SIST ES 282 001 V3.4.1:2009

ETSI Standard
Telecommunications and Internet converged Services and
Protocols for Advanced Networking (TISPAN);
NGN Functional Architecture
2 ETSI ES 282 001 V3.4.1 (2009-09)

Reference
RES/TISPAN-02067-NGN-R3
Keywords
architecture, functional
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3 ETSI ES 282 001 V3.4.1 (2009-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 Overall architecture . 9
5 Transport layer . 11
5.1 Transport control sublayer . 11
5.1.1 Network Attachment SubSystem (NASS) . 11
5.1.2 Resource and Admission Control Subsystem (RACS) . 12
5.2 Transport processing functions . 13
5.2.1 Border Gateway Function (BGF) . 14
5.2.1A Resource Control Enforcement Function (RCEF) . 15
5.2.2 Void . 15
5.2.3 Access Relay Function (ARF) . 15
5.2.4 Media Gateway Function (MGF) . 15
5.2.5 Multimedia Resource Function Processor (MRFP) . 16
5.2.6 Signalling Gateway Function (SGF) . 16
5.2.7 Access Management Function (AMF) . 16
5.2.8 Basic Transport Function (BTF) . 16
5.2.8.1 Elementary Forwarding Function (EFF) . 17
5.2.8.2 Elementary Control Function (ECF) . 17
6 Service Layer Model . 17
6.1 The "Core" IP Multimedia Subsystem (IMS) . 17
6.2 The PSTN/ISDN Emulation subsystem (PES) . 18
6.3 The IPTV Subsystem. 18
6.4 Void . 18
6.5 Common components . 18
6.5.1 User Profile Server Function (UPSF) . 19
6.5.2 Subscription Locator Function (SLF) . 19
6.5.3 Application Server Function (ASF) . 19
6.5.4 Void . 19
6.5.5 InterWorking Function (IWF). 19
6A Charging and Data Collection Functions . 20
7 NGN Interconnection . 20
7.1 General . 20
7.2 Interconnection reference points and functions . 21
7.2.1 Interconnection at the transport layer . 21
7.2.1.1 Transport processing sublayer . 21
7.2.1.2 NASS . 21
7.2.1.3 RACS . 22
7.2.2 Interconnection at the Service Layer . 22
7.3 NGN Interconnection types . 23
7.3.1 SoIx in the NGN Architecture . 23
7.3.2 CoIx in the NGN Architecture . 24
7.3.3 PSTN Interconnection types . 25
7.3.4 NGN Direct and Indirect interconnection modes . 26
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4 ETSI ES 282 001 V3.4.1 (2009-09)
8 User Equipment (UE) . 29
8.1 Overview . 29
8.2 Authentication . 29
8.3 Reference points . 30
8.3.1 Reference points to the core IMS . 30
8.3.2 Reference points to the PSTN/ISDN Emulation subsystem . 30
8.3.3 Reference points with applications . 31
8.3.4 Reference points with the NASS . 31
8.3.5 Reference points with the RACS . 31
8.3.6 Reference points with transport processing functions. 31
8.3.7 Reference points with access media gateway functions. 31
9 Security aspects . 31
9.1 Security architecture . 31
9.2 Threat Vulnerability and Risk Analysis (TVRA) . 31
9.3 Prevention of Unsolicited Communication (PUC) . 31
Annex A (informative): Example of physical configuration for xDSL access . 32
Annex B (informative): Transport architecture for multicast . 33
B.1 Introduction . 33
B.2 Multicast Functions in Transport Plane . 33
Annex C (informative): Example of physical configuration for WiMAX access . 35
Annex D (informative): Change history: . 36
History . 37

ETSI
5 ETSI ES 282 001 V3.4.1 (2009-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This ETSI Standard (ES) has been produced by ETSI Technical Committee Telecommunications and Internet
converged Services and Protocols for Advanced Networking (TISPAN).
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6 ETSI ES 282 001 V3.4.1 (2009-09)
1 Scope
The present document describes the overall TISPAN NGN functional architecture, its subsystems and the relationships
between them.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1] ETSI TS 102 144: "Services and Protocols for Advanced Networks (SPAN); MTP/SCCP/SSCOP
and SIGTRAN (Transport of SS7 over IP); Stream Control Transmission Protocol (SCTP)
[Endorsement of RFC 2960 and RFC 3309, modified]".
[2] ITU-T Recommendation Y.2011: "General principles and general reference model for next
generation networks".
[3] ETSI TS 123 002: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); Network architecture (3GPP TS 23.002 version 7.3.1)".
[4] ETSI TS 123 228: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2
(3GPP TS 23.228)".
[5] ETSI ES 282 004: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); NGN Functional Architecture; Network Attachment
Sub-System (NASS)".
[6] ETSI ES 282 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Resource and Admission Control Sub-System (RACS):
Functional Architecture".
[7] ETSI ES 282 007: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IP Multimedia Subsystem (IMS); Functional architecture".
[8] ETSI ES 282 002: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); PSTN/ISDN Emulation Sub-system (PES); Functional
architecture".
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7 ETSI ES 282 001 V3.4.1 (2009-09)
[9] ETSI TS 182 012: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IMS-based PSTN/ISDN Emulation Sub-system (PES);
Functional architecture".
[10] ETSI TS 182 027: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IPTV Architecture; IPTV functions supported by the IMS
subsystem".
[11] ETSI TS 182 028: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IPTV Architecture; Dedicated subsystem for IPTV functions".
[12] ETSI TS 185 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Customer Network Gateway (CNG) Architecture and
Reference Points".
[13] ETSI TS 185 006: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Customer Devices architecture and Reference Points".
[14] ETSI TS 181 005: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Service and Capability Requirements".
[15] ITU-T Recommendation G.8010: "Architecture of Ethernet layer networks".
[16] ETSI TS 182 025: " Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Business Trunking; Architecture and functional description".
[17] ETSI TS 187 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); NGN Security; Security Architecture".
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI TS 187 015: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Specifications for PUC (Prevention of Unsolicited
Communication) in the NGN".
[i.2] ETSI TR 187 002: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); TISPAN NGN Security (NGN-SEC); Threat, Vulnerability and
Risk Analysis".
[i.3] IEEE 802.16-2004: "IEEE Standard for Local and metropolitan area networks; Part 16: Air
Interface for Fixed Broadband Wireless Access Systems".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
access network: collection of network entities and interfaces that provide the underlying IP transport connectivity
between end user devices and NGN entities
core network: portion of the delivery system composed of networks, systems equipment and infrastructures,
connecting the service providers to the access network
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8 ETSI ES 282 001 V3.4.1 (2009-09)
functional entity: entity that comprises a specific set of functions at a given location
NOTE: Functional entities are logical concepts, grouping of functional entities are used to describe practical
physical realizations.
user equipment: one or more devices allowing a user to access services delivered by TISPAN NGN networks
NOTE: This includes devices when under user control commonly referred to as IAD, ATA, RGW, TE, etc., UE
does not include network controlled entities such as network terminations and access gateways.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3GPP Third Generation Project Partnership
AMF Access Management Function
A-MGF Access Media Gateway Function
AN Access Node
ARF Access Relay Function
AS Application Server
ASF Application Server Function
ASN GW Access Service Network GateWay
ATA Analogue Terminal Adaptor
AUC AUthentication Centre
BGF Border Gateway Function
BGW Border GateWay
BNG Broadband Network Gateway
BRAS Broadband Remote Access Server
BS Base Station
BTF Basic Transport Function
C-BGF Core Border Gateway Function
CND Customer Network Device
CNG Customer Network Gateway
CPN Customer Premises Network
CSCF Call Session Control Function
DHCP Dynamic Host Configuration Protocol
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Multiplexer
ECF Elementary Control Function
EFF Elementary Forwarding Function
ENUM tElephone NUmber Mapping
GPON Gigabit-capable Passive Optical Network
HLR Home Location Register
HSS Home Subscriber Server
IAD Integrated Access Device
IBCF Interconnection Border Control Function
I-BGF Interconnection-Border Gateway Function
I-CSCF Interrogating-Call Session Control Function
IGMP Internet Group Management Protocol
IMS IP Multimedia Subsystem
IMS-MGW IMS-Media GateWay
IP Internet Protocol
ISDN Integrated Services Digital Network
ISUP ISDN User Part
IVR Interactive Voice Response
IWF InterWorking Function
MAC Media Access Control (layer)
MGCF Media Gateway Control Function
MGF Media Gateway Function
MLD Multicast Listener Discovery
MPLS MultiProtocol Label Switching
MRFP Multimedia Resource Function Processor
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9 ETSI ES 282 001 V3.4.1 (2009-09)
MTP Message Transfer Part
NAPT Network Address and Port Translation
NAPT-PT NAPT and Protocol Translation
NASS Network Attachment SubSystem
NAT Network Address Translation
NGCN Next Generation Corporate Networks
NGN Next Generation Network
NNI Network to Network Interface
OLT Optical Line Termination
ONT Optical Network Termination
ONU Optical Network Unit
OSA Open Service Access
PES PSTN/ISDN Emulation Subsystem
PHY PHYsical (layer)
PIM Protocol Independent Multicast
PPP Point-to-Point Protocol
PSTN Public Switched Telephony Network
PUC Prevention of Unsolicited Communication
RACS Resource and Admission Control Subsystem
RADIUS Remote Access Dial In User Service
RCEF Resource Control Enforcement Function
RGW Residential GateWay
R-MGF Residential Media Gateway Function
SCCP Signalling Connection Control Part
SCTP Stream Control Transmission Protocol
SGCF Signalling Gateway Control Function
SGF Signalling Gateway Function
SGW Signalling GateWay
SIP Session Initiation Protocol
SLF Subscription Locator Function
TDM Time Division Multiplexing
TE Terminal Equipment
TF Transport Function
TGCF Trunking GateWay Control Function
TGW Trunking GateWay
T-MGF Trunking-Media Gateway Function
TVRA Threat Vulnerability and Risk Analysis
UE User Equipment
UPSF User Profile Server Function
WiMAX Worldwide Interoperability for Microwave Access
4 Overall architecture
The NGN functional architecture described in the present document complies with the ITU-T general reference model
for next generation networks [2] and is structured according to a service layer and an IP-based transport layer.
The service layer comprises the following components:
• the core IP Multimedia Subsystem (IMS);
• the PSTN/ISDN Emulation Subsystem (PES);
• other multimedia subsystems (e.g. IPTV Dedicated Subsystem) and applications;
• common components (i.e. used by several subsystems) such as those required for accessing applications,
charging functions, user profile management, security management, routing data bases (e.g. ENUM), etc.
This subsystem-oriented architecture enables the addition of new subsystems over the time to cover new demands and
service classes. It also provides the ability to import (and adapt) subsystems defined by other standardization bodies.
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Other networks
User Equipment
10 ETSI ES 282 001 V3.4.1 (2009-09)
IP-connectivity is provided to NGN user equipment by the transport layer, under the control of the Network Attachment
SubSystem (NASS) and the Resource and Admission Control Subsystem (RACS). These subsystems hide the transport
technology used in access and core networks below the IP layer.
The architecture described in the present document and related subsystems specifications is a functional architecture.
Each subsystem is specified as a set of functional entities and related interfaces. As a result implementers may choose to
combine functional entities where this makes sense in the context of the business models, services and capabilities
being supported. Where functional entities are combined the interface between them is internal, is hidden and
un-testable.
Figure 1 provides an overview of the NGN architecture. An example of realization of this functional architecture, with
an xDSL-based access network is provided in annex A. An example of realization of this functional architecture, with a
WiMAX-based access network is provided in annex B.
Applications
Service Layer
Other
Subsyst ems
User
profiles
Core IMS
PSTN/ISDN
Emulat ion
Subsyst em
Transport Layer
Network
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
Transport processing functions

Figure 1: TISPAN NGN overall architecture
The functional entities that make up a subsystem may be distributed over network/service provider domains (see
figure 2). The network attachment subsystem may be distributed between a visited and a home network. Service-layer
subsystems that support nomadism may also be distributed between a visited and a home network.
Visited Network Home Network
Distributed Subsystem
Core Network Core Network
(control) (control)
UE
Access
Core Core
Network Networks Networks
(transfer) (transfer) (transfer)

Figure 2: Distributed subsystems
This architecture supports the service capabilities and requirements identified in TS 181 005 [14].
An access network comprises an access segment and an aggregation segment (figure 2a). The access segment (also
known as "last mile segment" stretches from the customer premises to the first network node (also known as the "access
node"). The aggregation segment comprises the transport network elements enabling one or more access nodes to be
connected to a core network through an IP Edge Router, at the Di reference point.
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11 ETSI ES 282 001 V3.4.1 (2009-09)
NOTE 1: In configurations where the access segment uses the DSL technology, the aggregation segment generally
uses ATM or Giga Ethernet. The IP Edge is known as a Broadband Remote Access Server (BRAS) or
Broadband Network Gateway (BNG) and the access node is a DSLAM.
NOTE 2: In configurations where the access segment uses the GPON technology, the aggregation segment uses
Giga Ethernet. The IP Edge is known as a Broadband Network Gateway (BNG) and the functions of the
access node are distributed between the Optical Line Termination (OLT) and the Optical Network
Unit (ONU)/Optical Network Termination (ONT).
Access
IP-Edge
Transport Network Elements
Node
Di
Access Segment Aggregation Segment

Figure 2a: Access and aggregation segments
5 Transport layer
The transport layer comprises a transport control sublayer on top of transport processing functions in the access and
core networks. Equivalent functionality in the User Equipment (UE) is defined in clause 8.
The transport control sublayer is further divided in two subsystems:
• the Network Attachment SubSystem (NASS);
• the Resource and Admission Control Subsystem (RACS).
5.1 Transport control sublayer
5.1.1 Network Attachment SubSystem (NASS)
The Network Attachment Subsystem provides the following functionalities:
• dynamic provision of IP addresses and other terminal configuration parameters;
• authentication taking place at the IP layer, prior or during the address allocation procedure;
• authorization of network access based on user profiles;
• access network configuration based on user profiles;
• location management taking place at the IP layer.
The NGN architecture does not mandate a single NASS instance to support multiple access networks. This does not
prevent operators from deploying NASS functions that are common to multiple access networks (e.g. one user profile
database common to different access networks).
NOTE: The user profiles mentioned above are related to the access subscription only.
ETSI
User
Equipment
Core Network
User Equipment
12 ETSI ES 282 001 V3.4.1 (2009-09)
The NASS interfaces with the following entities (see figure 2b):
• the user equipment at the e3 reference point for configuration purposes;
• transport processing entities acting as relays to/from the user equipment for address allocation, authentication
and authorization purposes (a1 and a3 reference points);
• the Resource and Admission Control Subsystem at the e4 reference point for exporting subscriber access
profile information;
• service-control subsystems and applications in the service layer at the e2 reference point for exporting
information on access sessions and supporting notification services.
Applications
Service Layer
….
User
profiles
…
Service
Cont rol
Subsyst ems
e2
Transport Layer
e3 Network
e4
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
a1,a3
Transport processing functions

Figure 2b: NASS external reference points
Further details about the functionalities and architecture of the NASS can be found in ES 282 004 [5].
5.1.2 Resource and Admission Control Subsystem (RACS)
RACS is the TISPAN NGN subsystem responsible for the implementation of procedures and mechanisms handling
policy-based resource reservation and admission control for both unicast and multicast traffic in access networks, core
networks and customer premises networks.
Besides acting as a resource control framework, RACS also includes support for controlling Network Address and Port
Translation (NAPT) at the edge of networks and assisting in remote NAT traversal. Furthermore, RACS also covers
aspects related to the setting and modification of traffic policies, end to end quality of service and transport-level
charging.
The RACS interfaces with transport processing functions at the Re and Ia reference points and with the following
subsystems (see figure 2c):
• The Network Attachment Subsystem at the e4 reference point for obtaining subscriber access profile
information.
• Service-control subsystems and applications in the service layer at the Gq' reference point for exposing the
services it provides.
ETSI
User Equipment
13 ETSI ES 282 001 V3.4.1 (2009-09)
Applications
Service Layer
….
User
profiles
…
Service
Cont rol
Subsyst ems
Gq'
Transport Layer
Gq'
Network
e4
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
Re Ia
Transport processing functions
Transport Processing Functions

Figure 2c: RACS external reference points
Further details about the functionalities and architecture of the RACS are defined in ES 282 003 [6].
5.2 Transport processing functions
Transport processing functions in the access and core networks include basic elementary functions supporting packet
forwarding and routing, and more specific group of functions defined as functional entities.
These are:
• Media Gateway Function (MGF).
• Border Gateway Function (BGF).
• Resource Control Enforcement Function (RCEF).
• Access Relay Function (ARF).
• Signalling Gateway Function (SGF).
• Multimedia Resource Function Processor (MRFP).
• Access Management Function (AMF).
• Basic Transport Function (BTF).
Figure 3 provides an overview of the transport processing functions and their relationships to the other components of
the architecture.
ETSI
Other networks
User Equipment
14 ETSI ES 282 001 V3.4.1 (2009-09)
Service Layer
Transport control functions
RACS
NASS
Z, S/T
A-MGF
SGF
MRFP
T-MGF
e1 e1 Di
ARF AMF
Ds
RCEF C-BGF
I-BGF
BTF
Dj Di Ds
Iz
Transport processing functions

Figure 3: Transport processing functions overview
5.2.1 Border Gateway Function (BGF)
A Border Gateway Function (BGF) provides the interface between two IP-transport domains. It may reside at the
boundary between an access network and the customer premises equipment, between an access network and a core
network or between two core networks. It encompasses the functionality of a Resource Control Enforcement Function
(RCEF) defined in clause 5.2.1A and may also support one or more of the following elementary functions:
• usage metering;
• allocation and translation of IP addresses and port numbers (NAPT);
• interworking between IPv4 and IPv6 networks (NAPT-PT);
• assistance in hosted NAT traversal; and
• transcoding (see notes 1 and 2).
NOTE 1: The BGF is not the only place in the architecture where transcoding may be performed: MRFPs can also
perform transcoding.
NOTE 2: To support this function a BGF needs to be media aware.
A BGF may interact with entities in the transport control sublayer for the purpose of controlling one or more of the
functionalities it implements.
The present document identifies two main types of BGF:
• the Core BGF (C-BGF) that sits at the boundary between an access network and a core network, at the core
network side;
• the Interconnection BGF (I-BGF) that sits at the boundary between two core networks.
The C-BGF interfaces access networks at the Di reference point and other transport processing functions of the core
network at the Ds reference point.
The I-BGF interfaces other core networks at the Iz reference point and other transport processing functions of the core
network at the Ds reference point.
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Other core networks
15 ETSI ES 282 001 V3.4.1 (2009-09)
Each BGF instance implements different subsets of the functionalities identified for a generic BGF, depending on their
location and network operators' policies.
C-BGF I-BGF
Access Network Other Transport Processing Functions
Di Ds Ds Iz
Core Network
Figure 3a: Border Gateway Control Functions
Further details are available in the RACS specification ES 282 003 [6].
NOTE 3: The C-BGF and the I-BGF encompass, respectively, the functionality of the IMS Access Gateway and of
the Translation Gateway defined in TS 123 228 [4].
5.2.1A Resource Control Enforcement Function (RCEF)
A Resource Control Enforcement Function (RCEF) is a transport processing functional entity that supports one or more
of the following elementary functions:
• opening and closing gates (i.e. packets filtering depending on "IP address/port");
• packet marking for outgoing traffic;
• policing of incoming traffic;
• resource allocation for upstream and downstream traffic.
An RCEF can reside in any transport segment (i.e. access, aggregation, or core) or at its edges. Multiple RCEF
instances may exist in the same transport segment.
A RCEF may interact with entities in the RACS for the purpose of controlling one or more of the elementary functions
it implements (see ES 282 003 [6] for more details). It can receive/send information flows from/to a BTF and handle
corresponding requests/answers to/from the RACS.
5.2.2 Void
5.2.3 Access Relay Function (ARF)
The Access Relay Function (ARF) acts as a relay between the user equipment and the Network Attachment
SubSystem (NASS). It receives network access requests from the user equipment and forwards them to the NASS.
Before forwarding a request, the ARF may also insert local configuration information.
NOTE: When using PPP, the ARF may act as a PPPoE relay. When using DHCP, the ARF acts as a DHCP Relay
Agent.
5.2.4 Media Gateway Function (MGF)
A Media Gateway Function (MGF) provides the media mapping and/or transcoding functions between an IP-transport
domain and switched circuit network facilities (trunks, loops). It may also perform media conferencing and send tones
and announcements.
The present document identifies two types of MGF that may exist in the operator's network:
• the Access MGF (A-MGF) that connects legacy access types (e.g. analogue or ISDN) to the NGN;
• the Trunking MGF (T-MGF) that sits at the boundary between an IP core network and a Circuit-Switched
network.
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16 ETSI ES 282 001 V3.4.1 (2009-09)
NOTE 1: An MGF may also be embedded in the user equipment (see clause 8). This type of MGF is known as a
Residential MGF (R-MGF).
NOTE 2: The T-MGF functional entity is identical to the IMS-MGW defined in TS 123 002 [3], although a
network node implementing this functional entity in an NGN network and a network node implementing
it in a 3GPP network may differ in terms of supported resources (e.g. codecs) and configuration.
5.2.5 Multimedia Resource Function Processor (MRFP)
A Multimedia Resource Function Processor (MRFP) provides specialized resource processing functions beyond those
available in media gateway functions. This includes resources for supporting multimedia conferences, sourcing
multimedia announcements, implementing IVR capabilities and media content analysis.
NOTE: This functional entity is identical to the MRFP defined in TS 123 002 [3], although a network node
implementing this functional entity in an NGN network and a network node implementing it in a 3GPP
network may differ in terms of supported resources and configuration.
5.2.6 Signalling Gateway Function (SGF)
The Signalling Gateway Function (SGF) performs the signalling conversion (both ways) at transport level between the
SS7 based transport of signalling and IP based signalling transport. The functionality of the SGF encompasses:
• reliable transport of SS7 upper layer signalling over IP, using SCTP procedures [1];
• SS7 firewall functionality - as far as applicable - by screening within MTP and SCCP headers.
NOTE: This functional entity is identical to the SGW defined in TS 123 002 [3], although a network node
implementing this functional entity in an NGN network and a network node implementing it in a 3GPP
network may differ in terms of configuration.
5.2.7 Access Management Function (AMF)
The Access Management Function (AMF) translates network access requests issued by the UE into a format that can be
understood by the NASS.
NOTE: In case PPP is applied, the AMF terminates the PPP connection and provides the inter-working with the
interface to the network attachment subsystem e.g. using an AAA protocol (RADIUS or Diameter).
5.2.8 Basic Transport Function (BTF)
All transport segments comprise one or more basic transport functions (BTF) which contain two elementary transport
processing functions: Elementary Forwarding Functions (EFF) and Elementary Control Functions (ECF). Physical
network elements (e.g. a bridge, a router etc.) - typically contain a BTF and might contain additional functional entities,
e.g. RCEF.
Figure 3b shows the BTF, the elementary functions comprising the BTF as well as the relation to other functional
entities of the NGN. Reference points BTF-BTF, RCEF-BTF, and BGF-BTF are outside the scope of the current
TISPAN Release due to their implementation specific nature and the fact that some of which are typically internal to a
device.
ETSI
17 ETSI ES 282 001 V3.4.1 (2009-09)
RACS
Re Ia
Dj Di Di,Ds Ds,Iz
RCEF BGF
EFF ECF
BTF
Figure 3b: Transport Function (TF) in the context of other functional entities of the NGN
5.2.8.1 Elementary Forwarding Function (EFF)
An Elementary Forwarding Function (EFF) forwards traffic data received on one flow point "In-FP" (flow point is used
here similar to ITU-T Recommendation G.8010 [15]) to one or more flow point(s) "Out-FP(i)", i = 0.n of a transport
element; where "In-FP" is not contained within the set of "Out-FP(i), i = 0.n". Consequently, for a unicast type of
operation there is exactly one Out-FP (i.e. i = 1), while for multicast type of operation the set of "Out-FP(i)" can contain
any number of flow points (including the case where "Out-FP(i)" equals the empty set).
5.2.8.2 Elementary Control Function (ECF)
An Elementary Control Function (ECF) processes control protocol data for unicast (e.g. path-coupled signalling as well
as multicast data (e.g. routing protocol) received on one flow point. As a result of this processing, the ECF might decide
to:
• send control protocol data (including events to trigger policy evaluation) to other ECF;
• interact with one or more EFF to establish new or modify existing forwarding behaviour of the EFF;
• interact with one or more instances of RCEF and/or BGF. This includes the ability to create events to trigger
policy evaluation in RCEF and/or BGF.
ECF may also receive requests from RCEF to perform policy enforcement (e.g. trigger transport control protocol
actions) and reply back to RCEF indicating the result of the requested operation.
6 Service Layer Model
6.1 The "Core" IP Multimedia Subsystem (IMS)
The IP Multimedia Subsystem (IMS) core component of the NGN architecture (Core IMS) supports the provision of
SIP-based multimedia services to NGN terminals. It also supports the provision of PSTN/ISDN simulation services.
NOTE: The "Core IMS" is a subset of the 3GPP IMS defined in TS 123 002 [3] which is restricted to the session
control functionalities. Application Servers (AS) and transport/media related functions such as the
Multimedia Resource Function Processors (MRFP) and the IMS Media GateWay function (IMS-MGW)
are considered to be outside the "Core IMS".
The architecture of this subsystem is further described in ES 282 007 [7].
ETSI
18 ETSI ES 282 001 V3.4.1 (2009-09)
6.2 The PSTN/ISDN Emulation subsystem (PES)
The PSTN/ISDN Emulation Subsystem supports the emulation of PSTN/ISDN services for legacy terminals connected
to the NGN, through residential gateways or access gateways.
Further details about the functionalities and architecture of the PSTN/ISDN emulation subsystem can be found in
ES 282 002 [8] and TS 182 012 [9] which define alternative functional architectures for this subsystem.
6.3 The IPTV Subsystem
The IPTV subsystem supports the provision of content on demand services and broadcast services using a dedicated
service control architecture described in TS 182 028 [11].
The TISPAN architecture also enables supporting IPTV services using the IP Multimedia Subsystem (see clause 6.1) as
described in TS 182 027 [10].
6.4 Void
6.5 Common components
The NGN architecture includes a number of functional entities that can be accessed by more than one subsystem.
These are:
• the User Profile Server Function (UPSF);
• the Subscription Locator Function (SLF);
• the Application Server Function (ASF);
• the InterWorking Function (IWF).
Figure 4 provides an overview of the common components and their relationships to the other elements of the
architecture.
ASF ASF
UPSF
(type 1) (type 2)
IWF
SLF To/From
other IP
networks
Service Control
Subsystems
Service Layer
Transport Layer
Transport control
Transport processing
Figure 4: Common components overview
ETSI
...

SLOVENSKI STANDARD
01-november-2009
Zlite telekomunikacijske in internetne storitve ter protokoli za napredno omreženje
(TISPAN) - Funkcijska arhitektura omrežja NGN
Telecommunications and Internet converged Services and Protocols for Advanced
Networking (TISPAN) - NGN Functional Architecture
Ta slovenski standard je istoveten z: ES 282 001 Version 3.4.1
ICS:
33.040.01 Telekomunikacijski sistemi Telecommunication systems
na splošno in general
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

ETSI Standard
Telecommunications and Internet converged Services and
Protocols for Advanced Networking (TISPAN);
NGN Functional Architecture
2 ETSI ES 282 001 V3.4.1 (2009-09)

Reference
RES/TISPAN-02067-NGN-R3
Keywords
architecture, functional
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ETSI
3 ETSI ES 282 001 V3.4.1 (2009-09)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 Overall architecture . 9
5 Transport layer . 11
5.1 Transport control sublayer . 11
5.1.1 Network Attachment SubSystem (NASS) . 11
5.1.2 Resource and Admission Control Subsystem (RACS) . 12
5.2 Transport processing functions . 13
5.2.1 Border Gateway Function (BGF) . 14
5.2.1A Resource Control Enforcement Function (RCEF) . 15
5.2.2 Void . 15
5.2.3 Access Relay Function (ARF) . 15
5.2.4 Media Gateway Function (MGF) . 15
5.2.5 Multimedia Resource Function Processor (MRFP) . 16
5.2.6 Signalling Gateway Function (SGF) . 16
5.2.7 Access Management Function (AMF) . 16
5.2.8 Basic Transport Function (BTF) . 16
5.2.8.1 Elementary Forwarding Function (EFF) . 17
5.2.8.2 Elementary Control Function (ECF) . 17
6 Service Layer Model . 17
6.1 The "Core" IP Multimedia Subsystem (IMS) . 17
6.2 The PSTN/ISDN Emulation subsystem (PES) . 18
6.3 The IPTV Subsystem. 18
6.4 Void . 18
6.5 Common components . 18
6.5.1 User Profile Server Function (UPSF) . 19
6.5.2 Subscription Locator Function (SLF) . 19
6.5.3 Application Server Function (ASF) . 19
6.5.4 Void . 19
6.5.5 InterWorking Function (IWF). 19
6A Charging and Data Collection Functions . 20
7 NGN Interconnection . 20
7.1 General . 20
7.2 Interconnection reference points and functions . 21
7.2.1 Interconnection at the transport layer . 21
7.2.1.1 Transport processing sublayer . 21
7.2.1.2 NASS . 21
7.2.1.3 RACS . 22
7.2.2 Interconnection at the Service Layer . 22
7.3 NGN Interconnection types . 23
7.3.1 SoIx in the NGN Architecture . 23
7.3.2 CoIx in the NGN Architecture . 24
7.3.3 PSTN Interconnection types . 25
7.3.4 NGN Direct and Indirect interconnection modes . 26
ETSI
4 ETSI ES 282 001 V3.4.1 (2009-09)
8 User Equipment (UE) . 29
8.1 Overview . 29
8.2 Authentication . 29
8.3 Reference points . 30
8.3.1 Reference points to the core IMS . 30
8.3.2 Reference points to the PSTN/ISDN Emulation subsystem . 30
8.3.3 Reference points with applications . 31
8.3.4 Reference points with the NASS . 31
8.3.5 Reference points with the RACS . 31
8.3.6 Reference points with transport processing functions. 31
8.3.7 Reference points with access media gateway functions. 31
9 Security aspects . 31
9.1 Security architecture . 31
9.2 Threat Vulnerability and Risk Analysis (TVRA) . 31
9.3 Prevention of Unsolicited Communication (PUC) . 31
Annex A (informative): Example of physical configuration for xDSL access . 32
Annex B (informative): Transport architecture for multicast . 33
B.1 Introduction . 33
B.2 Multicast Functions in Transport Plane . 33
Annex C (informative): Example of physical configuration for WiMAX access . 35
Annex D (informative): Change history: . 36
History . 37

ETSI
5 ETSI ES 282 001 V3.4.1 (2009-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This ETSI Standard (ES) has been produced by ETSI Technical Committee Telecommunications and Internet
converged Services and Protocols for Advanced Networking (TISPAN).
ETSI
6 ETSI ES 282 001 V3.4.1 (2009-09)
1 Scope
The present document describes the overall TISPAN NGN functional architecture, its subsystems and the relationships
between them.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1] ETSI TS 102 144: "Services and Protocols for Advanced Networks (SPAN); MTP/SCCP/SSCOP
and SIGTRAN (Transport of SS7 over IP); Stream Control Transmission Protocol (SCTP)
[Endorsement of RFC 2960 and RFC 3309, modified]".
[2] ITU-T Recommendation Y.2011: "General principles and general reference model for next
generation networks".
[3] ETSI TS 123 002: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); Network architecture (3GPP TS 23.002 version 7.3.1)".
[4] ETSI TS 123 228: "Digital cellular telecommunications system (Phase 2+); Universal Mobile
Telecommunications System (UMTS); LTE; IP Multimedia Subsystem (IMS); Stage 2
(3GPP TS 23.228)".
[5] ETSI ES 282 004: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); NGN Functional Architecture; Network Attachment
Sub-System (NASS)".
[6] ETSI ES 282 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Resource and Admission Control Sub-System (RACS):
Functional Architecture".
[7] ETSI ES 282 007: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IP Multimedia Subsystem (IMS); Functional architecture".
[8] ETSI ES 282 002: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); PSTN/ISDN Emulation Sub-system (PES); Functional
architecture".
ETSI
7 ETSI ES 282 001 V3.4.1 (2009-09)
[9] ETSI TS 182 012: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IMS-based PSTN/ISDN Emulation Sub-system (PES);
Functional architecture".
[10] ETSI TS 182 027: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IPTV Architecture; IPTV functions supported by the IMS
subsystem".
[11] ETSI TS 182 028: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); IPTV Architecture; Dedicated subsystem for IPTV functions".
[12] ETSI TS 185 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Customer Network Gateway (CNG) Architecture and
Reference Points".
[13] ETSI TS 185 006: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Customer Devices architecture and Reference Points".
[14] ETSI TS 181 005: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Service and Capability Requirements".
[15] ITU-T Recommendation G.8010: "Architecture of Ethernet layer networks".
[16] ETSI TS 182 025: " Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Business Trunking; Architecture and functional description".
[17] ETSI TS 187 003: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); NGN Security; Security Architecture".
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI TS 187 015: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Specifications for PUC (Prevention of Unsolicited
Communication) in the NGN".
[i.2] ETSI TR 187 002: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); TISPAN NGN Security (NGN-SEC); Threat, Vulnerability and
Risk Analysis".
[i.3] IEEE 802.16-2004: "IEEE Standard for Local and metropolitan area networks; Part 16: Air
Interface for Fixed Broadband Wireless Access Systems".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
access network: collection of network entities and interfaces that provide the underlying IP transport connectivity
between end user devices and NGN entities
core network: portion of the delivery system composed of networks, systems equipment and infrastructures,
connecting the service providers to the access network
ETSI
8 ETSI ES 282 001 V3.4.1 (2009-09)
functional entity: entity that comprises a specific set of functions at a given location
NOTE: Functional entities are logical concepts, grouping of functional entities are used to describe practical
physical realizations.
user equipment: one or more devices allowing a user to access services delivered by TISPAN NGN networks
NOTE: This includes devices when under user control commonly referred to as IAD, ATA, RGW, TE, etc., UE
does not include network controlled entities such as network terminations and access gateways.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3GPP Third Generation Project Partnership
AMF Access Management Function
A-MGF Access Media Gateway Function
AN Access Node
ARF Access Relay Function
AS Application Server
ASF Application Server Function
ASN GW Access Service Network GateWay
ATA Analogue Terminal Adaptor
AUC AUthentication Centre
BGF Border Gateway Function
BGW Border GateWay
BNG Broadband Network Gateway
BRAS Broadband Remote Access Server
BS Base Station
BTF Basic Transport Function
C-BGF Core Border Gateway Function
CND Customer Network Device
CNG Customer Network Gateway
CPN Customer Premises Network
CSCF Call Session Control Function
DHCP Dynamic Host Configuration Protocol
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Multiplexer
ECF Elementary Control Function
EFF Elementary Forwarding Function
ENUM tElephone NUmber Mapping
GPON Gigabit-capable Passive Optical Network
HLR Home Location Register
HSS Home Subscriber Server
IAD Integrated Access Device
IBCF Interconnection Border Control Function
I-BGF Interconnection-Border Gateway Function
I-CSCF Interrogating-Call Session Control Function
IGMP Internet Group Management Protocol
IMS IP Multimedia Subsystem
IMS-MGW IMS-Media GateWay
IP Internet Protocol
ISDN Integrated Services Digital Network
ISUP ISDN User Part
IVR Interactive Voice Response
IWF InterWorking Function
MAC Media Access Control (layer)
MGCF Media Gateway Control Function
MGF Media Gateway Function
MLD Multicast Listener Discovery
MPLS MultiProtocol Label Switching
MRFP Multimedia Resource Function Processor
ETSI
9 ETSI ES 282 001 V3.4.1 (2009-09)
MTP Message Transfer Part
NAPT Network Address and Port Translation
NAPT-PT NAPT and Protocol Translation
NASS Network Attachment SubSystem
NAT Network Address Translation
NGCN Next Generation Corporate Networks
NGN Next Generation Network
NNI Network to Network Interface
OLT Optical Line Termination
ONT Optical Network Termination
ONU Optical Network Unit
OSA Open Service Access
PES PSTN/ISDN Emulation Subsystem
PHY PHYsical (layer)
PIM Protocol Independent Multicast
PPP Point-to-Point Protocol
PSTN Public Switched Telephony Network
PUC Prevention of Unsolicited Communication
RACS Resource and Admission Control Subsystem
RADIUS Remote Access Dial In User Service
RCEF Resource Control Enforcement Function
RGW Residential GateWay
R-MGF Residential Media Gateway Function
SCCP Signalling Connection Control Part
SCTP Stream Control Transmission Protocol
SGCF Signalling Gateway Control Function
SGF Signalling Gateway Function
SGW Signalling GateWay
SIP Session Initiation Protocol
SLF Subscription Locator Function
TDM Time Division Multiplexing
TE Terminal Equipment
TF Transport Function
TGCF Trunking GateWay Control Function
TGW Trunking GateWay
T-MGF Trunking-Media Gateway Function
TVRA Threat Vulnerability and Risk Analysis
UE User Equipment
UPSF User Profile Server Function
WiMAX Worldwide Interoperability for Microwave Access
4 Overall architecture
The NGN functional architecture described in the present document complies with the ITU-T general reference model
for next generation networks [2] and is structured according to a service layer and an IP-based transport layer.
The service layer comprises the following components:
• the core IP Multimedia Subsystem (IMS);
• the PSTN/ISDN Emulation Subsystem (PES);
• other multimedia subsystems (e.g. IPTV Dedicated Subsystem) and applications;
• common components (i.e. used by several subsystems) such as those required for accessing applications,
charging functions, user profile management, security management, routing data bases (e.g. ENUM), etc.
This subsystem-oriented architecture enables the addition of new subsystems over the time to cover new demands and
service classes. It also provides the ability to import (and adapt) subsystems defined by other standardization bodies.
ETSI
Other networks
User Equipment
10 ETSI ES 282 001 V3.4.1 (2009-09)
IP-connectivity is provided to NGN user equipment by the transport layer, under the control of the Network Attachment
SubSystem (NASS) and the Resource and Admission Control Subsystem (RACS). These subsystems hide the transport
technology used in access and core networks below the IP layer.
The architecture described in the present document and related subsystems specifications is a functional architecture.
Each subsystem is specified as a set of functional entities and related interfaces. As a result implementers may choose to
combine functional entities where this makes sense in the context of the business models, services and capabilities
being supported. Where functional entities are combined the interface between them is internal, is hidden and
un-testable.
Figure 1 provides an overview of the NGN architecture. An example of realization of this functional architecture, with
an xDSL-based access network is provided in annex A. An example of realization of this functional architecture, with a
WiMAX-based access network is provided in annex B.
Applications
Service Layer
Other
Subsyst ems
User
profiles
Core IMS
PSTN/ISDN
Emulat ion
Subsyst em
Transport Layer
Network
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
Transport processing functions

Figure 1: TISPAN NGN overall architecture
The functional entities that make up a subsystem may be distributed over network/service provider domains (see
figure 2). The network attachment subsystem may be distributed between a visited and a home network. Service-layer
subsystems that support nomadism may also be distributed between a visited and a home network.
Visited Network Home Network
Distributed Subsystem
Core Network Core Network
(control) (control)
UE
Access
Core Core
Network Networks Networks
(transfer) (transfer) (transfer)

Figure 2: Distributed subsystems
This architecture supports the service capabilities and requirements identified in TS 181 005 [14].
An access network comprises an access segment and an aggregation segment (figure 2a). The access segment (also
known as "last mile segment" stretches from the customer premises to the first network node (also known as the "access
node"). The aggregation segment comprises the transport network elements enabling one or more access nodes to be
connected to a core network through an IP Edge Router, at the Di reference point.
ETSI
11 ETSI ES 282 001 V3.4.1 (2009-09)
NOTE 1: In configurations where the access segment uses the DSL technology, the aggregation segment generally
uses ATM or Giga Ethernet. The IP Edge is known as a Broadband Remote Access Server (BRAS) or
Broadband Network Gateway (BNG) and the access node is a DSLAM.
NOTE 2: In configurations where the access segment uses the GPON technology, the aggregation segment uses
Giga Ethernet. The IP Edge is known as a Broadband Network Gateway (BNG) and the functions of the
access node are distributed between the Optical Line Termination (OLT) and the Optical Network
Unit (ONU)/Optical Network Termination (ONT).
Access
IP-Edge
Transport Network Elements
Node
Di
Access Segment Aggregation Segment

Figure 2a: Access and aggregation segments
5 Transport layer
The transport layer comprises a transport control sublayer on top of transport processing functions in the access and
core networks. Equivalent functionality in the User Equipment (UE) is defined in clause 8.
The transport control sublayer is further divided in two subsystems:
• the Network Attachment SubSystem (NASS);
• the Resource and Admission Control Subsystem (RACS).
5.1 Transport control sublayer
5.1.1 Network Attachment SubSystem (NASS)
The Network Attachment Subsystem provides the following functionalities:
• dynamic provision of IP addresses and other terminal configuration parameters;
• authentication taking place at the IP layer, prior or during the address allocation procedure;
• authorization of network access based on user profiles;
• access network configuration based on user profiles;
• location management taking place at the IP layer.
The NGN architecture does not mandate a single NASS instance to support multiple access networks. This does not
prevent operators from deploying NASS functions that are common to multiple access networks (e.g. one user profile
database common to different access networks).
NOTE: The user profiles mentioned above are related to the access subscription only.
ETSI
User
Equipment
Core Network
User Equipment
12 ETSI ES 282 001 V3.4.1 (2009-09)
The NASS interfaces with the following entities (see figure 2b):
• the user equipment at the e3 reference point for configuration purposes;
• transport processing entities acting as relays to/from the user equipment for address allocation, authentication
and authorization purposes (a1 and a3 reference points);
• the Resource and Admission Control Subsystem at the e4 reference point for exporting subscriber access
profile information;
• service-control subsystems and applications in the service layer at the e2 reference point for exporting
information on access sessions and supporting notification services.
Applications
Service Layer
….
User
profiles
…
Service
Cont rol
Subsyst ems
e2
Transport Layer
e3 Network
e4
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
a1,a3
Transport processing functions

Figure 2b: NASS external reference points
Further details about the functionalities and architecture of the NASS can be found in ES 282 004 [5].
5.1.2 Resource and Admission Control Subsystem (RACS)
RACS is the TISPAN NGN subsystem responsible for the implementation of procedures and mechanisms handling
policy-based resource reservation and admission control for both unicast and multicast traffic in access networks, core
networks and customer premises networks.
Besides acting as a resource control framework, RACS also includes support for controlling Network Address and Port
Translation (NAPT) at the edge of networks and assisting in remote NAT traversal. Furthermore, RACS also covers
aspects related to the setting and modification of traffic policies, end to end quality of service and transport-level
charging.
The RACS interfaces with transport processing functions at the Re and Ia reference points and with the following
subsystems (see figure 2c):
• The Network Attachment Subsystem at the e4 reference point for obtaining subscriber access profile
information.
• Service-control subsystems and applications in the service layer at the Gq' reference point for exposing the
services it provides.
ETSI
User Equipment
13 ETSI ES 282 001 V3.4.1 (2009-09)
Applications
Service Layer
….
User
profiles
…
Service
Cont rol
Subsyst ems
Gq'
Transport Layer
Gq'
Network
e4
Attachment
Resource and
Subsyst em
Admission Control
Subsyst em
Re Ia
Transport processing functions
Transport Processing Functions

Figure 2c: RACS external reference points
Further details about the functionalities and architecture of the RACS are defined in ES 282 003 [6].
5.2 Transport processing functions
Transport processing functions in the access and core networks include basic elementary functions supporting packet
forwarding and routing, and more specific group of functions defined as functional entities.
These are:
• Media Gateway Function (MGF).
• Border Gateway Function (BGF).
• Resource Control Enforcement Function (RCEF).
• Access Relay Function (ARF).
• Signalling Gateway Function (SGF).
• Multimedia Resource Function Processor (MRFP).
• Access Management Function (AMF).
• Basic Transport Function (BTF).
Figure 3 provides an overview of the transport processing functions and their relationships to the other components of
the architecture.
ETSI
Other networks
User Equipment
14 ETSI ES 282 001 V3.4.1 (2009-09)
Service Layer
Transport control functions
RACS
NASS
Z, S/T
A-MGF
SGF
MRFP
T-MGF
e1 e1 Di
ARF AMF
Ds
RCEF C-BGF
I-BGF
BTF
Dj Di Ds
Iz
Transport processing functions

Figure 3: Transport processing functions overview
5.2.1 Border Gateway Function (BGF)
A Border Gateway Function (BGF) provides the interface between two IP-transport domains. It may reside at the
boundary between an access network and the customer premises equipment, between an access network and a core
network or between two core networks. It encompasses the functionality of a Resource Control Enforcement Function
(RCEF) defined in clause 5.2.1A and may also support one or more of the following elementary functions:
• usage metering;
• allocation and translation of IP addresses and port numbers (NAPT);
• interworking between IPv4 and IPv6 networks (NAPT-PT);
• assistance in hosted NAT traversal; and
• transcoding (see notes 1 and 2).
NOTE 1: The BGF is not the only place in the architecture where transcoding may be performed: MRFPs can also
perform transcoding.
NOTE 2: To support this function a BGF needs to be media aware.
A BGF may interact with entities in the transport control sublayer for the purpose of controlling one or more of the
functionalities it implements.
The present document identifies two main types of BGF:
• the Core BGF (C-BGF) that sits at the boundary between an access network and a core network, at the core
network side;
• the Interconnection BGF (I-BGF) that sits at the boundary between two core networks.
The C-BGF interfaces access networks at the Di reference point and other transport processing functions of the core
network at the Ds reference point.
The I-BGF interfaces other core networks at the Iz reference point and other transport processing functions of the core
network at the Ds reference point.
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15 ETSI ES 282 001 V3.4.1 (2009-09)
Each BGF instance implements different subsets of the functionalities identified for a generic BGF, depending on their
location and network operators' policies.
C-BGF I-BGF
Access Network Other Transport Processing Functions
Di Ds Ds Iz
Core Network
Figure 3a: Border Gateway Control Functions
Further details are available in the RACS specification ES 282 003 [6].
NOTE 3: The C-BGF and the I-BGF encompass, respectively, the functionality of the IMS Access Gateway and of
the Translation Gateway defined in TS 123 228 [4].
5.2.1A Resource Control Enforcement Function (RCEF)
A Resource Control Enforcement Function (RCEF) is a transport processing functional entity that supports one or more
of the following elementary functions:
• opening and closing gates (i.e. packets filtering depending on "IP address/port");
• packet marking for outgoing traffic;
• policing of incoming traffic;
• resource allocation for upstream and downstream traffic.
An RCEF can reside in any transport segment (i.e. access, aggregation, or core) or at its edges. Multiple RCEF
instances may exist in the same transport segment.
A RCEF may interact with entities in the RACS for the purpose of controlling one or more of the elementary functions
it implements (see ES 282 003 [6] for more details). It can receive/send information flows from/to a BTF and handle
corresponding requests/answers to/from the RACS.
5.2.2 Void
5.2.3 Access Relay Function (ARF)
The Access Relay Function (ARF) acts as a relay between the user equipment and the Network Attachment
SubSystem (NASS). It receives network access requests from the user equipment and forwards them to the NASS.
Before forwarding a request, the ARF may also insert local configuration information.
NOTE: When using PPP, the ARF may act as a PPPoE relay. When using DHCP, the ARF acts as a DHCP Relay
Agent.
5.2.4 Media Gateway Function (MGF)
A Media Gateway Function (MGF) provides the media mapping and/or transcoding functions between an IP-transport
domain and switched circuit network facilities (trunks, loops). It may also perform media conferencing and send tones
and announcements.
The present document identifies two types of MGF that may exist in the operator's network:
• the Access MGF (A-MGF) that connects legacy access types (e.g. analogue or ISDN) to the NGN;
• the Trunking MGF (T-MGF) that sits at the boundary between an IP core network and a Circuit-Switched
network.
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NOTE 1: An MGF may also be embedded in the user equipment (see clause 8). This type of MGF is known as a
Residential MGF (R-MGF).
NOTE 2: The T-MGF functional entity is identical to the IMS-MGW defined in TS 123 002 [3], although a
network node implementing this functional entity in an NGN network and a network node implementing
it in a 3GPP network may differ in terms of supported resources (e.g. codecs) and configuration.
5.2.5 Multimedia Resource Function Processor (MRFP)
A Multimedia Resource Function Processor (MRFP) provides specialized resource processing functions beyond those
available in media gateway functions. This includes resources for supporting multimedia conferences, sourcing
multimedia announcements, implementing IVR capabilities and media content analysis.
NOTE: This functional entity is identical to the MRFP defined in TS 123 002 [3], although a network node
implementing this functional entity in an NGN network and a network node implementing it in a 3GPP
network may differ in terms of supported resources and configuration.
5.2.6 Signalling Gateway Function (SGF)
The Signalling Gateway Function (SGF) performs the signalling conversion (both ways) at transport level between the
SS7 based transport of signalling and IP based signalling transport. The functionality of the SGF encompasses:
• reliable transport of SS7 upper layer signalling over IP, using SCTP procedures [1];
• SS7 firewall functionality - as far as applicable - by screening within MTP and SCCP headers.
NOTE: This functional entity is identical to the SGW defined in TS 123 002 [3], although a network node
implementing this functional entity in an NGN network and a network node implementing it in a 3GPP
network may differ in terms of configuration.
5.2.7 Access Management Function (AMF)
The Access Management Function (AMF) translates network access requests issued by the UE into a format that can be
understood by the NASS.
NOTE: In case PPP is applied, the AMF terminates the PPP connection and provides the inter-working with the
interface to the network attachment subsystem e.g. using an AAA protocol (RADIUS or Diameter).
5.2.8 Basic Transport Function (BTF)
All transport segments comprise one or more basic transport functions (BTF) which contain two elementary transport
processing functions: Elementary Forwarding Functions (EFF) and Elementary Control Functions (ECF). Physical
network elements (e.g. a bridge, a router etc.) - typically contain a BTF and might contain additional functional entities,
e.g. RCEF.
Figure 3b shows the BTF, the elementary functions comprising the BTF as well as the relation to other functional
entities of the NGN. Reference points BTF-BTF, RCEF-BTF, and BGF-BTF are outside the scope of the current
TISPAN Release due to their implementation specific nature and the fact that some of which are typically internal to a
device.
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RACS
Re Ia
Dj Di Di,Ds Ds,Iz
RCEF BGF
EFF ECF
BTF
Figure 3b: Transport Function (TF) in the context of other functional entities of the NGN
5.2.8.1 Elementary Forwarding Function (EFF)
An Elementary Forwarding Function (EFF) forwards traffic data received on one flow point "In-FP" (flow point is used
here similar to ITU-T Recommendation G.8010 [15]) to one or more flow point(s) "Out-FP(i)", i = 0.n of a transport
element; where "In-FP" is not contained within the set of "Out-FP(i), i = 0.n". Consequently, for a unicast type of
operation there is exactly one Out-FP (i.e. i = 1), while for multicast type of operation the set of "Out-FP(i)" can contain
any number of flow points (including the case where "Out-FP(i)" equals the empty set).
5.2.8.2 Elementary Control Function (ECF)
An Elementary Control Function (ECF) processes control protocol data for unicast (e.g. path-coupled signalling as well
as multicast data (e.g. routing protocol) received on one flow point. As a result of this processing, the ECF might decide
to:
• send control protocol data (including events to trigger policy evaluation) to other ECF;
• interact with one or more EFF to establish new or modify existing forwarding behaviour of the EFF;
• interact with one or more instances of RCEF and/or BGF. This includes the ability to create events to trigger
policy evaluation in RCEF and/or BGF.
ECF may also receive requests from RCEF to perform policy enforcement (e.g. trigger transport control protocol
actions) and reply back to RCEF indicating the result of the requested operation.
6 Service Layer Model
6.1 The "Core" IP Multimedia Subsystem (IMS)
The IP Multimedia Subsystem (IMS) core component of the NGN architecture (Core IMS) supports the provision of
SIP-based multimedia services to NGN terminals. It also supports the provision of PSTN/ISDN simulation services.
NOTE: The "Core IMS" is a subset of the 3GPP IMS defined in TS 123 002 [3] which is restricted to the session
control functionalities. Application Servers (AS) and transport/media related functions such as the
Multimedia Resource Function Processors (MRFP) and the IMS Media GateWay function (IMS-MGW)
are considered to be outside the "Core IMS".
The architecture of this subsystem is further described in ES 282 007 [7].
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6.2 The PSTN/ISDN Emulation subsystem (P
...