ITU Workshop on
“Standardization on IMT, M2M, IoT,
Cloud Computing and SDN”
(Algiers, Algeria, 8 September 2013)
Migration from legacy
networks to NGN
Chaesub Lee
Contents
1. Legacy Networks (LNs)
2. Summary of NGN
3. Gaps
4. For Migration
5. Conclusion
2
1. Legacy Networks (LNs)
Definition and scope of LNs
 Definition of LNs (Not formal):
a network based on older, out-dated protocol
that is not based on the IP (TCP/IP) protocol.
IPX, SNA, AppleTalk and DECnet are examples
of legacy networks.
 Scope of LNs:
• Public Switched Telephone Networks (PSTN)
• Packet Switched Data Networks (PSDN)
• Integrated Services Digital Networks (ISDN)
3
1. Legacy Networks (LNs)
PSTN
 Features of PSTN:
• the oldest and widest popular network
• voice-band services (voice and 3.1 kHz
Audio-band data services)
• the channel remains reserved and not allow
to use for competing users (full dedicated)
• provides continuous transfer without the
overhead
• a dedicated path persisting between two
communicating parties or nodes
• the constant bit delay during a connection
• guaranteed a QoS of the circuit (channel), so
no degradation of QoS by competing users
4
1. Legacy Networks (LNs)
PSTN
 Architectures and Configurations of PSTN
Local Switch
Toll Networks
3
Local Switch
Tandem Networks
Toll Switch
Local Switch
4
4
1
Local Switch
Local networks
Tandem
Switch
2
5
International
Gateway
Satellite
International Cable
(Optic, submarine)
5
1. Legacy Networks (LNs)
 Features of PSDN:
PSDN
• Packet means a small container or a pouch, such as a
formatted block of data
• Physical layer: specifies the physical, electrical,
functional and procedural characteristics to control the
physical link between a DTE and a DCE (e.g. X.21)
• Data link layer: link access
procedure for data interchange
on the link between a DTE
and a DCE (LAPB)
that manages a
communication session
and controls the packet
framing including error
correction & orderly delivery
• Packet layer: exchanging
control and user data
packets to form a
packet-switching network
6
1. Legacy Networks (LNs)
ISDN
 Features of ISDN:
• Circuit switching: Provide 64 kb/s including
bigger than 64 kb/s (rate adapted to 64 kb/s
for less than 64 kb/s rate)
• Packet switching: Provide number of packet
mode bearer services based on two types;
 packet handling functions: handling of
packet calls within the ISDN;
 interworking functions: interworking
between ISDN and PSDN;
• Frame mode: Provide the order preserving
bidirectional transfer of service data units (L2
frames) on the basis of an attached label
• Signalling capability: carried by the Dchannel
7
1. Legacy Networks (LNs)
ISDN
 Functional architecture of ISDN
Broad
-band
Leased
Line
PSTN
PSDN
8
1. Legacy Networks (LNs)
ISDN
 Functional configuration of ISDN
9
2. Summary of NGN
Definition of NGN
ITU-T
Rec.
Y.2001
Next Generation Network (NGN):
a packet-based network able to provide
telecommunication services and able to
make use of multiple broadband, QoSenabled transport technologies and in
which service-related functions are
independent from underlying
transport-related technologies.
It enables unfettered access for users to
networks and to competing service
providers and/or services of their choice.
It supports generalized mobility which
will allow consistent and ubiquitous
provision of services to users.
2. Summary of NGN
Practical meaning of NGN
NGN is a Broadband Managed IP-based
Network
• NGN got benefits from today’s broadband
capabilities; over fixed, over mobile and over
wireless
• NGN has capabilities to support managed
features of IP based network, especially QoS,
Security and Mobility
Best Effort
IP
Limited BW
N
G
N
Managed IP (Quality, Security, Mobility)
Broadband: Fixed, Mobile, Wireless
2. Summary of NGN
Summary features of NGN
Packet-based transfer;
Separation of control functions;
Decoupling of service provision from transport;
Support for a wide range of services based on service
building blocks;
 Broadband capabilities with end-to-end QoS;
 Interworking with legacy networks via open interfaces;
 Generalized mobility;
 Unfettered access by users to different service providers;
 A variety of identification schemes;
 Converged services between fixed/mobile;
 Support of multiple last mile technologies;
 Compliant with all regulatory requirements
(e.g. emergency, privacy, lawful interception, etc.)




2. Summary of NGN
Capability requirements of NGN (1)
 Transport connectivity
 Use of IPv4 and Ipv6;
 real time and non-real time comm.
 One-to-one and one-to-many connectivity
 Communication modes
 One-to-one, one-to-many;
 Many-to-any, many-to-one
 Media resources management
 Support various media resources and its
managements;
 Media recording, DTMF/advanced speech recognition,
media conversion, transcoding, bridging, duplication
and insertion
 Codecs
 Transcoding should be avoided wherever possible;
 Shall support end-end codec negotiation;
 Supporting G.711 for interworking with other networks
2. Summary of NGN
Capability requirements of NGN (2)
 Access network and network attachment




Shall support diverse access transport technologies;
Capable of providing IP connectivity;
Support registration & re-config. at the access network;
User access authen. data/inf. in user profile used for
access configuration
 User networks
 support access to the NGN via a user network with
NAT/NAPT/Firewalls;
 simultaneous use of multiple types of access transport
functions by a single terminal
 Interconnection and Interworking
 Connectivity-oriented and service-oriented
interconnection;
 support interworking with PSTN/ISDN and other networks
2. Summary of NGN
NGN Basic Reference Model
 Separation Transport (Access and Core) from Services
 But keeping 3 Planes for basic function: User, Control
and Management
Management Plane
Control Plane
User Plane
NGN Service Layer
Management Plane
Control Plane
User Plane
NGN Transport Layer
2. Summary of NGN
Overall NGN Architecture
Applications
ANI
SNI
Application Support Functions
and Service Support Functions
IdM
Functions
Service Control and Content Delivery Functions
Management Functions
Service User
Profiles
Service
Control Functions
Functions
from other
Service
Providers
Content Delivery Functions
Service Stratum
Network Attachment
and Control Functions
Transport User
Profiles
Mobility
Management
and Control
Functions
Resource
and
Admission
control
Functions
Functions
from
Other
Networks
Transport Control Functions
End-User
Functions
Transport Functions
UNI
Y.2291
NNI
Transport Stratum
Control
Media
Management
IdM
3. Gaps
Technical Gaps between NGN and LNs
Legacy Networks
Service
Switching
PSTN
PSDN
internet
Voice &
Voiceband Data
(telephony)
(Non Real-time)
Data
Information
Circuit
Packet
Packet
(X.25)
(IP)
PDH
(SDH)
PDH
(SDH)
PDH
(SDH)
Narrowband
(Copper)
Narrowband
(Copper)
Narrow and
Broadband
(64kbit Channel)
Transmission
Medium
Technical Gaps
PSTN
PSDN
internet
Voice &
Voiceband Data
(telephony)
Data
(Non Real-time)
Information
Circuit
Packet
Packet
(64kbit Channel)
(X.25)
(IP)
NGN
Integrated Multimedia
Services (real/non real-time)
IP
QoS/Security
Packet adaptation/Addressing/Accounting
PAD/Numbering/Accounting & charging/Echo Cancellation
3. Gaps
Gaps on Architectural aspects
Vertical
views
Single-layered
TRANSIT NETWORK
NATIONAL/REGIONAL
NGN
Horizontal
views
LAYER
LEX/GW
LAYER
RU
LAYER
4. For Migration
PSTN/ISDN Emulation & Simulation
 Emulation: Provision of PSTN/ISDN service
capabilities and interfaces using adaptation to
an IP infrastructure
 An encapsulation process
 All services available to PSTN/ISDN users
 User experience not changed
UNI
UNI
ADF2
User
equipment
* ADF: Adaptation Function
NGN
ADF2
User
equipment
4. For Migration
PSTN/ISDN Emulation & Simulation
 Simulation: Provision of PSTN/ISDN-like service
capabilities using session control over IP
 PSTN/ISDN-like services available
 Availability of possible new services
 User experience is changed by the network
transformation
UNI
UNI
NGN
User
equipment
User
equipment
UNI
ADF1
Legacy User
equipment
4. For Migration
Overall Configuration
Simulation
NGN
(Carrier Y)
PLMN
User equipment
User equipment
NNI
IWF
UNI
UNI
ADF1
NGN
(Carrier X)
UNI
User equipment
ADF1
ADF2
ADF2
UNI
IWF
IWF
User equipment
NNI
PSTN/ISDN
Public IP
Network, e.g.
SIP (non-IMS)
User equipment
UNI = User Network Interface = IF1
NNI = Network Node Interface = IF2
User equipment
Emulation
ADF= Adaptation Function
IWF=Interworking Function
4. For Migration
Overlay Migration Scenario
 deploy NGN overlay to the existing LNs
 two infrastructures both NGN and LNs exist together
 NGN provides advanced services while LNs keep
existing services
Overlay NGN network
ADF
NGNNGN
expansion
NGN
NGN
ADF
ADF
IWF
Legacy
Networks
shrink
Legacy
Networks
4. For Migration
Replacement Migration Scenario
 Use mixed simulation and emulation together
 Simulation: for PSTN/ISDN-like services to the NGN users
with advanced NGN features
 Emulation: for voice oriented services keeping the legacy
terminal
Overlay
NGN network
NGN
Core
ADF
ADF
NGN-A
(Simul.)
ADF
IWF
NGN-A
Legacy
Replace
(Emul.)
Networks
Legacy
Core
Replace
LegacyAccess
LegacyAccess
LegacyAccess
LegacyAccess
5. Conclusion
 Handbook on “Migration Scenarios
from Legacy Networks to NGN in
developing countries” has been
approved at the February 2013 SG13
meeting
Thank you for your
attention !!!