IP networking & MEDIACOM-2004
ITU Workshop
« IP networks towards NGN »
Geneva, 24-27 April 2001
(Edition 2 du 18 04 01)
Gaël Fromentoux
Renaud Moignard
Christine Pageot-Millet
André Tarridec
FT R&D/DAC
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Outline
Introduction
Proposed definitions
IP services & network current state
VoIP
Control plane architecture & QoS
Mobility & nomadism
IPv6 migration.
Conclusion
References & Glossary
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Introduction
 In this paper, it is first proposed a set of definitions to characterise NGN solutions
& in particular a so-called " target NGN ".
 It is then applied to the services and network evolution of an IP domestic network
whose final state would be compliant with the proposed " target NGN ".
 Important matters related to this evolution are briefly evoked :
 IP services & network current state,
 control plane architecture & QoS,
 VoIP,
 Mobility & nomadism ,
 IPv6 migration.
 As a conclusion, possible synergies between IP, mobile and telephony networks
evolution towards NGN are pointed out.
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Proposed definitions : NGN
 A set of definitions based upon functional architecture principles
 Proposals aim at helping to provide a common understanding and vocabulary related to NGN matters.
 NGN solutions are characterised by the following main attributes:
 A services control layer independent from the bearer resources,
 A network service layer in packet mode (ATM, IP...),
 Open and better standardised interfaces, between the services control & the resources control,
 The externalisation of part of the control functions with regards to the transfer layer.
 The expected advantages from architectures compliant with those principles are :
 The set up of a business model on line with the fast moving telecommunications environment
 The ability to support any kind of services & to make them evolve at their own pace,
 Architecture flexibility gained from the independence between services and bearer resources,
 Resources mutualisation stemming from the two preceding points,
 The use of any kind of transmission support (ADSL, SONET, SDH, WDM, radio...).
Note that some solutions are already labelled NGN ones although they do not respect the whole
set of rules proposed here.
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Proposed definitions : Target, Telephony & Data NGNs
 Definition : a NGN is a “ Target NGN " in
case
it
supports
all
kinds
of
telecommunications services and meets the
proposed NGN features.
 Definition : a NGN will be labelled
T elephony N G N
T eleléphonique
D ata N G N
T arget N G N
T elephony
services
téléphoniques
N on T elephony
services
“ Telephony NGN " when it is at least able to
support the whole set of existing telephony
services (plain, enhanced and IN services)
with matching Quality of Services, QoS.
 Definition : a NGN will be labelled “ Data
NGN ” when it is not able to support the
whole set of existing telephony services
(plain, enhanced and IN services) with
matching Quality of Services.
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A “ Target NGN ” includes services supported
by Telephony NGNs & those by Data NGNs.
 Target NGNs can be considered as
the final evolution of these two ones.
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Proposed definitions : Core & Transit NGNs
« transit NGN »
Control Platform :
Call Server, Gatekeeper,
Bandwidth broker,…
PSTN, ISDN
PSTN, ISDN
RSU
LEX
GW
GW
« core NGN »
LEX
RSU
 A « transit NGN » interconnects local
networks to packet network cores.
> great interest for inhomogeneous networks, for
migration, when traffics sources are scattered
etc …
NA
Concentrating
Multiplexing
Local
switching
Access
Edge
Long haul
switching
Core
 A « core NGN » covers core network part. It
interconnects edges & offers access to
international networks
Local
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Proposed definitions : Local NGN
Services Control Platform
or Local control Platform
(Call Server d’Appel,
Gatekeeper, Policy server,
Softswitch, MGC, …)
Services
Control
Platform
« Local NGN »
Local control
Platform
 A network solution will be labelled
a “ Local NGN ” when it covers
the access and edge network
parts.
 To support a large range of
NA
Concentrating
Multiplexing
Local
switching
Access
Edge
Long haul
switching
Core
services
 To collect various accesses of
different kind
Local
To emulate LEX functions is just not enough.
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IP services and network current state : IP
network
 IP networks provide best effort data services
> to residential customers, professional customers
& companies.
> Internet, Intranet and Extranet connectivity is possible.
End users
 Two main services
> aggregation services to collect the traffic of
Not always on customers to deliver it to IAPs/ISPs,
> transport services to convey the traffic of always
connected users between sites directly attached to
the IP network and towards Internet.
 Only best effort services based on the IPv4 protocols
are available.
> No service differentiation through differentiated
Service classes, no QoS guarantee.
Over provisioning is the remedy.
Not Always On
Always On
To Collect &
To Deliver
To Transport
IP network
Services
IAP/ISP
Voice services such as VoIP, Internet Call Waiting,
Centrex IP may be supplied
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IP network current state
 3 parts : access, edge and core.
The access part collects and concentrates customers
traffic through 2 Access Server types :
•
NAS for narrowband switched connections
•
BAS for broadband permanent connections.
2 kinds of NAS : data-oriented and voice-oriented NAS.
The edge part concentrates the traffic and performs
specific edge functions ( flow classification &
IP Network
conditioning, external routing protocols processing &
network-based VPN handling).
Edge and border routers support interfaces with the
access network, internal servers, ISPs/IAPs & Internet.
The core part routes and forwards aggregated flows
over core routers.
MPLS improves the traffic engineering and supports
network-based IP VPNs.
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IP network : NGN like features
 IP networks limitations :
> no QoS guarantees and no differentiated services as
required by some users and applications,
> no service control servers on top of the call servers for
value-added services,
> no service portability over different access networks,
 IP networks features consistent with NGN
features :
> no service portal.
> separation of transport resources from AAA servers and
call control,
> service portability over a given access network,
> use of a packet transport to support every service (data,
voice).
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VoIP (H.323 & SIP) general architecture
Management
VoIP : H323 (ITU) & SIP (IETF).
 The GK is the control platform.
Service
plane
SCP
SCP/IP
INAP
Application
server
API
INAP/IP
It controls end points (GW & terminal) of a
H.323 domain & performs call request
(call admission).
 GWs perform IP/PSTN inter-working
CCF
Gatekeeper
or Proxy SIP
SS7
SG
PSTN
LEX
H323
or SIP
H323
or SIP
IP
GW
for media stream
 SGs for
working.
SS7/IP
signaling
inter-
 Supplementary services services
could be performed within a SCP via
an INAP/IP interface or within an
application server via API or
proprietary interfaces.
IP
 VoIP can be considered as a “ Data NGN ”: MM services i.o telephony services. No absolute QoS is available.
 VoIP architectures may reach Target NGN by introducing QoS & telephony services. Mobility is still missing.
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Control plane architecture & QoS
SLA
ACCESS
QUALITY
1
CUSTOMER
USER
C
U
S
T
O
M
E
R
S
U
P
P
L
I
E
R
Control Plane: Services & Resources
SLA
SERVICES
SUPPLIER
SERVICES
CONTROL
USER
Transfer need
RESOURCES
SUPPLIER
 Services control: to analyze services
requests
independently
from
the
resources
RESOURCES
CONTROL
 Resources control: to select & monitor
resources after the request (routing &
path algorithms)
 Resources mediator to be found
QoS - NP
QoS
2
TRANSFER
QUALITY
T
RESOURCES
 QoS is an end-to-end issue, concerns every layer of the transfer
plane, requires coordinated mechanisms & procedures in the
transfer, control & management planes
 A full QoS support is very complex to implement
Its introduction will be progressive
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 It is a major requirement for the next
generation IP networks. Voice, videoconf
& streaming cannot cope with best effort.
Customers have differentiated needs
requiring differentiated QoS levels
 IP networks to support several QoS levels
absolute QoS, relative QoS and best
effort.
 Unlimited bandwidth is not ready yet
 The Integrated & Differentiated Services
models as first steps whereas MPLS is
under deployment
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NGN introduction in CS and PS domains – post R5
architecture.
2 domains : PS & CS in UMTS R5
SCP
Application
 An Internet Multimedia Subsystem
(IMS) is introduced. The PS domain
associated with the IMS allows UMTS
R5 to offer VoIP services
Application
servers
API
CAP
Network
Service
& Control
CSCF
HSS
MSCS &
SGSNS
GMSCS &
GSGSNS
 CSCF controls admission, incoming
calls and communicates with HSS,
(Home Subscriber Server), which is a
customer database dealing with
mobility and service profile
 MGCF controls gateways that perform
PSTN/IP
network
inter-working
between
MGCF
T-SGW
Transport
MM IP
MGW, GSN
UTRAN
PSTN
 3GPP2 is considering IP for the mobility management.
Mobile IP is a key component of "full IP" scenarios.
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 SIP protocol has been chosen by
3GPP for UMTS R5. From a strict
functional viewpoint, except for the
mobility aspect, a CSCF is a SIP
server
 Post R5 release proposes an
evolution of PS domain towards NGN:
externalization of some control
functions
in
SGSNserver
&
GGSNserver
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Mobile IP : architecture & principles
Home
Agent
NC
IP network
Home
subnetwork
Sub
network
3 main elements compose the
mobile IP architecture :
Mobile IP to manage macro-mobility Foreign
at the IP level. Mobile IP mainly allows: Agent
 communication hold-on when a
mobile moves from an IP sub-network
to another,
 the use of the same IP address
attached to a mobile and valid in all
IP networks.
Register
 Mobility function within the terminal to
perform moving detection function &
registration functions to a HA or a FA.
Visited
sub
network
 HA function in the router that
connects the H sub-network of the mobile
is in charge of updating the information
NM
DB for mobile location & reemitting to
data to its current location
 FA function in the router that connects
 As a conclusion IP network could both handle macro-mobility
the V sub-network of the mobile. It
(e.g. in target NGN and partly in UMTS networks) and telephony
services, thanks to respectively mobile IP and to SIP or H323
architectures.
registers visiting mobiles & offers services
such as datagrams routing to
visiting mobiles.
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VHE : a distributed user profile
 To trace a user to know its profile and how to recognize it : the Virtual Home Environment (VHE)
concept “ a system concept for personalized service portability across network boundaries and
between terminals ". ( ETSI 3GPP )
 These concept have been designed in the UMTS networks context : to allow users to always have a common
look and feel of their service. No difference for users while they roaming in other networks.
 VHE will be created by a combination of capabilities handled by service providers, network operators and
located within terminal equipments.
 The initial definitions still hold in a non UMTS context (a global service provider for a consistent view of its
customers being potentially mobile, fixed and Internet customers.
 With regards to this perspective global operators would gain to share a common understanding of :
The models that describe their customer (i.e. data attached to their customer),
The functions that allow services to be delivered to their customer (i.e. applications dealing with
customers),
The equipment running these applications and the associated databases.
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IPv6 : to fix IPv4 limitations
 IPv6 to meet the requirements for a large-scale worldwide deployment.
 IPv6 supports a number of enhanced features, such as :











larger unicast and multicast address space,
anycast address,
aggregatable addressing for hierarchical routing,
host address auto configuration,
easy site renumbering,
flow identification for QoS support,
streamlined packet formats for improved forwarding performance,
multicast support (explicit scope),
extension headers used for supplementary capabilities,
security providing packet authentication and encryption,
mobility improvement through auto configuration, security, anycast address and destination options.
 Given the large amount of IPv4 equipment currently deployed in public & private networks both protocols
will coexist for a long time.
 Several transition mechanisms have been incorporated in the IPv6 design to help with the migration phase.
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IP network towards a possible Target NGN
… lots of work ahead !
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Conclusion
 A variety of networks have been deployed more or less dedicated to a particular service.
 Most of the past technical constraints are no longer valid given the fast evolution in
architectures and broadband technologies (control/transfer plane evolution, xDSL,
UMTS, DWDM, packet transfer)
 Many legacy networks are evolving towards Next Generation Networks whose
architectures are based on the same principles.
 These new architectures will provide more flexibility for the support of services.
 To enable generalized multimedia mobile services customers should be provided with
personalized services across networks and between terminals, over mobile or fixed
accesses whatever their location is.
 This is the target.
 In this paper, technical issues to overcome have been more specifically addressed in the
case of IP transport. Special attention should be paid to fixed and mobile service
convergence.
 Many of these issues are currently under study in several standardization bodies and
fora, to make this attractive future happens they should be consistently dealt with.
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References
"A Next generation architecture for the public network " ISS2000
TINA-C Network Resource Architecture, version 3.0 – Feb. 1997
TIPHON Network Architecture & reference configurations, DTS 02003 v0.0.1 – ETSI – March 1999
Multiservice Switching Forum Architecture, MSF99.074 – March 1999
Megaco Protocol Proposal Working draft, draft-IETF- megaco-protocol-01.txt – April 1999
Draft ITU-T Recommendation Q.BICC, Bearer Independent Call Control protocol definition
RFC 2543 SIP : Session Initiation Protocol
RFC 3015 Megaco Protocol v1.0
RFC 2002 IP mobility Support (for Ipv4)
Universal Mobile Telecommunications System (UMTS); Virtual Home Environment (VHE) in the
Integrated Services Digital Network, Evolved UMTS core network, ETSI EG 201 717.
Universal Mobile Telecommunications System (UMTS); Service aspects; Virtual Home Environment
(VHE), ETSI TR122 970, 3G TR 22.970.
Eurescom Project P920, UMTS Network Aspects (http://www.eurescom.de/public/projects/P900series/p920/P920.htm
RFC 1633 Integrated Services in the Internet Architecture: an Overview
RFC 2475: An Architecture for Differentiated Services
RFC 3031: Multiprotocol Label Switching Architecture
draft-ietf-mpls-diff-te-reqts-00: Requirements for support of Diff-Serv-aware MPLS Traffic Engineering
RFC 1883: Internet Protocol Version 6 (IPv6)
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Glossary
ARF: Access to the Resources Function
ASF: Access to the Services Function
AP: Application Part
BAS: Broadband Access Server
CAP: Camel Application Part
CS: Call Server
CSCF: Call State Control Function
DWDM: Dense Wavelength Division Multiplexing
FA: Foreign Agent
GGSN: Gateway GPRS Support Node
GK: GateKeeper
HA: Home Agent
HSS: Home Subscriber Server
IAP: Internet Access Provider
IGP: Interior Gateway Protocol
INAP: Intelligent Network Application Part
ISDN: Integrated Services Digital Network
ISP: Internet Service Provider
LEX: Local EXchange
LSP: Label Switched Path
MG: Media Gateway
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MGC: Media Gateway Control
MGCF: Media Gateway Control Function
MPLS: MultiProtocol Label Switching
MSC: Mobile service Switching Center
NAS: Network Access Server
NGN: Next Generation Network
OTN : Optical Transport Network
PHB: Per-Hop Behaviour
POTS: Plain Old Telephone Service
PDSN : Packet Data Serving Node
PS: Proxy SIP
PSTN Public Switched Telephony Network
QoS : Quality of Service
RC: Resources Control
SC : Services Control
SGSN: Serving GPRS Support Node
SGW: Signalling Gateway
UMTS: Universal Mobile Telecommunications System
VHE: Virtual Home Environment
VPN: Virtual Private Network
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