Introduction...............................................................................................3

VoPacket Drivers .......................................................................................3

How it works ..............................................................................................4

Why Marconi .............................................................................................5

Legacy PSTN .............................................................................................7

Evolution to VoIP.......................................................................................7

Tech Details..............................................................................................10

Acronyms .................................................................................................11

Introduction The combined forces of deregulation and broadband technologies have created unprecedented opportunities for service providers to maximize their revenues by offering new and exciting services. This is particularly true for the access portion of the network, also known as the local loop, where the introduction of the DSL technology has brought new momentum to the copper based infrastructure, paving also the way to competition in a market that was historically owned by the incumbent operators. Despite the huge increase in data traffic (internet/intranet access) that weve experienced over the past five years, voice still represents the major source of revenues for the vast majority of network operators involved in both the residential and business markets.

For such reason, this traditional service that has gone through more than a hundred years of history without knowing major technological enhancements (at least in its fundamentals), is now interested by the introduction of the new technologies pushed by the increased competition. The emerging operators willing to steal market portions to the incumbent, need to position themselves with new value-added services in order to persuade telephone users to subscribe; key issues are:

a comprehensive voice & data service package multiple telephone lines collateral services (three way part/conference call, CLIP, etc) last but not least, a competitive price

As far as voice is concerned, the predominance of TDM switches will decline over time, and be replaced by packet based core infrastructures. As this happens, the conversion of media and signaling between the Access layer and the new Core is required. A number of possibilities arise according to different deployment scenarios, fully supported by the equipment proposed by Marconi.

VoPacket Drivers The way ahead for communications is with a network architecture that is capable of delivering the multimedia applications of the future and todays narrowband telephony features. In this new network, the worlds of voice, data and video communications will converge into one Multi-Service Network, where all the critical components of communication are fused together. The same network that carries telephony services will also support the multimedia technology that will shape the future. The best of all possible worlds includes:

A single network for Voice, Data and Video services. As secure as the existing public voice networks. Reliable, delivering the same level of availability as the existing public telephone network. Scaleable, Networks starting small and then growing, over time, by the addition of capacity or features, to become great public networks with millions of customers. Future proof, capable of supporting change, in both business and technical environments, quickly, simply and without wholesale replacement.

The process of moving towards this new integrated world has already started by moving voice from analogue to packet based and is proceeding through a number of steps driven by availability of new technologies and market requirements. As we move towards a multi-service network the challenge is to find a way to move smoothly from the traditional vision to the new, whilst maximizing the yield of investment in infrastructure, by deploying a network solution which can support future needs. The architecture must be based on internationally recognized and accepted standards and be able to operate in a multi-vendor environment. Making use of new / up coming technologies converting voice into packet, must happen whether the end-user have chosen this technology and is bearing the cost of this capability (IAD) or whether it is unknown to him (direct voice).

How it works In order to maximize the Operators investment in the network infrastructure, it is particularly important to deploy a future proof solution with a well-defined evolution path to the Next Generation Network (NGN) architecture, providing also seamless integration with the outside world by fully supporting the relevant international standards. This concept is at the core of the Marconi philosophy, that is the ability to support a comprehensive range of todays and tomorrow services on a unique equipment platform. The convergence of traditional voice and data networks onto a single packet-switched infrastructure allows a Network Operator to realise significant

cost savings by only managing and maintaining one single network. However, the real value that is added by means of this migration is the possibility to create new, innovative multimedia services by combining voice, video and data in a way that was not possible with the separate networks, while at the same time consolidating the network interface to the core simplifying the rollout.

In the frame of the Next Generation Network, the term SoftSwitch is generally used to define the next generation switching solution. It provides functionality that is equivalent to the current local (Class 5) and trunk (Class 4) telephone exchange.

The main feature of the SoftSwitch is that instead of carrying voice as conventional digital circuit it carries it as IP packets. Importantly, the SoftSwitch is asked to provide equivalent quality of service for voice to that provided by current telephone networks as well as provide the same set of telephony features (such as Call Forwarding and Call Barring).

In a Softswitch there is no physical switching of calls. Instead calls are routed between endpoints as streams of packets across an IP or ATM based data network. The SoftSwitch controls the VoIP Access Gateway that converts analog voice (POTS) or digital voice (ISDN) into packets near to the customers premises (IAD or MSAN/DSLAM). The SoftSwitch provides for connection of voice (media) as packets from the Access Gateway to the end point through a data network. If the endpoint is in the existing telephone network, then the media has to go

through an other Access Gateway that converts packets to circuit again. The SoftSwitch also has to provide the other functions provided by traditional switches such as announcements and the recording of information for charging purposes Unlike traditional switches, which are programmed in the design phase by the switch vendor, SoftSwitches usually allow for a high level of programming service extension by the network operator.

Network evolution

Why Marconi Thanks to the great experience in voice switching and in Telecommunications Networks worldwide, Marconi is the ideal partner for deploying a future-proof access infrastructure enabling the Network Operator to provide a comprehensive range of services to its customers. The solution proposed by Marconi is based on the Access Hub (AXH) combined with the XCD5000 SoftSwitch platform.

The AXH equipment The Marconi Access Hub (AXH) is a multiservice platform that is designed to meet today's DSL requirements cost effectively, as well as to provide a

scalable platform (40Gb/s backplane) for the integration of IP function ality and support of bandwidth hungry services. The design is predicated on the view that there will be a mix of access technologies required in order to meet the future needs of Service Providers. Furthermore, it is critical that current revenue streams a re also supported by any new Access deployments. The AXH product range therefore supports a wide range of interface card types capable of addressing these needs.

The AXH product family makes it possible to configure economically efficient solutions for a wide range of applications, but with a common element and Network management infrastructure. The AXH also offers all the benefits ATM brings to multiservice networks including efficient bandwidth management and high availability; the compact, flexible design gives lower installation, operational and maintenance costs and efficient use of space.

The switching performances are coupled with a very high port density (top class in the market) as well as a wide choice of interfaces, to best fit each scenario. The Marconi AXH equipment supports the following range of interfaces:

ADSL SHDSL POTS ISDN Combined ADSL/POTS Combined VDSL/POTS E1 ATM/IMA E1 Circuit Emulation E3 ATM STM-1 ATM STM-4 ATM Giga-Ethernet

The AXH platform supports different ways of providing voice services, ranging from VoDSL (according to the BLES standard) to traditional TDM-based POTS and ISDN direct termination. Despite the different nature of these services (native ATM & native TDM), theyre all transported via the same Data (ATM/IP) based backbone, avoiding duplicated backhaul infrastructure.

Derived Voice Marconi is able to provide a complete VoDSL (BLES) solution including the AXH and the V5 - BLES Voice Gateway (HEG), and to suggest the most suitable IADs.

Traditional Voice/TDM i/f The AXH can also provide traditional TDM-based POTS and ISDN interfaces from the chassis: such a solution provides both V5.1 and V5.2 signalling on every node (independent of the size). The POTS services are mapped to Data through the on board packetization of the TDM-stream then sent to backplane until terminated into V5.2 card or to an E1 CES card (if the required signaling protocol is V5.1) for connection to the Class 5 Switch.

Moreover, the AXH is capable of supporting the Voice transport functionality through Circuit Emulation Services. Beyond the pure Voice Transport as delivered by existing DLCs, it is avoiding the need to have two separate infrastructures in the core, by introducing the flexibility to choose between an SDH vs. ATM Access Network. The transport of the narrowband TDM based services via the ATM links is realized by the Circuit Emulation card. This card

emulates E1 circuits over ATM cells, thus utilizing the ATM network while respecting the time and delay constraints of the TDM traffic. Despite the relevant change in the network concept, no additional equipment is required enabling a cost-effective migration towards a fully packet-based network.

A Revolutionary Platform Coming back to the TDM-based services, in addition to the 60 x POTS and the 30 x ISDN cards, a revolutionary access technology is available on the AXH. The AXH is capable of hosting 24 x POTS/xDSL Combo card (xDSL standing for ADSL or VDSL), where every single line can be configured as POTS, xDSL or POTS+xDSL. This offers significant benefits as the penetration of broadband service increases and is especially suited to operators wanting to migrate their core and access networks to an all-packet architecture.

Picture: the 24x xDSL/POTS card

The benefits of the new Combo card apply when it is deployed as an extension to existing voice infrastructure, serving new customers with bundled services (xDSL + POTS), as well as for green field applications in new development areas, where it is reasonable to accept a potential

migration of end user ultimately to Broadband.

AXH TDM-based POTS and ISDN cards are already open to evolve to an all IP-based concept (HW support for AAL5 on the Combo, POTS and ISDN cards today; full functionality will be available by software download).

The following principles are at the basis of the current solution:

The voice traffic is transformed into packet/cells directly on the subscriber line cards, providing a platform where all the services are integrated into a Network Element. Depending on transport network and the PSTN/Softswitch hand over point the scenario varies

Next Generation Multi Service Application Platform

Legacy PSTN With Legacy PSTN the telephony signaling is V5 standard and native, directly terminated on the subscriber line cards. AAL1 CES is used between subscriber line cards and V5.2 signaling module (V5-card), located where concentration needs to be applied (every node or centralized POP). Into the V5.2 signaling module CES streams are transformed back (from ATM to TDM) and presented to a LE

Class 5 as V5.1 or V5.2 interfaces (in the case of V5.1 an even simpler realization could be achieved with the 16xE1 CES Card). Summarizing, the solution is based on the transport of one or more 2Mbps TDM streams with V5.1 signaling from the line cards to the V5.2 signaling module, using AAL1 CES, applying concentration and interfacing either directly to the PSTN via V5 or mapping back the now concentrated voice into the DSLAM uplink.

As a future proof platform, this design is able to support the future upgrade of the network towards VoIP support.

The subscriber cards are designed with DSP resources on board that can be used for transforming voice into IP packets directly on the cards themselves. This allow a very cost effective evolution for integrating narrowband services in a future IP network, where the gateway function (converting from TDM to packet) is distributed directly on end user ports. This solution is optimized for operators who offer mixed services today (narrowband and broadband) and have intentions to move to a VoIP architecture (from core to edge) in the future. By means of software upgrade, the same subscriber cards can be used for generating V5 traffic today, and VoIP tomorrow.

Evolution to VoIP The purpose of Marconi's efforts is the ability to provide a cost-effective evolutionary path to enhanced services solutions. The Marconi Broadband Access solution supports packet based access networks capable to support both TDM based and packet based

voice traffic, the latter controlled by soft-switches, featuring the following:

Media services: such as echo cancellation, tone generation, DTMF, Caller-ID or call-waiting Feature Services: these include multi-way calling, announcement server interconnectivity, law-enforcement support, emergency stand-alone operations and emergency (911) trunking support. Signaling Services providing a unified representation of distributed call entities (such as IAD devices) by directly interfacing with softswitches. This feature simplifies the network management.

The Marconi architecture includes interfaces to soft-switches and application servers. These interfaces support signaling protocols such as MGCP and H.248 (MeGaCo), enabling a smooth evolution path towards a Next Generation Network based on a full-IP infrastructure, providing all kinds of services (voice, video, data, etc) to end users.

The AXH Voice cards already take this into account, as they can support AAL5 functionality by software upgrade. The voice media packetization will be done directly on the Subscriber card, this implies: Subs card is capable of transforming PCM voice into packets (VoIP/AAL5) and supporting all the main requirements for voice-over-packet such as: voice coding and compression (G711, G726, G729), silence suppression and noise generation, echo cancellation, fax and modem transport etc.

In case of a full packet voice solution, no other Media Gateways are elsewhere necessary in the network. Effectively the architecture is implementing the Media Gateway function for all voice traffic in a distributed way directly on the Subscriber cards.

The Access Hub ensures that Voice Cells are given priority and are switched through (initial option being via ATM, via GigE interface in a further step) to the SoftSwitch core router network. The SoftSwitch Call Agent (SCA) provides Call-control using MGCP, and interfacing to other VoIP networks is achieved via Media Firewalls. These equipments control the access, the used bandwidth and the QoS policy into the SoftSwitch.

An advantage of evolving the AXH-voice solution from V5.x to voice-over-packet is the additional capability of the last to re-route internally local traffic from two user ports subtended by the same system. This reintroduces the capability for local switching (even if commanded by a centralized Call control device) into the Access Nodes.

In the following, a complete network architecture for a Next Generation Network handling VoIP is depicted: the softswitch components are introduced in the following section.

IAD

DSLLINKS

VoIP

VoATM(BLES)

POTS

IAD

NT

1)

2)

3)

AAL1(V5.X)

AAL5

AXH

H.248/MGCP

ServiceOnAccess

AXH

CE/V5.2

V5.x

PSTN

Class 5Switch

Media/SignalingGatewayHEG

xDSL cards

Combo* card/ POTS / I SDN

MediaFW

CallAgent

IPCore

Softswitch

Announc.Server

Next Generation Network (NGN) evolution

Marconi XCD5000Softswitch The Marconi XCD5000 SoftSwitch is built around the concept of a SoftSwitch Zone. The Zone defines the area of control of the SoftSwitch and its component parts. It does not define a geographical region or a specific network topology. The architecture for the Marconi SoftSwitch Zone is shown below in the figure below.

PSTN

ManagementSystem

Call Agent

AnnouncementSubsystem

IPNetwork

Media Firewall

MediaFirewall

SoftSwitchZone

MediaGateway

SignallingGateway

RouterNetwork

The Marconi XCD5000 SoftSwitch is composed of the following components.

The Call Agent is the heart of the system, providing all the accepted industry-standard functions - user authentication, call routing, call detail record generation, IP address translation, and support for Telephony supplementary features running on a standard UnixTM platform. The Media Gateway directs real-time, two-way communications between IP networks and circuit-switched (PSTN) networks. It performs media conversion, detects changes in media streams, and detects tones using the latest DSP technology. The Signaling Gateway shares common hardware with the Media Gateway and offers the signaling interface between C7/SS7 networks and the SoftSwitch. The Announcement Subsystem provides service guidance tones and announcements. The Call Agent requests connection of tones or announcement to a specified

endpoint and the Announcement Subsystem streams them as packets to the destination. Announcements can be in multiple languages. The Media Firewall protects the integrity and security of resources and Network Operator data for the Zone Router network, allowing traffic through only under the direction of the SoftSwitch Call Agent.

The Marconi SoftSwitch is operated by a dedicated management system providing Network and Element Management for the SoftSwitch components via a graphical user interface, allowing for provisioning, billing and maintenance. The management system also supports a number of central servers that provide:

Management of software builds and data configuration Charging User management Secure data storage.

Tech Details

Features Basic (u-law PCM) ADPCM Raw mode

Classical EC_Freeze NLP

Echo Cancellation

Tone Disable Adaptive Echo Cancellation

selected tones NA-call progress International Tones

Tone processing

Programmable Duration DTMF Playback Recording Realtime Reload

Announcements

List Fixed level Comfort Noise

VAD+SID+CNG+ Silence Suppression

Adaptive Comfort Noise User Programmable Gain Control A-law option A-Law to u-Law Conversion Caller ID Multi-Digit Dialing ADPCM40/24/16 G.729A/B G.729 E G.728 G.723.1 AMR Fax/Modem Detection and reversion

Data pump T4, T.38

Fax-Relay

T4, , I.366.1 Long jitter buffer Adaptive jitter buffer

Voice Features

Programmable Jitter Buffer Threshold Basic (1*DS0 no CAS) N* DS0+CAS+S/U

Adaptive Clock Recovery

AAL1

SRTS RTP/UDP/IP/AAL5

CAS Tone

RTP-signaling transport

RTP-CCS/ISDN RTP/UDP/IP/POS-PHY RTP/UDP/IP/EN TCP/RTCP Transport

VoIP/ALL5

RFC 1483 - LLC SNAP

AAL1/IPoAAL5 selectable per chip AAL1/IPoAAL5 all on a Single chip (per ch)

Simultaneous NP

Basic NP Interworking Interrupt-mode Non Blocking

Line Provisioning in Stdby Mode Call Back Gen/Rcv Turn off I/F

Redundancy Support

Power Down TDM in TDM Out (PCM, Tones, EC, Ann.)

API/Misc

CALEA / Conferencing

Voice Interfaces Standards Features Specifications Physical connector Amp-Champ type connector Physical and Electrical characteristics ETS 300 001 Low frequencies transmission quality ETS 300 001 General Characteristics of Telephone Connections and Circuits

ITU-T G.165

Transmission characteristics ITU-T Q.552 Echo Cancellation ITU-T G.168 Modulation ITU-T G.711 (PCM)

Table 1 POTS interfaces characteristics

Features Specifications Physical connector Amp-Champ type connector Transmission characteristics G.961 Transmission and Multiplexing (TM) ETSI 102 080

Table 2 ISDN interfaces characteristics

Features Specifications Physical connector 75 or 120 connector Supported standards ETS 300 324 (V5.1)

ETS 300 347 (V5.2) Table 3 V5 interfaces characteristics

Acronyms AAA Authentication Authorization Accounting AAL2 ATM Adaptation Layer 2 ATM Asynchronous Transfer Mode BLES Broadband Loop Emulation Service B-RAS Broadband - Remote Access Server CLI Caller Line Identifier DSL Digital Subscriber Line DSLAM Digital Subscriber Line Access Multiplexer GUI Graphical User Interface HEG Head End Gateway ISP Internet Service Provider LAC L2TP Access Concentrator LE Local Exchange LNS L2TP Network Server MDF Main Distribution Frame MGCP Media Gateway Control Protocol NGN New Generation Network POTS Plain Old Telephone System PPG Packet to Packet gateway PPP Point to Point Protocol PSTN Public Switched Telephone Network QoS Quality of Service SIP Session Initiation Protocol TDM Time Division Multiplexing ULL Unbundling Local Loop VDSL Very High Speed Digital Subscriber Line VoDSL Voice over DSL VPN Virtual Private Network

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