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6. Next Generation Networks

6.1. Transition to NGN

6.2. Key drivers of NGN development

6.3. Evolution of networks’ architecture to NGN

6.4. NGN architecture

6.5. Main NGN protocols and building blocks

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6.1. Transition to NGN: First wave• Growth of Internet and other IP-based networks with their requirements for bandwidth and capacity has driven rapidinnovation in telecommunication access and transport networks Examples:– leveraging copper wire “last-mile” networks through digital

subscriber line (“DSL”) technologies– re-architecturing of cable networks to support IP services– advances in optical networking technologies (e.g. PON)

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Convergence of Telephony World and Internet World

4

Transition to NGN: Second wave

• Ongoing trend towards integration & interoperability of IP-based and PSTN network services and applications• Emergence of differentiated Quality of Service IP-based services• Managed end-to-end performance needed for new applications requiring real-time traffic (e.g., video, voice)• New network management, QoS, traffic engineering, pricing & accounting models

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Transition to NGN: Third wave

• Evolution of current PSTN, mobile, wireless and IP-based networks to unified Next Generation Networks providing both Internet and carrier-grade telecommunications networks and services offerings with QoS• Transition to Third wave: Ubiquitous & Pervasive Networks– anybody, anytime, anywhere• Global Information Infrastructure (GII) – ITU, 1995• EII ETSI Project (1995)• ETSI – 3GPP (1998) • 3GPP activity (FMC and IMS development)• TISPAN Project (ETSI, 2003) TISPAN - Telecoms & Internet converged Services & Protocols for

Advanced Networks • ITU NGN 2004 Project• Y.1xx ITU-T – SG 13 “NGN – Architecture, Evolution and Convergence”

6One unified network for everything

TodayToday TomorrowTomorrow

Telephonenetwork

Mobile radionetwork

IP-Network

Multimedia Access - Advantages:• easy to handle• reliable• mobile

Internet

Transition to NGN: Third wave

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The Unified NetworkThe Vision

Situation TodaySituation Today Target SolutionTarget Solution

VoiceFix and Mobile

VoiceFix and Mobile

FRFR

IPIP

ATMATM

......

The Unified Multi Service

Network

The Unified Multi Service

Network

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The Unified NetworkThe Data Migration

VoiceVoice

FRFR

IPIP

ATMATM

......

The Unified Multi Service

Network

The Unified Multi Service

Network

Pure technology/standardization matter:How different data services

can transport over a unique data backbone

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The Unified NetworkThe Voice Migration

VoiceVoice

FRFR

IPIP

ATMATM

......

The Unified Multi Service

Network

The Unified Multi Service

Network

Somewhat more complex- From circuit switched to packet switched

- Voice switches need to disappear in the long term

A new network concept supporting voice in a packetized environment is required The Next Generation Network

A new network concept supporting voice in a packetized environment is required The Next Generation Network

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ITU-T definition of NGN (Y.2001, Feb 2004)

“A Next Generation Network (NGN) is a packet-based network

able to provide services including Telecommunications Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functionsare independent from underlying transport-related technologies. It offers unrestricted access by users to different service providers. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.”

One of the primary goals of NGN is to provide a common, unified, and flexible service architecture that can support multiple types of services over multiple types of transport networks.

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NGN is the public packet-based network with the following main features:

– Layered architecture

– Open interfaces between the layers and all other networks

– Seamless control of multiple transport technologies

– Centralized intelligence

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NGN Characteristics

The NGN is characterized by the following fundamental aspects:• Packet-based transfer in the core NGN network• Support for a wide range of services, applications and mechanisms (including real time/ streaming/ non-real time services and multi-media)• Independence of service-related functions from underlying transport technologies• Separation of control functions among bearer capabilities, call/session, and applications/services• Broadband capabilities with required end-to-end QoS• Interworking with legacy networks via open interfaces• Generalized mobility• Unrestricted access by users to different service providers• Services convergence between Fixed/Mobile• Compliance with all Regulatory requirements, for example concerning

emergency communications, security/privacy, etc.

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6.2. Key drivers of NGN development

• Short Term objective: Create new revenue possibilities– Removal of boundaries between voice and data opens

the way to new kind of services– Can be realized relatively quickly with limited

investments

• Long Term objective: Realize cost savings – Simpler network – More efficient network– Cheaper network components– Full benefit only realized when all separate networks

have fully migrated towards to the target solution

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Driven byCost Reduction

Possibilities

Driven byRevenue Increase

Possibilities

Key drivers: technologies and services

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• User demands– easiness to use and personalization of services– seamless service regardless of the access technology– a “beautiful garden” offering valuable services with security– openness to the entire Community

• Operator challenges need to be addressed– need to manage complexity to deliver simplicity– platform for convergence of services and technologies– support of different device and access technologies– revenue opportunities by mobility and nomadicity, worldwide

use– support migration from existing technologies

NGN key drivers: From IP Technology to User and Application

Centric

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NGN services

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NGN Services• Voice Telephony – NGN will likely need to support various existing voice telephonyservices (e.g., Call Waiting, Call Forwarding, 3-Way Calling, various IN features, various Centrex features and etc.). • Data Services – Allows for the real-time establishment of connectivity between endpoints, along with various value-added features

• Multimedia Services – Allows multiple parties to interact using voice, video, and/or data.

• Virtual Private Networks (VPNs) – Voice VPNs improve the interlocation networkingcapabilities of businesses by allowing large, geographically dispersed organizations tocombine their existing private networks with portions of the PSTN, thus providingsubscribers with uniform dialing capabilities.

.

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NGN Services• Public Network Computing (PNC) – Provides public

network-based computing services for businesses and

consumers.

• Unified Messaging – Supports the delivery of voice mail, email,

fax mail, and pages through common interfaces.

• Information Brokering – Involves advertising, finding, and

providing information to match consumers with providers. • E-Commerce – Allows consumers to purchase goods and

services electronically over the network. Home banking and

home shopping fall into this category of services. This also

includes business-to-business applications

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NGN Services

• Call Center/Web Contact Services – A subscriber could place a call to a call/Web contact center agent by clicking on a Web page.

• Interactive gaming – Offers consumers a way to meet online and establish interactive gaming sessions (e.g., video games).

• Distributed Virtual Reality – Refers to technologically generated representations of real world events, people, places, experiences, etc.,

• Home Manager – With the advent of in-home networking and intelligent appliances, these services could monitor and control home security systems, energy systems, home entertainment systems, and other home appliances.

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Applications• VoIP • Web Browsing• Chat• Instant Messaging• WAP Browsing• Multimedia Messaging• VoD – Movies/Gaming/News/Sports/Training• Video Telephony• Video Broadcasting• Video Conferencing• Video Collaboration• IP PBX/Centrex• Email

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NGN Today: Facing the Multi-Application/Multi-Access Challenge

Conversational real-time communication

Web, email,chat, etc.

Video on Demand(VoD)

High Definition TV(HDTV)

Gaming

Smart Home

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6.3. Evolution of networks’ architecture to NGN

• The unified network will use packet-based technology as the common transport mechanism– Data is the fastest growing segment due to

• Success of Internet• Growing use of E-mail• Growing data traffic between business users

– Data should be handled in the most efficient way– Packet technology is the best way to transport data– Packet technology is only technology that allows simultaneous

delivery of different information streams towards one and the same end-point on one single connection

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Evolution of network architecture •Traditional telephony - Circuit switch based PSTN

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Evolution of network architecture

• Circuit Switched PSTN + Packet Switched IP network (VoIP Gateway)

SG – Signaling gatewayMGC – Media gateway controllerMG – Media gateway

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Evolution of network architecture

•Completely IP-oriented network

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Convergence of network technologies and media

Nx64 kbps

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Packet NetworkPacket Network

UTRANUTRAN

Mobile Mobile PSTNPSTN

COCOCableCableDSLDSL

BroadbandBroadband

WLLWLLAccess

Edge

Core

Control

Applications

Management

MediaGateway

MediaGatewa

y

System Management Servers

ResidentialUsers

Remote Office/SOHOEnterprise Customers MobileUsers

Softswitches

Signaling gateways

Application Servers

6.4. NGN architecture

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Application/Management Part

Session Part(Call control)

Transport Layer

Open Services Interfaces/API

Media Gateway Control

…

NGN architecture - NGN functional model

Application ServersManagement Servers

Softswitches

…

Media Gateways

API - Application Programming Interface

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NGN architecture

IP network

SoftswitchApplication ServerNetwork Management

Server

Media GatewayMultiservice Access

PSTN, GSM, ATM, ...

Services

Transport

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ITU-T NGN architecture (Y.1001) and corresponding protocols

PSTN/ISDNIP Network IW Functions

IntelligentDatabase (ID)

Signaling Gateway (SG)

.

MG Controller(MGC)

Media Gateway(MG)

.

.

.. ID/SG

CC7/SS7ISUP

MGC/MG

RTP Packet Flow (Voice/Data/MM)

TDM Flow (Voice). .

.MGC/MGC

SG/MGC

ID/MGC

H.323/SIP/SIP-T/SIGTRAN

API

MGCP/Megaco(H.248)

.

•Softswitch includes MGC, SG•Media Gateway is protocol converter•Media Gateway Controller is master controller of a media gateway•Intelligent Database - Network directory,Billing, Call records

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6.5. Main NGN protocols and building blocks

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A. Main control protocols

Call Control (Session Control)The ability of a network element to establish new calls.

A “call” in the next generation network can be viewed as

a session in which the session establishes either a voice

conversation or, ultimately, a multimedia (audio plus video)

stream.

There are two primary call control protocols unique to

packet-based networks:

H.323

SIP

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H.323, ITU-T

• H.323 - first call control standard for multimedia networks. Was adopted for VoIP by the ITU in 1996• H.323 is actually a set of recommendations that define how voice, data and video are transmitted over IP-based networks • The H.323 recommendation is made up of multiple call control protocols. The audio streams are transacted using the

RTP/RTCP • In general, H.323 was too broad standard without sufficient efficiency. It also does not guarantee business voice quality

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SIP - Session Initiation Protocol, IETF (Internet Engineering Task Force)

• SIP - standard protocol for initiating an interactive user session that involves multimedia elements such as video, voice, chat, gaming, and virtual reality. Protocol claims to deliver faster call-establishment times.

• SIP works in the Session layer of IETF/OSI model. SIP can establish multimedia sessions or Internet telephony calls. SIP can also invite participants to unicast or multicast sessions.

• SIP supports name mapping and redirection services. It makes it possible for users to initiate and receive communications and services from any location, and for networks to identify the users wherever they are.

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SIP - Session Initiation Protocol, IETF

•SIP – client-server protocol, Rq from clients, Rs from servers. Participants are identified by SIP URLs. Requests can be sent through any transport protocol, such as UDP, or TCP.

•SIP defines the end system to be used for the session, the communication media and media parameters, and the called party's desire to participate in the communication.

•Once these are assured, SIP establishes call parameters at either end of the communication, and handles call transfer and termination.

•The Session Initiation Protocol is specified in IETF Request for Comments (RFC) 2543.

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IN Control

Feature servers provide IN control with legacy central

offices and Softswitches.

INAP (Intelligent Network Application Part) - a member

of the family of SS7 application protocols.

Additional IN protocols have also been developed

for mobile networks (e.g. GSM-CAMEL).

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Gateway control

The target of the Gateway control - to enable a simple

media gateway implementation with intelligence

centralized on a media gateway controller (which is also

called a call agent or a Softswitch)

Two gateway control protocols:

Media Gateway Control Protocol (MGCP) as the de

facto standard

H.248/Megaco as the ITU and IETF approved standard.

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MGCP/Megaco/H.248

• MGCP - Media Gateway Control Protocol, IETF [Telcordia (formerly Bellcore)/Level 3/Cisco]

• MGCP – control protocol that specifically addresses the control of media gateways

• Megaco/H.248 (IETF, ITU) - standard that combines elements of the MGCP and the H.323, ITU (H.248)

• The main features of Megaco - scaling (H.323) and multimedia conferencing (MGCP)

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Media Control

Media control is a form of device control used for network

elements that are specialized for advanced media processing.

Media control includes instructions to play and record voice

files, collect and generate tones (including DTMF touch-tones),

establish N-way conferences, perform fax conversions, generate

text-to-speech, and perform speech recognition.

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Application Program Interface

API - routing, billing, call control, and media control on the feature server and application server. The goal of the APIs is to enable:1. Service logic that is independent of network protocols, network deployment architecture, and reference element architecture to meet the service provider requirement for service ubiquity2. Services that scale from an entry level integrated solution to a distributed network deployment without modifications, meeting the service provider requirement for low cost infrastructure

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Main transport protocols

Real-Time Transport Protocol (RTP) and Real-Time Control Protocol (RTCP)

RTP - for end-to-end network transport of communications services requiring real-time data (i.e., audio and/or video).

Real-Time Control Protocol (RTCP) – for data transport monitoring RTP and RTCP are designed to be independent of the underlying network layers (e.g., UDP/IP, MPLS, or ATM).

RTP does not address resource reservation nor does it guarantee quality-of-service (QoS).

Resource Reservation Setup Protocol (RSVP)

Multi-Protocol Label Switching (MPLS) RTP routing over MPLS sessions

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NGN architecture – possible NGN configuration

H.323/SIP

SG

Mobile Networks/IMS

Media Gateway

Network Manager

ID AAA

SS7Switch STP

PSTN/ISDN

SS7Switch STP

PSTN/ISDN

Media Gateway

Core IP Network (QoS)

Gatekeeper/Proxy Server

API (Parlay, LDAP)

Application Server

MGCP/Megaco/H.248

SIGTRAN SIGTRAN

Н.323/ IP Network

SS7 ISUP

SIP/SIP-TH.323/BICC

RADIUS

ISUP

SIP Softswitch

SG

Softswitch

MGC

SNMP

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B. NGN building blocks• Media Gateway - protocol converter• Media Gateway Controller - master controller of a

media gateway• Softswitch = MGC + SG• Signaling Gateway• Application Server – Information Database (ID) -

Network directory, Billing, Call records, Authentication, authorization, and accounting (AAA)

• Network Manager – Operation, Administration, Management (OAM); provides network elements’ management from a centralized web interface

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Media Gateway (IETF RFC 3015)

Media gateway (MG) – protocol converter between different types

of networks (Example – MG between circuit-switched voice

network - TDM flows, and the IP network - RTP packet flows.)

MG processes incoming calls via requests to the Application

Server using HTTP.

The media gateway (MG) terminates IP and circuit-switched

traffic. MGs relay voice, fax, modem and ISDN data traffic over the

IP network using Quality of Service enabled IP technology.

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Media Gateway (IETF RFC 3015) • All types of traffic (voice, data, video)

• Control (from Media Gateway Controller): MGCP, Megaco/H.248

• Interfaces: STM-1to transport network, E1 to PSTN; Eth-Fast/Gb to IP network

• Voice Packetization/Compression (Codecs: ITU-T G.711, G.723.1, G.726, G.729A

• Echo cancellation: ITU-T G.165, G.168

• QoS via DiffServ and ToS bits marking

• Mapping addresses: E.164 IP address

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Softswitch Signaling GatewaySignaling Gateway (SG) offers a consolidated signaling

interface - SS7 signaling point for the NGN platform.

Also, SG supports a SIGTRAN interface (IETF SS7 telephony

signaling over IP) as well as IP Proxy functions (SIP).

Media Gateway Controller• MGC acts as the master controller of a media gateway• Supervises terminals attached to a network• Provides a registration of new terminals• Manages E.164 addresses among terminals

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Транспортная сеть

сигнализации IP SCTP/IP MTP

Транспортная сеть

сигнализации SS7

SGW

Signaling Gateway Function

SIGTRAN ISUPIP Signaling SS7 Signaling

IP Network PSTNSignaling Gateway

•Several millions BHCA•Several hundreds controlled trunk ports•Control: MGCP, MEGACO, SIP•Signaling: ISUP, H.323, SIP, SIP-T, INAP, SIGTRAN•Mgmt: SNMP

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Application server – provides the applications (i.e., service logic) for new and innovative services such as unified messaging, conferencing, speech dial tone, and multimedia messaging services. Application servers are typically based on advanced Java tool environments that provide multi-modal integration of voice and data.

Application Server generates application documents (VoiceXML pages) in response to requests from the Media Gateway via the internal Ethernet network.

The application server leverages a web application infrastructure to interface with data stores (messages stores, user profile databases, content servers) to generate documents (e.g., VoiceXML pages).

AS provide interoperability between applications like WAP, HTML, and voice allowing the end user to simultaneously input voice command and receive presentation via WAP or HTML.

Application Server

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Appendix A: Parlay

Parlay is an evolving set of specifications for industry-standard application programming interfaces (APIs) for managing network "edge" services:

• call control• messaging• content-based charging.

Parlay specifications are being developed by the Parlay Group, a consortium of member companies that include AT&T, BT, Cisco, IBM, Lucent, Microsoft, Nortel Networks, and others.

Use of the Parlay specifications is expected to make it easier to add new cross-platform network applications so that users need not depend solely on the proprietary offerings of carriers.

The Parlay Group is not a standards group itself, but sees itself as a facilitator of needed interfaces. Application program interfaces are or will be defined for:

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Parlay• Authentication • Integrity management • Operations, administration, and maintenance (OA&M) • Discovery (of the closest provider of a service) • Network control • Mobility • Performance management • Audit capabilities • Generic charging and billing • Policy management • Mobile M-commerce/E-commerce • Subscriber data/user profile/virtual home environment (VHE) • The Parlay APIs are said to complement and encourage use of the

Advanced Intelligent Network (AIN) protocols.

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Appendix B: Application level protocols

A. LDAP (Lightweight Directory Access Protocol)• LDAP (Lightweight Directory Access Protocol) is a software protocol for

enabling anyone to locate organizations, individuals, and other resources such as files and devices in a network, whether on the public Internet or on a corporate Intranet.

• LDAP is a "lightweight" (smaller amount of code) version of Directory Access Protocol (DAP), which is part of X.500, a standard for directory services in a network. LDAP is lighter because in its initial version it did not include security features.

• LDAP originated at the University of Michigan and has been endorsed by at least 40 companies. Netscape includes it in its latest Communicator suite of products. Microsoft includes it as part of what it calls Active Directory in a number of products including Outlook Express. Novell's NetWare Directory Services interoperates with LDAP. Cisco also supports it in its networking products.

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B. LDAP• In a network, a directory tells you where in the network something is located. On

TCP/IP networks (including the Internet), the domain name system (DNS) is the directory system used to relate the domain name to a specific network address (a unique location on the network). However, you may not know the domain name. LDAP allows you to search for an individual without knowing where they're located (although additional information will help with the search).

• An LDAP directory is organized in a simple "tree" hierarchy consisting of the following levels: # The root directory (the starting place or the source of the tree), which branches out to # Countries, each of which branches out to # Organizations, which branch out to # Organizational units (divisions, departments, and so forth), which branches out to (includes an

entry for) Individuals (which includes people, files, and shared resources such as printers)

• An LDAP directory can be distributed among many servers. Each server can have a replicated version of the total directory that is synchronized periodically. An LDAP server is called a Directory System Agent (DSA). An LDAP server that receives a request from a user takes responsibility for the request, passing it to other DSAs as necessary, but ensuring a single coordinated response for the user.

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B. Authentication, Authorization, Accounting (AAA) • Authentication, Authorization, Accounting (AAA) is a term for a framework for

intelligently controlling access to computer resources, enforcing policies, auditing usage, and providing the information necessary to bill for services. These combined processes are considered important for effective network management and security.

• As the first process, authentication provides a way of identifying a user, typically by having the user enter a valid user name and valid password before access is granted. The process of authentication is based on each user having a unique set of criteria for gaining access. The AAA server compares a user's authentication credentials with other user credentials stored in a database. If the credentials match, the user is granted access to the network. If the credentials are at variance, authentication fails and network access is denied.

• Following authentication, a user must gain authorization for doing certain tasks. After logging into a system, for instance, the user may try to issue commands. The authorization process determines whether the user has the authority to issue such commands. Simply put, authorization is the process of enforcing policies: determining what types or qualities of activities, resources, or services a user is permitted. Usually, authorization occurs within the context of authentication. Once you have authenticated a user, they may be authorized for different types of access or activity.

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B. Authentication, Authorization, Accounting (AAA)• The final term in the AAA framework is accounting, which measures the resources a

user consumes during access. This can include the amount of system time or the amount of data a user has sent and/or received during a session. Accounting is carried out by logging of session statistics and usage information and is used for authorization control, billing, trend analysis, resource utilization, and capacity planning activities.

• Authentication, authorization, and accounting services are often provided by a dedicated AAA server, a program that performs these functions. A current standard by which network access servers interface with the AAA server is the Remote Authentication Dial-In User Service (RADIUS).

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C. RADIUS

Remote Authentication Dial-In User Service (RADIUS) is a client/server protocol and software that enables remote access servers to communicate with a central server to authenticate dial-in users and authorize their access to the requested system or service. RADIUS allows a company to maintain user profiles in a central database that all remote servers can share. It provides better security, allowing a company to set up a policy that can be applied at a single administered network point. Having a central service also means that it's easier to track usage for billing and for keeping network statistics. Created by Livingston (now owned by Lucent), RADIUS is a de facto industry standard used by a number of network product companies and is a proposed IETF standard.

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Appendix C. Additional NGN signaling protocols

• SIP-T

• SIGTRAN

• BICC

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A. SIP-T

• SIP-T (SIP for telephones) is a mechanism that uses SIP to facilitate the interconnection of the PSTN with IP. SIP-T defines

SIP functions that map to ISUP interconnection requirements.• This is intended to allow traditional IN-type services to be

seamlessly handled in the Internet environment. It is essential that SS7 information be available at the points of PSTN interconnection to ensure transparency of features not otherwise supported in SIP. SS7 information should be available in its entirety and without any loss to the SIP network across the PSTN-IP interface.

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B. SIGTRAN

• SIGTRAN (for Signaling Transport) is the standard Telephony Protocol used to transport Signaling System 7 signals over the Internet. SS7 signals consist of special commands for handling a telephone call.

• The IETF Signaling Transport working group has developed SIGTRAN to address the transport of packet-based PSTN signaling over IP Networks, taking into account functional and performance requirements of the PSTN signaling. For interworking with PSTN, IP networks will need to transport signaling such as Q.931 or SS7 ISUP messages between IP nodes such as a Signaling Gateway and Media Gateway Controller or Media Gateway. Applications of SIGTRAN include Internet dial-up remote access and IP telephony interworking with PSTN.

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B. SIGTRAN

A telephone company switch transmits SS7 signals to a SG. The gateway, in turn, converts the signals into SIGTRAN packets for transmission over IP to either the next signaling gateway. The SIGTRAN protocol is actually made up of several components (this is what is sometimes referred to as a protocol stack): • standard IP• common signaling transport protocol (used to ensure that the data

required for signaling is delivered properly), such as the Streaming Control Transport Protocol (SCTP)

• adaptation protocol that supports "primitives" that are required by another protocols.

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C. Bearer Independent Call Control (BICC)

• Bearer Independent Call Control (BICC) is a signaling protocol based on N-ISUP that is used to support NB-ISDN service over a BB backbone network without interfering with interfaces to the existing network and end-to-end services. Specified by the ITU-T in recommendation Q.1901, BICC was designed to be fully compatible with existing networks and any system capable of carrying voice messages. BICC supports narrowband ISDN services independently of bearer and signaling message

transport technology.

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C. Bearer Independent Call Control (Cntd.) ISUP messages carry both call control and bearer control

information, identifying the physical bearer circuit by a Circuit Identification Code (CIC). However, CIC is specific to time-division multiplexed TDM networks. BICC was developed to be interoperable with any type of bearer, such as those based on asynchronous transfer mode ATM and IP technologies, as well as TDM.

BICC separates call control and bearer connection control, transporting BICC signaling independently of bearer control signaling. The actual bearer transport used is transparent to the BICC signaling protocol - BICC has no knowledge of the specific bearer technology.

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C. Bearer Independent Call Control (Cntd.)

• The ITU announced the completion of the second set of BICC protocols (BICC Capability Set 2, or CS 2) in July 2001; these are expected to help move networks from the current model - which is based on public-switching systems - to a server-based model. The BICC deployment architecture comprises a proxy server and a media gateway to support the current services over networks based on circuit-switched, ATM, and IP technologies, including third-generation wireless.

• The completion of the BICC protocols is an real and important ITU step toward broadband multimedia networks, because it will enable the seamless of circuit-switched TDM networks to high-capacity broadband multimedia networks. The 3GPP has included BICC CS 2 in the UMTS release 4. Among the future ITU-T plans for BICC are the inclusion of more advanced service support and more utilization of proxies, such as the SIP proxy.