Post on 02-Feb-2016
© Vodafone Group 2004
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C2 COMPANY CONFIDENTIAL
Evolución de IMS y la Red de Nueva Generación
José Carlos Sendra Alcina. Group R&D VodafoneMáster Vodafone-UPM. Madrid 2009
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© Vodafone Group 2007 April 22, 2023
Contenidos
1. Arquitectura de Referencia de IMS
2. Policy Control and Charging (PCC)
3. Voice Call Continuity (VCC)
4. CS bearers in IMS (CSI)
5. SMS over IP
6. Llamadas de emergencia
7. GRUU
8. IMS Communication Service Identifier
9. Telefonía Multimedia
10.IMS como una Transit Network
11.Optimizaciones a IMS
12.NGN
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© Vodafone Group 2007 April 22, 2023
IMS
UTRAN
SGSN GGSNUE
PS Domain
Arquitectura IMS
I-CSCF
Go Gi
I-CSCF
P-CSCFS-CSCF
Mw
HSS
Cx
Cx
Other IP/IMS network
Mm
CSCFs are the IMS entities responsible of the call control: there are 3 types of CSCFs depending on their role:•P-CSCF (Proxy CSCF)•S-CSCF (Serving CSCF)•I-CSCF (Interrogating CSCF)
The PS domain provides the IP bearer to access to the IMS, i.e. a PDP
context.
The HSS holds the IMS service profile of the subscribers.
S-CSCF interconnects to external IP networks and other IMS networks.If THIG is used by the operator to hide its internal configuration, the connection to external networks goes through an I-CSCF.
Gi
Traffic Plane
Control Plane
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© Vodafone Group 2007 April 22, 2023
IMS
UTRAN
SGSN GGSNUE
PS Domain
Arquitectura IMS
I-CSCF
Go Gi
I-CSCF
P-CSCFS-CSCF
Mw
HSS
Cx
Cx
Other IP/IMS network
Mm
SGWMGCF
BGCF
IMS-MGW
Legacy/PSTN
Mk
Mi
Mg
Mj
MnGi
MRF
Gi
Mr
Go
GqThose entities
are responsible for interworking
between IMS and CS
domain/PSTN
In Release 6, the PDF can be separated from the P-CSCF. Those two entities are then connected through the Gq interface.
The MRF is used for
multiparty call control
Traffic Plane
Control Plane
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© Vodafone Group 2007 April 22, 2023
IMS
Arquitectura IMS
UTRAN
SGSN GGSNUE
PS Domain
I-CSCF
I-CSCF
P-CSCFS-CSCF
HSS
Other IP/IMS network
SGWMGCF
BGCF
IMS-MGW
Legacy/PSTN
MRF
Traffic Plane
Control Plane
Rf
CCF
CGF
Ga
For offline Charging, CCF and CGF are responsible for
collecting charging information from PS domain and IMS
entities.
Gz
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© Vodafone Group 2007 April 22, 2023
IMS
Arquitectura IMS
UTRAN
SGSN GGSNUE
PS Domain
I-CSCF
I-CSCF
P-CSCFS-CSCF
HSS
Other IP/IMS network
SGWMGCF
BGCF
IMS-MGW
Legacy/PSTN
MRF
Traffic Plane
Control Plane
ISCSCF
ECF Ro
OnlineChargingSystem Gy
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© Vodafone Group 2007 April 22, 2023
Policy Control and Charging (PCC)
_ Description
• PCC provides the functionality to identify service flows (which in IMS is equivalent to the user data part of an IMS session) through packet analysis and apply the following at the bearer/access level:
– Flow Based Charging, including charging control and online credit control;
– Policy control (e.g. gating control, QoS control, etc.).
• Defined in 3GPP TS 23.203
_ IMS Nodes Affected:
• P-CSCF
• AS (depending on service configuration)
_ New Interfaces required at the nodes affected:
• Rx (defined in 3GPP TS 29.214) – Diameter Rx application
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© Vodafone Group 2007 April 22, 2023
Policy Control and Charging (PCC)
P-CSCF(PCC AF)
AS(PCC AF)
S-CSCF
PCRF
PCEF (e.g. GGSN)
SIP UA
End Device
Rx
Rx
Gx
Gm
Bearer 1 (e.g. PDP context)
Bearer 3 (e.g. PDP context)
Bearer 2 (e.g. PDP context)
Packet Filter
Packet Filter
Packet Filter
Packet Filter
Packet Filter
Flow level charging and QoS enforcement performed as part of
filtering process
Provide service information
Provide filtering information (including authorised QoS and charging information)
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© Vodafone Group 2007 April 22, 2023
UE
5555::aaa:bbb:ccc:ddd v=0 o=- 2987933615 2987933615 IN IP6 5555::aaa:bbb:ccc:ddd s=- i=videoconference_vodafone c=IN IP6 5555::aaa:bbb:ccc:ddd t=907165275 0 m=video 3400 RTP/AVP 98 b=AS:35 a=curr:qos local none a=curr:qos remote none a=des:qos mandatory local sendrecv a=des:qos none remote sendrecv a=rtpmap:98 H263 a=fmtp:98 profile-level-id=0
v=0 o=- 1073055600 1073055602 IN IP6 5555::eee:fff:aaa:bbb s=- c=IN IP6 5555::eee:fff:aaa:bbb i=videoconference_vodafone t=907165275 0 a=group:SRF 1 2 m=video 6400 RTP/AVP 98 b=AS:35 a=mid:1 a=curr:qos local none a=curr:qos remote none a=des:qos mandatory local sendrecv a=des:qos none remote sendrecv a=conf:qos remote sendrecv a=rtpmap:98 H263 a=fmtp:98 profile-level-id=0
SDP offer
SDP answer
Charging rule example
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Voice Call Continuity (VCC)
_ Description
VCC provides the capability to transfer the path of a voice call between a CS system (GSM/UMTS) and IMS, and vice versa.
Defined in 3GPP TS 23.206
_ IMS Nodes Affected:
• New AS(s) to perform VCC functions (CSAF – CS Adaptation Function, DTF – Domain Transfer Function, DSF – Domain Selection Function)
_ New Interfaces required at the nodes affected:
• CSAF to CAMEL service (not-specified in 3GPP)
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© Vodafone Group 2007 April 22, 2023
Voice Call Continuity (VCC)
VCC Application
VMSC
MGCF S-CSCF
Domain Transfer Function
CS Adaptation Function
CAMEL Service
P-CSCF
VCC UE
MwI-CSCF Cx
DomainSelection Function
gsmSCF
PLMN/PSTN
IP Multimedia NetworksCAP
A/Iu Gm
HSS
Sh
Sh
Mg Mw
PLMN/PSTN
PLMN/PSTN
Unspecified interface
GMSC
ISUP
V3
ISUP
MaMa ISC ISC ISC
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© Vodafone Group 2007 April 22, 2023
Voice Call Continuity (VCC)
CS Domain
IMS Core
VCC Application / DTF
Voice user on VCC capable
device
Remote Party
MGW
VC
C D
om
ain
T
ran
sfe
r
Voice media path
Signalling path
IP Gateway (e.g. GGSN)
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CS Bearers in IMS (CSI)
_ Description
CSI caters for the basic principle where real time media may not be optimally carried on an IP access and as a result separate sessions / calls may be presented. CSI consists of 2 basic steps in relation to the presentation to the endpoints:
1) No interworking between CSI capable and incapable devices – Provides a capability exchange mechanism to allow endpoints of an existing call to determine whether a CS call and IMS session can be established in parallel. Endpoints are responsible for presenting a single session to user.
2) Interworking between CSI capable and IMS only devices – Core network provides a mechanism to identify related calls / session (in CSI origination scenarios) and merge into a single session. Splits media as necessary in CSI termination.
Defined in 3GPP TS 23.206
_ IMS Nodes Affected:
• CSI-AS (new AS)
• MGCF
_ New Interfaces required at the nodes affected:
• None
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© Vodafone Group 2007 April 22, 2023
CS Bearers in IMS (CSI)
CS
IMS
xRAN
CS domain
1
PS domain
1
PS domain
2
IMS domain
2IMS domain1
xRAN UE 2UE 1 CSI AS
Gm
Uu/Um
Mw GmIMS
CSI termination
IMS session (for other media)
CS call (for voice)
Multimedia IMS session (for voice and other media)
IMS origination
Interworking between IMS only endpoint and CSI endpoint
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SMS over IP
_ Description
SMS over IP provides the transport level interworking of the Short Message Service between the UE and Core Network and between existing DTAP & MAP transport and IP based transport.
Defined in 3GPP TS 23.204
_ IMS Nodes Affected:
• HLR / HSS
• New AS (IP-SM-GW)
_ New Interfaces required at the nodes affected:
• Support MAP interface at the AS / IP-SM-GW to handle SM transfer and routeing queries
• Support MAP interface at the HSS if one is not already present for routeing queries
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© Vodafone Group 2007 April 22, 2023
IMS Core
SMS over IP
IP-SM-GWUE
HSS
SMS-SC
SIP MESSAGE
Message Body:SM-RL information
(e.g. SMS-SC address) +
SM-TL PDU (as per 3GPP TS 23.040)
SM-TL PDU(as per 3GPP TS 23.040)
MAP signalling
Note: The structure, format and contents of the message body of the SIP MESSAGE are still to be agreed in 3GPP
SM-RL data
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IMS Emergency Calls
_ Possible to place emergency calls in the IMS domain
_ Aligns as much as possible with IETF solution from the ECRIT working group (Emergency Context Resolution with Internet Technologies )
_ Fixed broadband specification 80% complete, GPRS not yet specified
_ Voice is currently the only media specified, others (e.g. real-time text) are future work
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© Vodafone Group 2007 April 22, 2023
IMS Emergency Calls
_ Emergency call architecture
Ml
to PSAP (via PSTNvia BGCF/
MGCF)
to PSAP or ECS via IP mutimedia
Network
UE P-CSCF E-CSCFGm Mw
Mi/Mg
Mm
S-CSCFMm/Mw
Mw
from PSAP
Le (e.g. E2)
from PSAPLRF
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© Vodafone Group 2007 April 22, 2023
IMS Emergency Calls
_ Introduces Emergency CSCF entity
_ Emergency numbers can be downloaded to the UE
_ UE detects that an emergency call is required and includes the emergency service URN (urn:service:sos:*)
_ P-CSCF responsible for detecting emergency calls
_ Location retrieval function used by the Emergency CSCF to find the Public Safety Answering Point (PSAP)
_ User can be called-back via the S-CSCF in their home network
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GRUU
_ Globally Routable User Agent URI
_ GRUU is the property of global routability
_ A GRUU is a SIP URI that routes to a specific single device
_ Original intention of SIP was that the Request URI has the GRUU property, but not realised because
• A contact address is often only routable from within a user’s home network
• Multiple IMS devices can have the same public user identity
_ GRUU property required for call transfer and conference calls
_ GRUU adopted by 3GPP, some privacy issues remain to be solved
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© Vodafone Group 2007 April 22, 2023
GRUU (Globally Routable UA URI)
_ Description
_ - URI used by anyone to route a call to a specific device
_ - Registrars keep track of individual device over registration procedure by means of Instance Identifier
_ - Two types of GRUU: temporary GRUU and public GRUU
_ - Stemmed from IETF and specified as a Release 7 feature in 3GPP TS 23.228 and TS 24.229
Dave’s Devicein the UK
Dave’s Device in the US
1. REGISTERContact: <sip:dave@xxx.x.x.x>;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0-a765 00a0c91e6bf6
3. REGISTERContact: <sip:dave@yyy.yy.yy.y>;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6
2. 200 OKContact: <sip:dave@xxx.x.x.x> ;pub-gruu="sip:dave@vodafone.com ;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6" ;temp-gruu="sip:uk8a788@vodafone.com;gr" ;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0-a765 00a0c91e6bf6>"
4. 200 OKContact: <sip:dave@yyy.yy.yy.y> ;pub-gruu="sip:dave@vodafone.com ;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6" ;temp gruu="sip:usa355@vodafone.com;gr" ;+sip.instance="<urn:uuid:f81d4fae-7dec-11d0- a765-00a0c91e6bf6>"
Vodafone’s Registrar
Move to
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IMS Communication Service Identifier
_ Label to help identify that a session belongs to a service
_ Two parts, a service identifier (+g.ims.icsi.xxxxxx ) and an application identifier (+g.ims.iari.yyyyyy )
_ Service identifier indicates general network-based functions available to the session (e.g. supplementary services)
_ Application identifier helps routing to an application in the network or within a terminal
_ Terminal can register identifiers to indicate its service capabilities to the network
_ Identifier can be used by a terminating network or a transit network to provide network-based services
_ Current proposal is based on the feature-tag specified in RFC 3840 and RFC 3841
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Multimedia Telephony
_ Service supported by IMS that has requirements defined by the 3GPP requirements working group (SA1)
_ Media include voice, video, real-time text, and file sharing
_ Supplementary services are optionally available, including call diversion and call hold
_ Specification of supplementary services currently refers to TISPAN specifications
_ Joint meeting between 3GPP and TISPAN on November 27th and 28th to discuss supplementary services
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IMS as a Transit Network
_ 3GPP recognises that IMS might be used in transit scenarios
_ IMS operator providing transit functionality for its own, non-IMS (CS domain), customers:
• the operator is serving its own customers, some of which have been migrated to IMS while others are still CS Domain subscribers
_ IMS operator providing transit functionality to enterprise networks
• Operator serving as a transit network for an enterprise IP network and provides connectivity to both PSTN and IP endpoints
_ IMS operator providing transit functionality to other network operators
• Operator serving as an IMS session based routing backbone for a PSTN operator or another IP network
• Provides connectivity to both PSTN and IP endpoints (PSTN <‑> PSTN, IP <‑> IP, PSTN <‑> IP)
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IMS as a Transit Network
Terminating IMS network with transit support
Originating Network
MGCF
Transit Functions
Terminating IMS Network
I-CSCF
CS Domain
Other IMS Entities
ISUP
SIP SIP
SIP
SIP
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¿Qué significan las siglas NGN?
_ ¿unas “siglas de moda” para vender revistas técnicas o participar en conferencias de telecos?...
_ ¿una nueva tecnología revolucionando la comunicación humana?...
_ …la Red de Nueva Generación (NGN)???
_ Wikipedia – Definición de la ITU-T
“Una Red de Nueva Generación (NGN) es una red de paquetes capaz de proporcionar servicios, incluyendo Servicios de Telecomunicación, y capaz de usar multiples redes de banda ancha, tecnologías de transporte con Calidad de Servicio y en la cual las funciones relacionadas con el servicio son independientes de las tecnologías de transporte que las soportan. Ofrece a los usuarios acceso no restringido a diferentes proveedores de servicio. Soporta movilidad en general, lo cual posibilita prestar servicios a los usuarios de forma consistente y en cualquier lugar.”
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O sea, que eso es..
_ Idea General detrás de la NGN• Una única red transporta toda la
información y los servicios (voz, datos y toda clase de media, como video, audio, etc.)
• Dicha Red está basada en el Internet Protocol (IP)
• El trabajo de estandarización está siendo liderado en ETSI, más específicament bajo TISPAN
• El proyecto TISPAN NGN se ha implementado en dos fases correspondientes a NGN Release 1 y Release 2
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© Vodafone Group 2007 April 22, 2023
¿Para qué evolucionar?
UMTS
IP Core
AccessAccess
Access
GSM/EDGE
WiFi/WiMax
xDSLPSTN / ISDN
Broadcast
Content and Services
Servers ...
Services Services Services
PL
MN
PS
TN
/ IS
DN
Da
ta /
IP
CA
TV
Services
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© Vodafone Group 2007 April 22, 2023
Relación TISPAN – 3GPP
_ TISPAN Rel-1 escalas de tiempo y dependencias están alineadas con 3GPP Release 7.
• TISPAN NGN Rel-1 definición completada en Dic 2005
• TISPAN NGN Rel-1 correcciones hasta Mayo 2007
• 3GPP Rel-7 estará completada en Marzo 2007
_ TISPAN Rel-2 escalas de tiempo y dependencias están siendo alineadas con el trabajo del 3GPP Release 8 en FMC.
• TISPAN NGN Rel-2 definición completada para final de 2006
• 3GPP congelará los requisitos para Rel-8 requirements al final de 2007
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Objetivos Generales de la NGN Release 1
_ NGN Rel-1 fue completada en TISPAN#9 (Dic. 2005)
_ Proporciona el primer conjunto de especificaciones NGN implementables.
_ Principales objetivos
• Sustitución de PSTN/ISDN (proporcionando soporte a los teléfonos existentes)
• Introducción de servicios multimedia en redes de banda ancha fijas (o servicios IMS)
_ Proporciona la arquitectura general de la RNG
_ Define los subsistemas y cómo estos interactúan:– 3GPP Rel-7 IMS re-uso y su relación con otros componentes de la
TISPAN RGN. Las modificaciones a IMS son responsabilidad de 3GPP. – Define PSTN/ISDN Emulation Subsystem (PES)– Define PSTN/ISDN Simulation Services (PSS)– Network Attachment Subsystem (NASS)– Resource and Admission Control Subsystem (RACS)
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Capacidades de Servicio principales en NGN Release1
_ Establecimiento de sesión y control para servicios basados en sesión
• Servicios conversacionales en tiempo real (voz, mensajería, etc.)
• Telefonía multimedia
• Videotelefonía
_ Presencia
_ Escenarios de migración PSTN/ISDN para ambos esquemas de sustitución (emulación) y evolución (simulación)..
_ Otros servicios, como Streaming
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Arquitectura TISPAN NGN Release 1NASS: Network Attachment SubSystemRACS: Resource and Admission Control Subsystem
Capa de transporte
Capa de servicio
Funciones de transferencia
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Control de la conectividad IP.
_ La conectividad IP la proporcionan dos subsistemas de control que realizan unas tareas similares al GPRS en 3GPP. Estos sistemas ocultan los detalles de la tecnología usada en las redes de acceso y de transporte core, por debajo del nivel IP.
_ Network Attachment Sub-System:• Provisión de la dirección IP al usuario (e.g. DHCP).• Autenticación del usuario a nivel de acceso.• Autorización de acceso.• Configuración del acceso.• Gestión de la localización.
_ Resource and Admission Control Sub-System:• Control de admisión• Reserva de recursos.• Control de Policy.• NAT traversal.
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Arquitectura del NASS.
UE
CN
GC
us
tum
er
Ne
two
rk
Ga
tew
ay
TE
UAAFUser Access Authorization
Function
ARFAccess Relay Function
CNGCFCNG Configuration
Function
RACSCLF
Connectivity Session Location and Repository
Function
AMFAccess Management Function
e3
e1
NACFNetwork Access
Configuration Function
a1
e1
a3
a2 a4
PDBFProfile Data Base
Function
e5
e2
Service Controlsubsystem
e2
e4
•IP address allocation•Provide access network ID
•IP address RQ NACF•Authentication RQ UAAF•For PPP, is a Radius client UAAF (Radius Server)
•Register IP-Network association•Responds to location queries form Service Control Subsystem
•User authentication•Authorization checking
•User authentication data repository
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Arquitectura del NASS. Información en el CLF
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Ejemplo de un acceso PPP. Arquitectura
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Ejemplo de un acceso PPP
1. UE/CNG initiates a PPP request to apply for an IP address. PPP is used for Access and Line authentication.
2. AMF relays translates PPP request to an Access request to the UAAF.
3. AMF sends the configuration request to NACF to obtain IP address and other parameters including the IP
address of a TISPAN NGN Service/Applications Subsystems (e.g. P-CSCF).
4. NACF sends to the CLF the binding information of allocated IP address, Line ID and IP edge ID. The CLF
pushes the binding information to the RACS via the e4 interface.
5. AMF sends the IP address of a TISPAN NGN Service/Applications Subsystems (e.g. P-CSCF) to UE/CNG
within PPP IPCP configuration option extension.
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Transport LayerTransport Layer
Core Border NodeCore Border NodeIP edgeIP edge
RACSRACS
Arquitectura del RACS.
UE
L2TP
RCEFResource Control
Enforcement Function
NASS
A-RACFAccess-Resource and
Admission Control Function
BGFBorder GW Function
Re
Rq
AFApplication Function
Gq’
e4
SPDFService Policy Decision
Function
Ia
Di
Access NodeAccess Node
Ds
Ra
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Ejemplo. Petición de recursos.
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Interacciones con PSTN/ISDN
Desafío – Mantener los servicios tradicionales (legacy) sobre NGN
Usuarios IP
Usuarios PSTN
?_ Emulación de PSTN/ISDN
• “Proporciona capacidades de servicio del tipo PSTN/ISDN usando control de sesión sobre interfaces e infraestructura IP"
• Sustituye una red PSTN/ISDN desde el punto de vista de los terminales tradicionales (legacy). Requiere un subsystema específico, el PSTN/ISDN Emulation Subsystem.
_ Simulación de PSTN/ISDN • " Proporciona capacidades de servicio e interfaces PSTN/ISDN usando
adaptación a una infraestructura IP"• Proporciona servicios tipo PSTN/ISDN a terminales avanzados (teléfonos IP) o
interfaces IP.
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Subsistema de Emulación de PSTN/ISDN
_ Proporciona servicios PSTN/ISDN a terminales tradicionales usando adaptación a una infraestructura IP.Especialmente concebido para facilitar el reemplazo de infraestructura TDM, sin afectar a los terminales tradicionales.
_ Utiliza los mismos interfaces que IMS, es decir, transporte NGN, NASS y RACS, pero no está basado en IMS
_ Existen Gateways que convierten interfaces tradicionales, como los analógicos PSTN Z, a interfaces NGN.
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…y por fin, IMS (IP Multimedia Subsystem)
_ En la Arquitectura NGN, IMS asume el papel de elemento central de Red (Core IMS).
_ El Core IMS de la arquitectura NGN Release 1 coincide en gran medida con el 3GPP IMS definido en la Release 6-7.
_ Pero, no es exactamente el mismo IMS. Aquí debe soportar accesos fijos, especialmente xDSL.
_ Y recordar, ¡¡IMS es una red de señalización, en 3GPP o en NGN!!
IMS
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Diferencias que impactan en la especificación del Core IMS
• Wireline versus Wireless: Las restricciones en términos de escasez de ancho de banda, seguridad y retardos de transmisión son diferentes.
• Terminales: Se prevee que los terminales NGN tengan requisitos menos estrictos, por ejemplo, en cuanto a soporte de IPv6, disponibilidad de USIM/ISIM, etc.
• Información de localización : La información de localización es de naturaleza distinta en ambos entornos y habitualmente no estará disponible en el UE.
• Gestión de los recursos: No existe una señalización específica de reserva de recursos en los terminals y puntos de acceso a la red, es más, no existe un canal dedicado para señalización.
• Regulación: Diferentes contextos que conducen a diferentes restricciones.
• Terminales vs Usuarios: Los usuarios no están siempre ligados a los terminales.
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Core IMS y su entorno
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Arquitectura del Core IMSO
ther IP
Netw
orks
IP Transport (Access and Core)
T-MGF
I-BGF
AS HSS
IBCF
A-BGF
P-CSCF
S-CSCF
BGCF
I-CSCFSLF
ChargingFunctions
IWF
UE
«Core IMS »
Mw
Mw Mw/Mk/Mm
Mr
Mg
Mj
Mi
Mp MnGm
Gq
ISC Cx
Dx
Dh
Sh
Ic
Rf/Ro
Rf/RoCxIb
Ia
Id
PS
TN
/ISD
N
SGFMRFC MGCF
MRFP
Resource and Admission Control Subsystem
Network Attachment Subsystem
If
Ie
Mi
Mw
Oth
er IP N
etwo
rks
IP Transport (Access and Core)
T-MGF
I-BGF
AS HSS
IBCF
A-BGF
P-CSCF
S-CSCF
BGCF
I-CSCFSLF
ChargingFunctions
IWF
UE
«Core IMS»
Mw
Mw Mw/Mk/Mm
Mr
Mg
Mj
Mi
Mp MnGm
Gq
ISC Cx
Dx
Dh
Sh
Ic
Rf/Ro
Rf/RoCxIb
Ia
Id
PS
TN
/ISD
N
SGFMRFC MGCF
MRFP
Resource and Admission Control Subsystem
Network Attachment Subsystem
If
Ie
Mi
Mw
SIP
DIAMETER
H.248
impacted
NGNspecific
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© Vodafone Group 2007 April 22, 2023
Arquitectura del Core IMS. Nodos específicos.
• Interconnection Border Control Function (IBCF) e Interworking Function (IWF): Estos elementos de la arquitectura son responsables de manejar la interconexión hacia otras redes IP.
• Signalling Gateway Function: Realiza la conversión de la señalización, en los dos sentidos, entre transporte de la señalización basado en SS7 e IP.
• Interconnection Border Gateway Function (I-BGF): Proporciona el interfaz entre dos dominios IP, a nivel de la capa de transporte. Incorpora funcionalidades como filtrado de paquetes (gate), NAPT, IPv4-IPv6 interworking, marcado de paquetes, etc.
• P-CSCF: No es un nodo específico de NGN, pero se ve afectado por los nuevos accesos definidos, basicamente en dos aspectos:– Incorpora funcionalidad ALG, requerida para interactuar con la NAPT localizada en el plano de transporte, vía el RACS.– Necesita interactuar con el NASS para conseguir información relacionada con la conectividad IP del cliente (p.e. conseguir
datos de la localización física del usuario). • UE: No dispone de ISIM/USIM, por lo que los parámetros necesarios para el registro en IMS deben estar preconfigurados
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© Vodafone Group 2007 April 22, 2023
Ejemplo. xDSL origina llamada (I)
P-CSCF1 SPDF I-BGFI-BGF S-CSCF
1.INVITE(SDP offer) 2. AAR Request
3. Reserve IMS Connection
4.Reserve Connection
A-RACF
5. Reserve IMS Connection ACK
7. INVITE (SDP offer)
10.Offer Response
UE
6. AAR Answer
8. Service Control
9.INVITE(SDP offer)
11. Offer Response
12. AAR Request13. Admission Request
14. Resource Admission
15. Admission Response
16. Configure IMS Connection
17. Configure Connection
18. Configure IMS 20. Offer Response 19. AAR Answer
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© Vodafone Group 2007 April 22, 2023
Ejemplo. xDSL origina llamada (II)
P-CSCF1 SPDF I-BGFI-BGF S-CSCF
21. UPDATE(Opt SDP)
A-RACF
22. UPDATE (Opt SDP)
24. UPDATE OK
UE
23. UPDATE(Opt SDP)
37. AAR Answer
34. Open Gates
35. Open Gates
36. Open Gates Response
41. ACK
38. 200 OK
25. UPDATE OK26. UPD. OK 27. Ringing
28. Ringing29. Ringing 30. 200 OK
31. 200 OK
32. AAR-Request
33. Approval of QoS Commit
39. Start media
40. ACK
42. ACK
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© Vodafone Group 2007 April 22, 2023
José Carlos Sendra Alcina
Vodafone R&D-ES
Isabel Colbrand, 22
28050-Madrid
+34 610513503
Jose-carlos.sendra@vodafone.com
www.vodafone-rnd.com