NGN BASICS

Essential Features of Public Network
• Requirements
– QoS guarantee
– High availability
• Equipment hot-swappable hardware
• 99.999% availability
• On-line software upgrades
– Scalability
– Based on global (open) standards
– Support for a new range of applications

EXISTING NETWORKS
• PSTN:
• The network consists of Local exchange/RSU as a part of
Access Network and TAXs as a part of core Network.
Already huge amount of money has been invested in PSTN
setup
• CAPEX (Capital Expenditure) and OPEX (Operational
Expenditure)

PLMN (Public Land Mobile Network)
• PLMN has been developed to provide voice
services for wireless subscribers. Though in
recent times many applications has
emerged as killer application for mobile.
• PLMN includes BTS/BSC as access
network and MSC as a core Network

PSDN/PSPDN
• This network was basically designed for accessing remote
files and servers for defense people and universities but
nowadays nobody can think of living without data network
services.
• The basic and most popular application of data networks is
Internet. Other applications include E-commerce, online
banking, online gaming, E-shopping, IPTV Video on
demand and many more. Data network is an assembly of
routers, which are responsible for forwarding information
from one end to other

Drawbacks
• The separate network infrastructure and
no sharing of infrastructure among them.
• Sharing through Gateways
• Own service platforms in other words services are
tightly coupled with their networks
• Separate access transport and switching network
service provider has to invest in all the three
networks separately
• CAPEX (Capital Expenditure) and OPEX

Why NGN ?Why NGN ?
• Need to converge and optimise the operating networks and the
extraordinary expansion of digital traffic (i.e., increasing demand for
new multimedia services, increasing demand for mobility, etc.).
• • Slow to develop new features and capabilities.
• • Expensive upgrades and operating costs.
• • Proprietary vendor troubles
• • Large power and cooling requirements.
• • Limited migration strategy to New tech.
• • Model obsolescence.

NGN Vision
Next Generation Network is the framework where operator will
have a common transport network based on Internet Protocol for
providing all kinds of telecommunication services.
• Hence operators will have to install and maintain only a single
network, which will reduce its CAPEX and OPEX significantly.
• Moreover service provisioning will become easier because of the
introduction of new and intelligent servers.
• NGN is able to provide Vendor independence because of the
standard protocols it uses for interaction with network elements.

NGN Definition
• ITU-T definition for NGN:
– A Next Generation Network (NGN) is a packet-
based network able to provide services including
Telecommunication Services and able to make use
of multiple broadband, QoS-enabled transport
technologies and in which service-related
functions are independent from underlying
transport-related technologies.
– It offers unrestricted access by users to different
service providers.
– It supports generalized mobility which will allow
consistent and ubiquitous provision of services to
users

NGN – ITU Perspective
• Next Generation Network (NGN) provides a framework
for network evolution, as defined by the ITU-T (Rec.
Y.2001)
• Key Characteristics
– Packet-based network [generally Internet Protocol or IP]
– Independence of service-related functions from underlying
transport technologies
– Interworking with legacy networks via open interfaces
– Generalized mobility
– Unrestricted access by users to different services and/or
service providers

• ETSI (European Telecommunication
Standardisation Institute) defines the NGN as a
concept for defining and deploying networks, which
due to their formal separation into different layers
and planes and use of open interfaces, offers
service providers and operators a platform, which
can evolve in a step-by-step manner to create,
deploy and manage innovative services.
NGN Definition (ETSI)NGN Definition (ETSI)

Fundamental Aspects NGNFundamental Aspects NGN
• Packet-based transferPacket-based transfer
• Separation of control functions among bearer capabilities, call/session, andSeparation of control functions among bearer capabilities, call/session, and
application/serviceapplication/service
• Decoupling of service provision from transport, and provision of open interfacesDecoupling of service provision from transport, and provision of open interfaces
• Support for a wide range of services, applications and mechanisms based onSupport for a wide range of services, applications and mechanisms based on
serviceservice
building blocks (including real time/streaming/non-real time services andbuilding blocks (including real time/streaming/non-real time services and
multimedia)multimedia)
• Broadband capabilities with end-to-end QoS and transparencyBroadband capabilities with end-to-end QoS and transparency
• Interworking with legacy networks via open interfacesInterworking with legacy networks via open interfaces
• Generalised mobilityGeneralised mobility

NGN Architecture
• NGN Concept
– A unified packet transport layer for all types of services
– A session based control architecture
• For user to user voice , video and data services over the packet
infrastructure
– A common Service delivery platform
• Expectations from NGN
– Generate new revenue streams by having fast roll out of
new multimedia services
– Secure voice revenue stream by integrating PSTN
infrastructure with NGN
– Provide solution to cater to PSTN obsolescence wherever
applicable

Requirements for NGN Implementation
• Equipment and Network Interoperability between various
Operators
– A standards based functional architecture
– Standard interfaces and protocols
• Ability to serve Fixed (Copper and fibre), Wireless and
Mobile Networks
• Open Services Architecture
– Standard interfaces open to third party application service
providers
• QoS Control Mechanism
– Important for voice and video services
– Requires bandwidth allocation mechanism at access level
as it is shared between various services

Requirements for NGN Implementation
• Need to share management functions like
provisioning, metering, billing, QoS monitoring
• Provide Generalized Mobility features
– Mobility features at the fixed access, nomadism
– Provide service continuity between fixed and mobile
access leading to convergence
• Common technology for transport layer
– IP/MPLS has emerged as the most suitable
technology for this layer

NGN Concept
PSTN
PLMN
PSPDN
Service / Application Layer
Control Layer
Transport Layer
Access Layer
Each vertical on the left has to be split into Network
Elements that map onto each horizontal on the right

NGN Architecture
NGN is a layered architecture consisting of transport, access, control and application
layer. It is important to note that all the layers are independent from each other.
Change in one layer should not affect other layers

Interfaces
Switching
Call Control
Call Server /
Soft Switch
Routers of
IP/MPLS
Network
Gateways
PSTN
Switch
NGN Components
PSTN to NGN Mapping
TDM
Transport
Network
Common IP MPLS Transport
SG / TMG /
LAG

Service X Service Y
Separated control
NB Wireless
BB Wireless
BB Wireline
IP/MPLS Transport Core
Management
Service Layer
Control Layer
Access Layer
Open interfaces
SIP
H.248 QoS Mechanism
FMC
Usage Measurement

NGN Concept
Service / Application Layer
Application Layer
Transport Layer
Access Layer
NGN
PSTNPLMN

Access Layer
• Access Layers is responsible for direct subscriber
attachment function.
• NGN can support all kind of existing access as well
as upcoming access and is capable of processing
traffic originated from PSTN, GSM, CDMA, xDSL,
WiMAX or any other access system.
• Depending upon the type of access, protocol
conversion and/or media conversion may be
required at the NGN Gateways

NGN Gateways
•Media Gateway:
•Access gateway
•Signaling gateway.

Media Gateway
• Terminates media, coming from PSTN/PLMN in E1 / STM. Here it
is responsible for packetisation of media under the instruction of
control layer
• supports packetized voice and the interface to whatever medium the
voice is to be transported on.
• The MG performs the task of packetizing voice and providing
connections from switched circuits (TDM) to packetized circuits (IP,
Frame Relay, or ATM).
• It is responsible for media conversion, resource allocation and
resource management, and event notifications.

Media Gateway
• It is responsible for reporting events to the media gateway controller
(MGC) within its zone.
• Between Media Gateways (MGs) and Media Gateway Controllers
(MGCs) the protocol used is Megaco/H.248.
• RTP protocol is used between two MGs for packetized bearer traffic.
• The purpose of this protocol is to provide communications for call
control and call signaling.

Functions of Media Gateway:
• Media Conversion: conversion from TDM circuit-switched
connections to ATM, IP, or Frame Relay connections
• Resource Allocation: Resource allocation includes the
reservation and release of all resources , under the direction of the
MGC
• Event Notification: maintain the state of all resources and report the
state to the MGC.
• If a particular resource fails, the MG reports the failure to the MGC.
• The MGC maintains a state table for all resources within the MGs in
its zone.

Signaling gateway
• It is a bridge to the PSTN
• It converts between SS7 addresses (point codes)
and IP addresses
• SIGTRAN architecture is used between Sig Gate
Way and Media Gateway Controller.

Transport Layer
• Transport Layer of NGN is based on IP.
• Transport Layer forms the core of the Network.
• It basically consists of Routers, which are responsible for carrying
traffic originated by access layer.
• it should be able to make use of bandwidth policies and QoS policies.
Operator has to think of managed Network for its subscribers.
• It is basically an assembly of routers connected with optical network.
• Traffic coming from gateways is properly routed by those routers

Softswitch (Media gateway controller):
• The MGC is responsible for controlling all the MGs within its
zone.
• performs a number of call control functions that are typically
found in the call control portion of a legacy switch.
• This includes determining and controlling signals used on specific
circuits, such as ringing and busy tones.
• The MGC also determines the QoS required for any one
connection at the MG.
• In short, the call handling is performed at the MGC, rather than at
the MG itself.
• This enables carriers to deploy less expensive equipment at the
edge of their networks

PSTN v/s NGN
• PSTN
• Proprietary interface,
switch & call control
• Distributed call
control( Main Exgs)
• Dedicated N/W for
voice
• Excellent voice quality
• Vendor dependent
• NGN
• Standard protocol
• Central call control
• Packets
• Good voice quality
• Open source platform

Implementing NGN in BSNLImplementing NGN in BSNL
• STEP- I: IP TAX is the replacement of
existing Level –I/Level-II TAX exchanges
• STEP –II : Implemention at the local exchange
level.

Migration involves
• Replacement of TDM network elements in a phased manner
• Maximum reuse of existing resources
• Use of open and mature standards
• Convergence of access and backbone network
• Continuation of existing network capabilities and services
with same or comparable QoS and security
• Interworking between different types of networks
• Addition of new services

Phase – I: Migration of TAX:
• In first phase of implementation operators can replace their transit
network with soft-switch architecture.
• Operators can make use of the Soft-Switch architecture for the
National Long Distance calls
Present Network Setup

• Local Exchanges have to be connected to Signaling Gateway for signaling
transport.
• Signaling Gateway converts CCS#7 messages to compatible SIGTRAN messages
and sends it towards Media Gateway Controller or Soft-Switch
• MGC instruct concerned originating and terminating media gateways to prepare connection
• When all the condition for the call is met, MGC instruct concerned originating and
terminating media gateways for finally maturing the two communications.
• Both the MGs convert received TDM voice to packets using Real Time Protocol and vice
versa.
• All the communication between MGC and MG is in H.248 protocol.
• The disconnection of the call is informed by the concerned SG to MGC/SS and then MGC/SS
instructs both the MGs to disconnect the RTP link
Phase – I: Migration of TAX:

Soft switch
Local / Tandem
Exchange
Bearer
Bearer
Soft Switching Transit Architecture
Signaling Signaling
TMG
SGWSGW
TMG
Common IP MPLS Transport
STP
Local / Tandem
Exchange
STP
Signaling

Phase II: Migration of Local Exchanges
• In this phase Local Exchanges (LEs) are replaced by the Soft-switch
and Access Gateways (AGW) with same services.
• Soft-switch with local features will be used as a common control
element for class 5 applications.
• Access Gateways (AG) provides various types of access to the
subscribers (e.g. PSTN, ISDN, V5.2, xDSL etc.) and connects them to
IP core network.
• AGs may be configured for various class 5 applications depending on
end user topology, density, service requirements, etc.
• Depending upon the size of the network, a single soft-switch with
class 4 and class 5 applications may be planned

Phase II: Migration of Local Exchanges

Migration from PSTN to NGN
• Necessity
• Network convergence – single network for
voice, data and video
• OPEX and CAPEX savings
• New service opportunities

Migration of Services
• All PSTN services with same equipment, same look and feel should be provided.
• IN and value-added services may be implemented using Application Servers (AS),
which will be accessed by soft-switch via Session Initiation Protocol (SIP).

IMS Architecture
Fully Converged Architecture

NGN BASICS

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NGN BASICS

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