International Telecommunication Union
What has still to be defined?
Network Attachment Subsystem and
Protocols
Keith Mainwaring
Technical Leader, Cisco
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006
Applications
ANI
Management functions
Application
Application
Application Support Functions & Service Support Functions
(may include own Authentication, Authorization and Accounting)
S-6: S. Authentication S-12: Network Signaling
S-5: S. User & Authorization FE
S-14: Media Resource Interworking FE
Profile FE
Broker FE Other NGN
S-3: Interrogating Call S-7: Interconnection
Service Control
Service Control
S-4: Subscription Session Control FE
Locator FE Border Gateway
S-15:Multimedia Control FE
Service FE
S-2: Proxy Call Session S-10: Breakout
Control FE Gateway Control FE
S-1: Serving Call Session Control FE
S-11: User Signaling S-8: Access GW S-9: Media GW
S-13: Media Resource Control FE
Interworking FE Control FE Control FE
other IP MM
Network
NACF RACF
T-14: Policy Decision FE (e.g. IMS)
T-12: T. User
Profile FE
T-15: Access Transport T-16 Core Transport
T-13: Resource Control FE Resource Control FE
T-11:
T. Location
T. Authentication
management
NGN &Authorization
FE
FE
End-User UNI
Function T-10: T-9:
T-8:
T. Network Access Control FE Signalling
Media
Legacy Gateway
Resource
Terminal FE
Processing
FE
T-6:
Internet
Core Transport
Core Transport
RGW
T-4: Access Inter-
Customer connection
Relay FE T-5:
Network Border
Access
Border Gateway FE
T-2: Access
Node FE T-3: Edge Gateway
Node FE FE T-7:
NGN Trunk
Terminal T-1: Access Media PSTN/ISDN
Media Gateway
Gateway FE
Legacy FE Access Packet Transport Functions Core Packet Transport Functions
Terminal
Scope of NGN
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 2
Status of work in ITU-T
o Overall architecture defined
o NASS still not fully defined in ITU-T (ETSI TISPAN
have approved a specification)
o SG11 protocol specifications not yet complete
• Resource & Admission Control protocols most advanced
(a number of equivalent interface specifications already
approved by ETSI TISPAN)
• IMS not yet addressed in SG 11 (ETSI TISPAN set
available)
• Draft SIP UNI & NNI profiles being produced by SG11
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 3
Network Attachment Control Functions
o Dynamic provision of IP address and other user
equipment configuration parameters.
o Authentication of user access network, prior or
during the IP address allocation procedure.
o Authorisation of user access network, based on
user profiles (e.g. access transport subscription).
o Access network configuration, based on user
profiles.
o Location management.
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 4
ETSI TISPAN NASS Architecture
Service control
subsystems and
applications
e2 Resource
e2
e4 and
CLF Admission
Control
a2 a4 e5 Subsystem
CNGCF
CPECF NACF UAAF PDBF
e3 a1 a3
e1 e1
TE CNG ARF AMF
UE
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 5
NASS Functional entities
o CNGCF (Customer Network Gateway Configuration Function) - used during initialization and
update of the UE to provide the UE with configuration information (e.g. configuration of a
firewall internally in the UE and QoS marking of IP packets) additional to the network
configuration data provided by the NACF.
o ARF (Access Relay Function) - relay between the CNG and the NASS that inserts local
configuration information.
o AMF (Access Management Function) - translates the network access requests sent by the UE
and forwards requests for allocation of an IP address and possibly additional network
configuration parameters to/from the NACF and forwards requests to the User Access
Authorisation Function (UAAF) to authenticate the user, authorize or deny the network
access, and retrieve user-specific access configuration parameters. If PPP is used the AMF
terminates the PPP connection and acts as a RADIUS client if the UAAF is implemented in a
RADIUS server.
o NACF (Network Access Configuration Function) - responsible for the IP address allocation.
Typically implemented as a DHCP or RADIUS server.
o UAAF (User Access Authorisation Function) - performs user authentication and authorisation
checking, based on user profiles. Communication between UAAFs in different administrative
domains is provided by the e5 interface allowing a UAAF-proxy to request the UAAF-server
for user authentication and authorization and allowing the UAAF-proxy to forward accounting
data for the particular user session to the UAAF-server.
o PDBF (Profile Database Function) - contains user authentication data (e.g. user identity, list
of supported authentication methods, and authentication keys). It may be co-located with
UAAF (the interface between them is not to be standardized).
o CLF (Connectivity Session Location and Repository Function) - registers the association
between the IP address allocated to the UE and related network location information. The
CLF has interfaces to the AF (e.g. P-CSCF) and to the RACS.
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 6
e2 interface
o Enables Application Functions (AF), such as an IMS P-CSCF
or a Presence Network Agent (PNA) to retrieve IP-
connectivity related session data from the NASS CLF
o Protocol is based on Diameter (RFC 3588)
o The AF can request the following information for a specific
subscriber (identified by a globally unique IP address or a
subscriber identifier):
• Subscriber-id;
• Location information;
• RACS contact point;
• Access network type (ATM, Ethernet or Unknown); and
• Terminal Type.
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 7
e4 interface
o Enables the exchange of IP-connectivity related session data between the NASS CLF and the
Access - RACF in the RACS
o The protocol on this interface is based on Diameter
o The following information can be transferred from the CLF to the A-RACF:
• Initial Gate Setting
• List of allowed destinations
• Up-Link Subscribed Bandwidth
• Down-Link Subscribed Bandwidth
• QoS Profile Information
• Transport service class
• Media-Type
• Up-Link Subscribed Bandwidth
• Down-Link Subscribed Bandwidth
• Maximum Priority
• Requestor Name
o The Access Profile is “pushed” from the CLF to the A-RACF when an IP address has been
allocated to a subscriber or in the case of a modification occurring on a profile that has already
been pushed to the RACS and “pulled” by the A-RACF from the CLF after a restart or upon
reception of a resource reservation request associated with an IP-Address for which no record is
stored.
o The CLF can also report the loss of IP connectivity enabling the RACS to remove the access
profile from its internal data base. This occurs when the allocated IP address is released (e.g.
DHCP leased timer expiry) or due to the release of the underlying layer 2 resources.
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 8
Outline of NGN QoS Control (ETSI terminology)
e2 P-CSCF
e2 AF (e.g. P-CSCF)
e2
NASS
NASS 2 3
Service Request Resource
1 e4 (e.g. SIP INVITE) Request
Authentication SPDF
A-RACF 4
Authorisation
Configuration Resource 5
Request Policy Push
UE BGF
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 9
ITU-T Resource Control Protocol Drafts
SG11 draft protocol
specifications for Rs, Rp,
Rw, Rc, Rt and Rd; not for
Ri, Rn nor Ru
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 10
IMS Background
o 3GPP application of SIP with modifications to support:
• GSM business model – subscriber of a ”Home” network operator
• GSM handset capabilities (SIM for authorisation)
• Not primarily for voice – this is likely to be supported on the circuit-
switched domain for some time – but for presence, IM, push-to-
talk....
o ETSI TISPAN NGN IMS
• Fixed network access with ”nomadicity”
• Ambition to achieve Fixed Mobile Convergence
o ITU-T
• Moving to adopt IMS as one element of broad NGN
o PacketCable2.0
• Moving to adopt IMS model – but tailored to cable requirements
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 11
ETSI TISPAN NGN IMS – relationship to 3GPP & IETF
ETSI TISPAN NGN
Architecture & Requirements
IMS 3GPP
IMS
IETF SIP
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 12
ETSI TISPAN IMS Architecture cf. 3GPP IMS
o Addition of the e2 interface in the TISPAN
architecture between the P-CSCF and the NASS
(Network Attachment Subsystem) Connectivity
Session Location and Repository Function (CLF)
o Use of the Gq’ interface rather than Gq as in the
3GPP architecture
o Substitution of the UPSF (User Profile Server
Function) for the HSS (equivalent to HSS with
HLR stripped out)
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 13
ETSI TISPAN IMS cf. 3GPP IMS Release 7
Charging
o ETSI TISPAN NGN Release 1 only supports off-line charging.
SIP Protocol
o UEs may support neither ISIM nor USIM.
o Adds NASS bundled authentication.
o Allows a transport mechanism without a security association.
o Inclusion of Gq’ interface to P-CSCF.
o Addition of e2 interface.
o Added capability for the Proxy role for “Rejecting anonymous
requests in the Session Initiation Protocol (SIP)” and the status code
433 (Anonymity Disallowed).
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 14
TISPAN IMS – Supplementary Service Support
o NGN Cdiv
o NGN CONF
o NGN MWI
o NGN OIP/OIR
o NGN TIP/TIR
o NGN CW
o NGN HOLD
o NGN AoC
o NGN CCBS/CCNR
o NGN ACR – CB
o NGN MCID
o NGN Explicit Communication Transfer
o NGN Presence Stage 3
o NGN Hold corrections/alignment
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 15
Summary
o NGN Architecture specifications stable
o Currently, no ITU-T interface protocol
specifications finalised but some RACF interface
specifications and SIP UNI & NNI profiles should
be approved shortly & a number of ETSI and
many fundamental IETF specifications are
available.
ITU-T/ITU-D Workshop "Standardization and Development of Next Generation Networks"
Dar es Salaam, 3-5 October 2006 16