International Telecommunication Union
ITU-T
PSTN/ISDN Emulation
Architecture
Dr. Ghassem Koleyni
Nortel Networks
Tel: +1 613 763 4154
Fax: +1 613 765 6295
ghassem@nortel.com
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
Content
ITU-T
o
o
o
o
o
o
Definition
Transport and service configuration
Functional architecture
CS-based functional architecture
IMS-based functional architecure
Conclusion
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
2
Transport & service configuration for NGN
ITU-T
Applications
Service Stratum
Application Support
Functions and
Service Support Functions
Application
Functions
S. User
Profile
Functions
Other Multimedia Service
Components …
Service
Control
Functions
Streaming Service
Component
IP Multimedia
Component
IP Multimedia
&PSTN/ISDN
Simulation
Service Component
GW
Legacy
Terminals
Legacy
Terminals
Customer
Networks
NGN
Terminals
End-User
Functions
GW
T.User
User
Profile
Profile
Functions
Functions
Network
Attachment
Network
Access
Control Functions
Attachment
Functions
(NACF)
NAAF
Access
Network
Access Transport
Functions
Functions
Resource and Admission
Control Functions
(RACF)
Edge
Functions
Other Networks
PSTN / ISDN Emulation
Service Component
Core
Core Transport
transport
Functions
Functions
Transport Stratum
* Note: Gateway (GW) may exist in either Transport Stratum
or End-User Functions.
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
3
NGN functional architecture
Applications
ANI
Application
Application Support Functions & Service Support Functions
(may include own Authentication, Authorization and Accounting)
S-5: S. User
Profile FE
S-14: Media Resource
Broker FE
S-4: Subscription
Locator FE
S-10: Breakout
Gateway Control FE
T-13:
T. Location
management
FE
T-8:
Media
Resource
Processing
FE
T-4: Access
Relay FE
Legacy
Terminal
T-1: Access
Media
Gateway
FE
T-3: Edge
Node FE
Access Packet Transport Functions
T-5:
Access
Border
Gateway
FE
Core Packet Transport Functions
ITU-T Workshop on Scope
“Next
Generation Networks“
of NGN
Hanoi, Vietnam, 15-16 May 2006
T-9:
Signalling
Gateway
FE
T-6:
Interconnection
Border
Gateway FE
T-7:
Trunk
Media
Gateway
FE
Core Transport
RGW
NGN
Terminal
other IP MM
Network
(e.g. IMS)
T-16 Core Transport
Resource Control FE
T-15: Access Transport
Resource Control FE
Legacy
Terminal
T-2: Access
Node FE
S-9: Media GW
Control FE
T-14: Policy Decision FE
T-10:
T. Network Access Control FE
Customer
Network
Other NGN
RACF
T-11:
T. Authentication
&Authorization
FE
NGN
S-7: Interconnection
Border Gateway
Control FE
S-13: Media Resource
Control FE
T-12: T. User
Profile FE
End-User UNI
Function
S-3: Interrogating Call
Session Control FE
S-1: Serving Call Session Control FE
S-8: Access GW
Control FE
NACF
S-12: Network Signaling
Interworking FE
S-15:Multimedia
Service FE
S-2: Proxy Call Session
Control FE
S-11: User Signaling
Interworking FE
S-6: S. Authentication
& Authorization FE
Service Control
Management functions
ITU-T
Internet
PSTN/ISDN
4
PSTN/ISDN Emulation
ITU-T
Provision of PSTN/ISDN service
capabilities and interfaces using
adaptation to an IP
infrastructure.
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
5
Functional Architecture of PSTN/ISDN
emulation
ITU-T
o Two different architectures
• CS-based
• IMS-based
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
6
ITU-T
Functional Architecture of CS-based
PSTN/ISDN emulation
APL-GW-FE
I12
I9
I10
I10
Network Border
AS-FE
(may include own Authentication, Authorization and Accounting)
Other IP MM
eg:IMS
I15
I9
SPF
SSF
I14
I11
SUP-FE
CCF
IBC-FE
SIF
Other PES
RF
AGCF
MRCF
MGCF
I8
I5
RACF
I1
I3
I4
MRP-FE
I2 ABG-FE
Legacy
teminal
AMG-FE
Packet Transport
Functions
I6
I7
IBG-FE
SG-FE
I13
PSTN/ISDN
TMG-FE
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
7
CS-based PES functional entities - 1
ITU-T
o Call Control Function (CCF)
• provides two party and multi-party call control function
• Provides trigger mechanisms to access IN functionality (e.g.
passes events to the SSF)
o Access Gateway Control Function (AGCF)
• Controls one or more AMG-FEs to access PSTN or ISDN users
• Is in charge of the registration, authentication to AMG-FE
• Recognizes the main events such as off-hook, dialling of digits,
end of dialling and on-hook
• Can control AMG-FE to send signalling indications for voice
services to users, e.g. dial-up tone, ringing tone and ringing back
tone, busy tone, etc.
• It ensures the transparent data transport between ISDN user side
and IP side from the control level in media negotiation process
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
8
CS-based PES functional entities - 2
ITU-T
o Media Resource Control Function (MRCF)
• Controls MRP-FE and allocates resources which are
needed for services such as streaming, announcements,
and IVR (Interactive Voice Response) support
• Together with MRP-FE may also provide multi-party
conference bridges and media trans-coding.
o Media Gateway Control Function (MGCF)
• Controls the TMG-FE to inter-work with PSTN/ISDN.
• Allocates and releases resources of the TMG-FE, as well
as modifies of the usage of the resources
• In ISDN N*64Kbit/s unrestricted service scenario, it
ensures the transparent data transport between TDM side
and IP side from the control level in media negotiation
process
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
9
CS-based PES functional entities - 3
ITU-T
o Routing Function (RF)
• RF may be implemented as part of CS. If external to CS, it may
be shared between and accessed by different CSs
• Analyses user characteristics (such as called number, service
profile) and chooses the route to destination user.
• It may include routing policy function (such as routing depends
on average load sharing, routing depends on time, etc.) and
routing database
o Service provider function (SPF)
• It may provide the PSTN/ISDN supplementary services to user
also the services logic about PSTN/ISDN supplementary services
• Doesn’t provide the function about Application specific
authorization and authentication
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
10
CS-based PES functional entities - 4
ITU-T
o Service Switching Function (SSF）
）
• Enables access to IN service logic programs hosted in legacy
SCPs
• Interacts between the CCF and SCF
o Signalling Interworking Function (SIF)
• Provides protocol adaptation function and connection with
other NGN through IBC-FE
• If it interworking with IMS network it sends/receives SIP
message
• If it interworking with other Call Server based PES network, it
may send/receive SIP-I or BICC message
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
11
CS-based emulation reference points - 1
ITU-T
o I1: Reference point between AGCF and AMG-FE
• Allows flow of register and event messages such as telephone on-hook,
off-hook, and dial-up, etc. also messages for control of the resources of
AMG-FE
o I2: Reference point between AMG-FE and ABG-FE
• Allows flow of register and event messages such as telephone on-hook,
off-hook, and dial-up, etc. also transfer of control messages from AGCF
o I3: Reference point between ABG-FE and AGCF
• Allows transfer of messages such as register and event from AMG-FE and
those controlling the resources of AMG-FE
o I4: Reference point between the MRC-FE and MRP-FE
• The information flows at this reference point are used to carry the
message for controlling the media resource in MRCF
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
12
CS-based emulation reference points - 2
ITU-T
o I5: Reference point between the CCF and RACF
• Allows flow of messages to request the capacity to create, modify and
release resources for the media flow. When the call is set up, CCF will
request the RACF to create resources for the medial flow of the call. When
the call is released, CCF will be requested to withdraw the arranged
resource
o I6: Reference point between the MGCF and TMG-FE
• Allows flow of the register message and state notify message from TMG-FE
and control message from MGCF which are used to allocate the resource such
as trunk circuits, and codec resource
o I7: Reference point between the MGCF and SG-FE
• Allows flow of messages for call and supplementary services control to
facilitate CS-based PES interworking with PSTN
o I8: Reference point between the IBC-FE and IBG-FE
• Allows flow of messages to control the IBG-FE to facilitate media codec
ITU-T Workshop on “Next Generation Networks“
conversion function
Hanoi, Vietnam, 15-16 May 2006
13
CS-based emulation reference points - 3
ITU-T
o I9: Reference point between the SIF and APL-GW-FE
• Allows flow of information related to service request and response
o I10: Reference point between the SSF and APL-GW -FE
• Allows transmission or reception of call related information to AS-FE
o I11: Reference point between the SUP-FE and CCF
• Allows flow of user subscription information, such as user service characters
o I12: Reference point between the SUP-FE and AS-FE
• Allows flow of user or service information to AS-FE
o I13: Reference point between the SG-FE and PSTN/ISDN
• Allows flow of call control information for interworking with PSTN/ISDN
o I14: Reference point between the IBC-FE and other PES
• This is an NNI with other PES, and the information flows are used to carry
the call control information between PESs
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
14
ITU-T
Functional Architecture of IMS-based
PSTN/ISDN emulation
Application Servers
Ut1
UPSF
Rf/Ro
ISC
P1
Dh
Cx
Dx
IMS- PES Mw
Mw
AGCF
IBCF
Mg
MRFC
Gq'
MGCF
Ie
SGF
Mn
Z
MRFP
PSTN/ISDN
Gq'
Other IP Networks
Mj
Resource and Admission Control Function
MG
Ic
Mk
BGCF
Mp
GW
IWF
Mk
Mr
P-CSCF
Ib
P3
Mi
Gm
Gq'
Iw
SLF
Mw/Mk/Mm
I/S-CSCF
Mw
Z
Charging
Functions
PSTN/ISDN Emulation logic
Sh
e2
e2
Rf/Ro
Other types of service logic
Ut2
Network
Attachement
Control
Function
Rf/Ro
T- MGF
IP Transport Stratum (Access and Core)
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
I- BGF
15
IMS-based PES functional entities
ITU-T
o Access Gateway Control Function (AGCF)
• Acts as an MGC for controlling media gateways functions located in
residential and access gateways.
• Interacts with the resource and admission control function (RACF)
• Interacts with the network attachment Control Function (NACF) to retrieve
line profile information.
• Performs signalling inter-working between SIP and analogue signalling
Other functional entities which are the same as in IMS are:
o Multimedia Resource Function Controller (MRFC)
o Media Gateway Control Function (MGCF)
o Proxy Call Session Control Function (P-CSCF)
o Service Call Session Control Function (S-CSCF)
o Interrogating Call Session Control Function (I-CSCF)
o Breakout Gateway Control Function (BGCF)
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
16
IMS-based emulation reference points
ITU-T
o Reference points are mainly those
identified for IMS
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
17
Future work
ITU-T
o Completion of activities on finalizing
PSTN/ISDN emulation functional
architecture
o Addressing OAM, management and
control & signalling aspects
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
18
Conclusion
ITU-T
o Substantial progress has been made in
defining PSTN/ISDN functional architecture
as part of NGN
o Work is in progress for PSTN/ISDN emulation
requirements and framework
o More works needs to be done to identify
protocols at each reference point
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
19
List of Acronyms
ITU-T
ABG-FE
AGC-FE
AMG-FE
AS-FE
BGC-FE
CCF
CDR
CS
CTF
FE
IBC-FE
IBG-FE
ICMP
Access Border Gateway Functional
Entity
Access Gateway Control Functional
Entity
Access Media Gateway Functional
Entity
Application Server Functional Entity
Breakout Gateway Control
Functional Entity
Charging Collection Function
Call Detail Record
Call Server
Charging Trigger Function
Functional Entity
Interconnection Border Gateway
Control Functional Entity
Interconnection Border Gateway
Functional Entity
Internet Control Message Protocol
IMS
IP Multimedia
Subsystem
ISDN
Integrated Services Digital Network
MGC-FE Media Gateway Control Functional
Entity
MRC-FE Media Resource Control Functional
Entity
MRP-FE
Media Resource Processing
Functional Entity
PSTN
Public Switched Telephone
Network
RACF
Resource and Admission Control
Functions
RAN
Radio Access Network
RF
Routing Function
SIP
Session Initiation
Protocol
SS-FE
Service Switching Functional Entity
SUP-FE
Service User Profile Functional
Entity
TMG-FE Networks“
Trunk Media Gateway Functional
ITU-T Workshop on “Next Generation
Hanoi, Vietnam, 15-16 May 2006 Entity
20
ITU-T
Thank you for your attention
ITU-T Workshop on “Next Generation Networks“
Hanoi, Vietnam, 15-16 May 2006
21