ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006

International Telecommunication UnionITU-T

IMS based NGN IMS based NGN ArchitectureArchitecture

and its application and its application

Dick KnightBT Group plc

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 2

ITU-TOutline

o IP Multimedia Subsystem• Overview & Key Features• Use in NGN• Benefits

o Support for PSTN/ISDN Replacement• Simulation• Emulation

o Overall Architecture• ITU-T SG13, ETSI TISPAN & BT 21CN

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 3

ITU-TIP Multimedia Subsystem

o SIP-based control system to enable media-agnostic service delivery in IP networks• Secure registration• Secure communications• Location independence• Separation from Service providing application• Specified by 3GPP

o Control system for a flexible service delivery platform

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 4

ITU-T

Key Elements

UE P-CSCF S-CSCF

ASHSS

Transport Network

NACF & RACF

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 5

ITU-T

Key Elements Functionality 1

o UE – User Equipmento P-CSCF

• Proxy Call Session Control Function

• First contact point• Forward SIP messages

from UE to S-CSCF and vice-versa

• Generation of CDRs.• Maintain security

association to UE• Authorisation of

bearer resources

o HSS Home Subscriber Server• Mobility Management• User security• Service Provisioning &

authorisation support• Call / Session

establishment support• GUP Data Repository• Identification handling• Access authorisation• Application Services

Support

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 6

ITU-T

Key Elements Functionality 2

o S-CSCF• Serving Call Session

Control Function• Control for registered

UE sessions• May behave as Proxy

Server or User Agent• Interaction with

Services Platforms• Provide endpoints

with service event related information

• Obtain Address of entry point for network serving the destination user

• Modify the SIP request according to HSS and service control interactions

• Perform preference and capability matching

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 7

ITU-TIMS in NGN

o Performs Service Control Functions• Within the service stratum• Meets the requirements of Y.2001

o Flexible approach to services• Service delivery using Internet applications,

services and protocols

o Provides inherent mobility supporto Already exists!o BUT – specific to IP Connectivity Access

networks

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 8

ITU-T

RACFNACF

IMS Adaptations in NGN

Specific adaptations to NGN – generic access

IMSUE

Transport Network

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 9

ITU-T

IMS Adapted to NGN

o Control of IP Transport Networks (admission control, QoS, authentication, etc.)

o Co-ordination of multiple control components to a single core transport

o Interworking and interoperability with legacy and other networks

o Mutual de-coupling of applications from session/call control and transport

o Access technology independence of session/call control and applications

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 10

ITU-T

Architecture of IMS for NGN

Figure 1 of draft ITU-T Recommendation Y.IFA

MGW

MGCF CSCF

BGCF

CSCF BGCF

SLF

P-CSCF

MRFP

MRCF

Mk

Mi

Mw

Dx

Cx

Mr

Mg

Mw

Mj

PSTN

Mn

Mp

Mm

Mb Gq Gm

Sh

Dh

ISC

HSS

Other IP Multimedia Networks

PSTN

IP Connectivity Access Network

Mb

UE

AS

Mb

Mb

(AAA+DB)

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 11

ITU-T

PSTN/ISDN Replacement

Simulationo Interactions between

AS and UE provide “PSTN/ISDN-like” services to NGN Users

o IP “Terminals”o Includes terminal

adapterso Network and UE based

services

o Example use of IMS

Emulationo PSTN/ISDN service

capabilities and interfaces using adaptation to an IP infrastructure

o Legacy user equipment and interfaces unchanged

o Two approaches:• Call Server

(Softswitch)• IMS-based

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 12

ITU-T

S-CSCF

AS(ISUP-aware)

HSS

AGCFH.248

IMS-Based Emulation

Transport Network

NACF & RACFPSTN ISDN UE

Access Media G/W

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 13

ITU-TAdvantages of IMS PES

o Preserves common interface to RACS & transport network

o Common service control functionso Common Routing and configuration data

between emulated PSTN/ISDN Users and NGN Users

o Economy of scale• Consider effects of reducing numbers of

emulated users• Provision of advanced services

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 14

ITU-T

Service Control Architecture

ANIApplication

Application Support Functions &Service Support Functions(may include own Authentication, Authorization and Accounting)

ANIApplications

Application Support Functions & Service Support Functions(may include own Authentication, Authorization and Accounting)

other IP MMNetwork

(e.g. IMS)

PSTN/ISDN

Internet

Other NGN

Access Packet Transport Functions

NACF

End-User Functions

Core Packet Transport Function

RACFNGN UNI

Subscription

User Authentication

& authorisation

UserSignalling I/W

Media Res. Broker

Media G/WControl

Subscription

User

SubscriptionLocator

User Profile Network Sig.Interworking

MultimediaService FE

I/C BorderG/W Control

I-CSCF

S-CSCF Breakout

G/W Control

Media ResourceControl

P-CSCF

AccessGatewayFunction

Based on Y.FRA Fig. 3

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 15

ITU-T

ETSI TISPAN Architecture(* apart from IMS-based PSTN Emulation)

Other IP N

etworks

IP Transport (Access and Core)I-BGF

UPSF

P-CSCF

I/S-CSCF

BGCF

SLF

ChargingFunctions

IWF

PSTN Emulation (R2)

Mw

Mw/Mk/Mm

MrMg

Mj

Mi

Mp Mn

GmGq'

ISCCx Dx

DhSh

Ic

Rf/Ro

Rf/Ro

IbIw

Gq'

PSTN/ISD

N

SGFMRFC MGCF

MRFP

e4

Ie

MwIBCF

MkMk

Application ServersRf/Ro

AGCF

e2

P1

P2

P3

UE

CNG

MG

IMS /PSTN Simulation

Gq'

SPDF

A-RACF

Resource & AdmissionControl

RACS

SPDFNetwork

AttachmentSubsystem

Re Ia

RCEF BGF

UtUt

T-MGF

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006 16

ITU-T

BT 21CN Architecture

H248

POTs

OSA ASCall Application

Servers

SIP Application Server

AS AS AS

SIP Stack

SIP Application Servers

OSA AS

AE

OSA SCS

MRFC MGCF

HSSplus ISC

Mr

Mp

Mg

Mn

P- CSCF

I-CSCF

Gq’Gm

Mw

Sh

S-CSCFMw

SCIMISC

Ia

IMS

RqSPDF

ReSGF

Cx

BCF

SPDFMw

P2

Presence

Messaging

Other TDMNetworks

3rd PartyApplications& Services

Other IPNetworks

ExternalApplication

s

IAD

MediaServer

MPLS/IPNetwork

MediaGateway

BorderGatewayWiMax/WLAN

PSTN

BRASBorder

GatewayBackhaul

MSAN

OtherIMS

C7

SBR(ENUM)

PSTNCall ServerCAC

BWM

A-RACF

Metro and CoreMSAN and Access

Service Assembly

AGCF

SIP

e4e2

e1

ITU-T Workshop “NGN and its Transport Networks“Kobe, 20-21 April 2006

International Telecommunication UnionITU-T

Thank YouThank You