnet

connection is established, the administrator accesses via it to the Duet CLI

interface.

For more information about this feature please refer to the Feature Specification

Secure Shell Protocol for the Duet 6000 Series [22].

SNMP

The administrator has the possibility to remotely manage the Duet using theSNMPv2c [23] [24] [25] protocol. For this purpose, the Duet implements a

SNMP2c agent, the relevant standard MIBs and some proprietary MIBs. It is


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possible to provide the MIBs to the clients permitting the integration of the Duet

management into an overall network management application.

Please refer to section Error! Reference source not found. "Error! Reference source

not found." on page Error! Bookmark not defined. for a list of the MIBs supported.

Element Manager (EM)

The Duet Maestro Element Manager is adapted to be able to provision, manage and

administrate the Duet 9015 systems.

The Duet Maestro specifications are described in a separate document.

Once the proper modifications are implemented, the administrator has the

possibility to use the Duets Element Manager to control, configure and manage the

Duet units found in his network. The EMS supports redundancy and redundant

Ethernet links.

Figure 6: Duet Element Manager Screen Shot

It is possible to simultaneously use up to 6 CLI interfaces, independently of the

connection mean used: Local Craft, Telnet or SSHv2 (clearly there cannot be more

then one Local Craft Terminal connected at the same time).

Duet EMS provides SNMP and/or FTP/sFTP northbound interface for seamless

integration with external OSS systems.

The Duet supports Username and Password login to Duet management interfaces

for Telnet, FTP and SSH and EMS.

3.6.2.3. Duet EMS

The Duet EMS is a client-server application suite providing comprehensive and

easy-to-use platform for controlling, managing, and monitoring one or many Duet


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Gateways. The EMS provides clear Graphical User Interface that enables

provisioning of all available services and monitoring the device and service status.

The EMS consists of:

EMS Server Communicates with all managed Duet 9015 devices using

SNMP v2/v3 to perform all configuration and management tasks and receivemanagement information.

EMS ClientCommunicates with the EMS Server to enable configurationand management data, visualize monitoring information and alarms.

Figure 7: Duet EMS System

The Duet EMS features full-redundant cluster configuration supporting a redundant

Ethernet connectivity.

The Duet EMS supports management functions in all relevant FCAPS areas as it

defined by TMN model:

Fault

Monitoring of alarms and status of all managed Gateways and their modules.

Correlation of clear notifications to previously raised alarms.

Suppress, filter and partition faults by different aspects of its product structurecard, shelf, application, etc.

Capable of storing fault data for up to 30 days.

Configuration

Showing module/card population of all managed Gateways

Easy-to-use GUI for provisioning all available services in the Gateway Software upgrade


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Automatic and periodic configuration backup

Performance

Collecting and storing all operational measurements provided by the Duet.

Graphical and tabular presentation of OM data

Security

Flexible user managementdefine set of permissions per user

SNMPv3 security features

Logged-In users tracking

Northbound Interface

Duet EMS provides SNMP northbound interface for seamless integration with

external OSS systems

For more details please refer to the Duet EMS product spec.

3.6.2.4. Configuration and Provisioning Scripts

It is possible to automatically configure and provision the Duet via scripts.

Once the system is active and the network parameters are configured (IP address,

mask, default gateway, etc.) it is possible to use the FTP [26] or the Secure FTP

(sFTP) protocolto download to the Duet a configuration and provisioning file.

3.6.3 Alarm Generation and SNMP Traps

The Duet 9015 system is designed so that management traffic is reduced to the

minimum required. Alarms are sent to the management system via the SNMP trapmechanism.

After receiving an alarm the management system investigates the status of the

component that generated the alarm and reports to the operator. Each trap sent has a

configurable alarm level (Informational, Minor, Major or Critical). The alarm

severities are user configurable. The Duet maintains an active alarm table (trouble

list).

The Duet supports up to four destinations for faults.

3.6.4 Software loading/Upgrade

The Duet supports a remote software upgrade capability via FTP. Software

upgrades is automated via the EMS.

A software upgrade or rollback is able to be completed without dropping any calls

or any denial of calls for longer than a second. This process is automated via the

product EMS in order to make this as easy and error-proof as possible. The upgrade

or rollback is able to be completed easily in a normal four-hour maintenance

window. The rollback to the previous software release is performed without loss of

configuration or provisioned data.

The Duet supports the Automatic Software Upgrade feature. There are four differentloadfiles that can be downloaded individually or together (files of GCC, GMC,

Alarm Card and DSP).


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The Duet software consists of different software loads related to several packs. Theproduct has an umbrella software version (e.g. Duet 9015 v1.0) which consists of

the following software packages: GCC, GMC, DSP and Alarm pack. Each software

load have its own version. Change in the version of one of the components cause a

change to the umbrella software version.

All software is kept on the embedded flash disk on the GCC. A configurableparameter is defined as to whether an inserted card gets its software from the shelf

or use what it already has loaded on it (in case that its software is not aligned with

the 'approved software version' of the shelf). The default is to get it from the shelf.

The GCC is upgraded using the GCC's Embedded Flash Drive. Software upgrade of

the GCC involves the download of the new load file to the GCC's Embedded Flash

Drive, flashing the software and performing a restart after switching the activity to

the mate GCC.

The Duet allows the user to perform file system operations on the files that are

saved in the Embedded Flash Drive (e.g. rename, delete, create/delete a folder, copy

to flash, etc.).

FTP is used by the GCC to connect to the other pack(s) and download the new load

file from its Embedded Flash Drive.

The software on the GMC and GCC packs is held in FLASH memory. When

booting, the load is copied from the FLASH to RAM and executed from there.

New loads is downloaded to the pack using the FTP protocol either directly from

the EMS or from the GCC's Embedded Flash Drive. It is possible to perform the

actual image download while the card is in service and without impacting on the

card's performance.

Once the new image is in memory of the pack, a reboot is used to restart the card

using the new image. If errors appear during restart procedure (after loading the new

S/W) the S/W can be downloaded again.

Software migrations of the redundant packs is able to be performed gracefully on

demand such that no calls are lost.

The Duet supports the ability to abort software release upgrades and patches with no

service impact.

An operating system upgrade on the product is done as part of a normal software

upgrade and does not have a significant impact on upgrade time.

The Duet maintains configuration and subscriber data across release upgrades,

converting existing fields as necessary, and setting defaults for new fields.


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3.7 System Architecture

3.7.1 The Shelves

The Duet 9015 is provided in a 19 cPCI 2.16 shelf in two different shelf

configurations: A Large shelf (8U) and a Small shelf (4U).

The large shelf has seventeen (17) physical pack slots for standard 6U packs and 4

slots for 3U DC power supply units, enabling power backup. Six blowers is placed

in the shelf: three above the 6U cards cage and three under the 6U cards cage,

providing the required ventilation.

The small shelf has eight (8) physical pack slots for standard 6U packs and 3 slots

for 3U DC or AC power supply units, enabling power backup. Two fan trays is

placed in the shelf: one in the front (4 fans) and the other in the rear (2 fans),

providing the required ventilation.

The system has a chassis mid-plane with processing cards in the front and cable

connections in the back (excluding the optical GigE ports). This design allows rapid

card replacement without necessitating cable detachment and re-attachment. The

design also prevents errors caused by improper cable reattachment.

The shelf is designed with a system alarm card that provides monitoring, control,

status and alarming features. The system alarm card is placed in the rear side of the

shelf and centralizes the shelf alarms.

Figure 8: The 8U shelf


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Figure 9:The 4U shelf

3.7.2 The System Alarm CardThe shelf is designed with a system alarm card that provides monitoring, control,

status and alarming features.

The system alarm card monitors the status of the cPCI slots, fans and fan trays,

power supply input and output voltages and temperature. The power supplies, dry

contacts and four faceplate LEDs may be controlled remotely (via the GCC), and

each cPCI slot can be individually reset remotely (via the GCC).

If a failure occurs in either the power supply or the fan shelf, the system alarm card

sends alarm messages to the active GCC pack on the shelf. The active GCC pack

forwards the alarms messages as SNMP traps to the remote management station.

3.7.3 The Processing Cards

Two distinct types of processing cards is available:

Gateway Controller and Switch Cards - GCC

Gateway Media CardsGMC

These cards is placed in the free slots on the front part of the shelf with their

associated rear-transition modules (RTM) in the equivalent location in the back. All

interface ports and cables (excluding the optical GigE ports) is places on the reartransition modules.

3.7.3.1. The Gateway Controller and Switch Card (GCC)

A single Duet 9015 system contains one or two GCC cards. If two are present, the

second GCC card provides 1+1 redundancy (for more details about the GCC

redundancy, please refer to section Error! Reference source not found. "Error!

Reference source not found." on page Error! Bookmark not defined.).

The GCC pack is the system's main processor card, the core of the system, and

contains most of the system "intelligence". It connects to the IP backbone via a

100/1000 Base-T or an optical GigE and to the operator's back-office network via a10/100 Base-T interface link.


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As the system's processor, it performs, among others, the following functions:

MF/CAS Signaling Gateway

H.248-controlled Media Gateway

M2UA, IUA and SCTP stacks of the Signaling Gateway

Resources Management including the management of the VoIP resources onthe provisioned GMC cards.

Management and Provisioning (CLI, SNMP, SSHv2, Telnet, etc.)

Performance Monitoring (OMs, etc.)

DNS Client

NTP Client

Synchronization System management

File Server (EFD)

3.7.3.2. The Gateway Media Card (GMC)

The GMC card, is controlled by the GCC, and handles all the media processing. The

GMC is equipped with a dedicated VoIP DSP array.

Like the GCC card, the GMC card is placed in the front part of the shelf, its rear-

transition module placed in the associated location on the back side of the shelf.

The exact number of GMC cards per shelf varies depends on the required E1/T1s

capacity. Please refer to the engineering rules in Error! Reference source not found."Error! Reference source not found." on page Error! Bookmark not defined. for a

detailed description. The GMC accesses the IP backbone via the GCC.

The GMC performs, among others the following functions:

SS7 and PRI Layer 2 termination function of the Signaling Gateways

MF/CAS termination function of the Signaling Gateway

Media Coding: VoIP codecs

RTP/RTCP (encoding, decoding and stream disruption mechanisms).

DTMF detection and generation.

Echo cancellers.

VAD, Silence Suppression and Comfort Noise Generation.

Other media processing functions (refer to section3.5 on page26).

For a description of the GMC options, please refer to Error! Reference source not

found. "Error! Reference source not found." on page Error! Bookmark not defined..

3.7.4 The Duet 9015 System

Using the above described components, we can define the "Duet 9015 System".A Duet system is a combination of at least one GCC card and at least one GMC


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card placed in a Duet shelf and interoperating to provide the trunk/media gateway

service. Up to two GCC cards can be configured per system and the maximum

number of GMC cards per system depends on the required E1/T1s capacity. Duet

9015 with full capacity can support up to 128 E1/T1s (i.e. 4096/3072 DS0s).

The following figure describes a typical installation of a Duet 9015 system.

Backplane

Rear

Front

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

100/1000BaseT

GCC

E1/T1Interface

GMC

GCC

100/1000BaseT

E1/T1Interface

E1/T1Interface

E1/T1Interface

E1/T1Interface

GMC

GMC

StandbyGM

C

E1/T1Interface

E1/T1Interface

E1/T1

Links

Switch/Router

Backbone

Switch/Router

Backbone

GigE

GMC

E1/T1Interface

Backplane

Rear

Front

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

GMC

100/1000BaseT

GCC

E1/T1Interface

GMC

GCC

100/1000BaseT

E1/T1Interface

E1/T1Interface

E1/T1Interface

E1/T1Interface

GMC

GMC

StandbyGM

C

E1/T1Interface

E1/T1Interface

E1/T1

Links

Switch/Router

Backbone

Switch/Router

Backbone

Switch/Router

Backbone

GigE

GMC

E1/T1Interface

Figure 10: The Duet 9015 System

3.7.5 The Switch/Router

The Duet is connected to the IP backbone only via its GCCs. The GCCs areconnected to the IP backbone via an external Switch/Router. The Duet may have a

single IP address for the media and signaling traffic (IP-t) or different IP addresses

for the media, signaling and management traffic. The two GCCs, although each one

has its own network interface, share the same IP-t addresses: only the active card

uses the IP-t addresses and it moves to the standby card in case of a switchover (e.g.

due to a failure of the active GCC).

NOTE: The Switch/Router is not regarded as a part of the system.


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3.7.6 Reliability, Availability and Redundancy

3.7.6.1. GCC Redundancy

The Duet is a carrier-grade product. As such, the Duet 9015 does not present any

"single point of failure" in its architecture. This is achieved by providing (among

other things) the possibility to configure the system with two GCCs. Whenconfigured with two GCCs, one of the GCCs is the primary card performing all the

call process, resource allocation, management, etc. while the secondary processor

card is in a hot-standby mode, ready to take over at any sign of failure from the

primary processor. The two cards exchange between them, in real time, all the

information required to maintain the system activity, sanity and provisioning when a

switch over occurs.

The two GCCs have the same IP addresses for the signaling and media paths or the

signaling, media and management paths (configuration dependent). This way the

external world is not affected by a switchover. In case of a switchover the new

active GCC informs the L2 network that the traffic to the Duet is to be routed to theMAC address of its Ethernet port rather than the MAC address of the failed GCC's

port. This is done by the new active GCC sending a GARP message (Generic

Attribute Registration Protocol).

The switch over process between the two GCC cards does not impact the active

connections and the voice stream. Connection in setup stage may be dropped during

the switchover.

Management

Under normal operation, all the management functions/actions is performed via the

Active GCC board. The latest continuously updates the backup GCC card to ensurethat the two boards are synchronized. A database integrity check mechanism,

executed at predefined intervals, and an error recovery mechanism ensures the

integrity and the perfect synchronization of the management and configuration

databases stored on each GCC card.

The above described mechanism ensures that in the case of failure of the active

GCC card, the backup GCC card has an up to date image of the system status and is

fully capable of taking over the OAM&P function.

Please notice that after a switchover, all OAM&P operations are to be performed via

the new active GCC and its IP address (which is different from the active GCC IP

address).

3.7.6.2. GMC Redundancy

The Duet provides GMC 1:N redundancy. The administrator has the possibility to

add a supplementary GMC per shelf which is used only in case of a failure of one of

the other GMCs. Upon a GMC failure, the redundant GMC takes control on the

calls that were handled by the faulty GMC.

The redundant GMC, as the other GMCs, has an IP for management (IP-m) but has

nopublic IP for the traffic. The GCC replaces IP-m of the redundant GMC's RTP

and RTCP packets sent to the IP network with the single IP address for traffic (IP-t).

Thus, the external world is not affected by the switchover of the faulty GMC's calls

to the redundant GMC.


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The switchover process does not drop active calls and does not have an impact onthe voice stream.

Reversion back to the original configuration is provisionable, with the default of

happening automatically after the failure is recovered through a maintenance action,

and the option of waiting for a later time.

The Duet is h/w ready to provide also GMC 1+1 redundancy. However, the support

of this redundancy configuration is left to a future phase.

3.7.7 Power Supply Redundancy

The DC versions have two feeds distributed to three (4U) or four (8U) power

supplies. The AC version (4U) has a single feed. The AC power connections can be

non-redundant, since a high availability configuration would use a UPS with more

than one feed.

The power supplies are 1:N spared. When equipped with three power supplies, theDuet provides full power supply redundancy. Under normal operation, the power

supply units share the load. If a power supply unit fails, the remaining units takes

the entire load and the failure has no impact on the traffic and service level. The

alarm card detects the failure of a Power Supply pack and notifies the active GCC

card.


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Chapter 4 Technical Specifications

4.1 Capacity and ConfigurationThe Duet 9015 is provided in two different shelf configurations:

4.1.1 Large configuration Duet 9015L

Packed in a 8U, 19 Compact Peripheral Component Interconnection (cPCI) 2.16

shelf. The Duet 9015L is available with either DC input voltages, with a load-

sharing 3+1 redundant power supply configuration. The shelf has 17 physical pack

slots for standard 6U packs. The shelf is designed with a system alarm card that

provides monitoring, control, status and alarming features. Six blowers is placed in

the shelf: three above the 6U cards cage and three under 6U cards cage, to providethe required ventilation. The following picture shows the Duet shelf enclosure.

The 4 power supplies are located in the right front side of the shelf. The following

pictures show the Duet shelf enclosure.

The current design can accommodate two GCCs and up to 9 GMCs in 1:N

redundancy scheme, supporting all together up to 128 E1/T1s and up to 3968/3072

simultaneous trunks.

The shelf is h/w ready to support up to 11+1 GMCs (i.e. 176 E1/T1s).

The support of the GMC 1+1 configuration is left to a future phase.

4.1.2 Small configuration

Packed in a 4U, 19 Compact Peripheral Component Interconnection (cPCI) 2.16

compliant shelf. The small shelf is available with either AC or DC input voltages,

with a load-sharing 2+1 redundant power supply configuration. It has eight slots for

use with both front and rear transition cards. Of the eight slots, two are used for dual

redundant GCC, leaving six slots for the GMCs. The shelf is designed with a system

alarm card that provides monitoring, control, status and alarming features. The shelf

contains also fans, which provide the required ventilation for the 6U front cards andtheir RTMs. All the packs, including the Fans and the Power supplies are field

replaceable units (FRU). The following picture shows the 9015S enclosure.


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The Duet 9015S supports up to 48 E1/T1s in the GMC 1+1 configuration and 80

E1/T1s in the 1:N, (i.e. 1488/1152 trunks or 2480/1920). The shelf may be equipped

with only two Power Supply boards, and controlled by only one GCC board.Redundant power supply and

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CM9015 Product Descriptions

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