NGN & IMS

The Core Network

NGN & IMS

Samuel Dratwa
Samuel.dratwa@gmail.com

Copyright © 2011 LOGTEL

Agenda

 Why do we need NGN ?
 What is NGN ?
 What is IMS
 What is the different between IMS & NGN
 The Transport layer
 IPv6
 The Control layer (core)
 IMS
 Policies / PCRF
 The Service layer
 M2M


Network topology today

BT – 21cn


Converged network

BT – 21cn


The Dream Carrier Network

HD TV Business, Voice/Video
TVoD, VoD ERP Telephony Voice
Services gateway
Business
Video Video Services
Source Source

Business
Access Carrier
Network
Mobile
Access Residential
Internet
Triple-Play
Access
Networks

The Dream Carrier Network
- All traffic converges into one network
- Connectivity to Services, Applications, Other Sites, The Internet
- With the necessary Quality of Service and Security

A Next Generation Network
We must Rebuild the Networks
 Common service delivery
infrastructure
 Standardised, open interfaces
 Seamless service delivery
 Single packet infrastructure for
media and control
 Rich, multimedia services
 Simpler network
 Separation of control, apps and
subscription
 Faster delivery of services
 Interfaces with the access
network
 Access independence
 Advantage for “pipe” owners

Many multimedia applications  single end-user experience.
Deliver to any access type.

So What is NGN ?


The NGN Concept – Six Key Criteria

packet-oriented
network

integration of support broad
existing variety of
infrastructure services

NGN
application openness and
focused - flexibility
access regarding new
independent services
separation into
different layers
using open
interfaces


NGN Layered Architecture

NGN Planes Planes and functions

Application Plane Application Plane enables the provisioning of
services and provides the control and logic for the
Value Added Service Creation
execution of services

Control Plane Control Plane controls the elements of the network,
Basic control service establishes and clears media connections

Management Plane
Transport Plane is responsible for the transport of
Transport
Plane media and signaling messages
Packet Based Transport
Management Plane covers network management
ensuring service fulfillment, service assurance
and billing
Access Networks
Access Networks connect customer networks or
terminals with the components of the NGN
network and aggregate the dedicated traffic type


From Networks to Services

Legacy Model New Model
Services Services

Data (FR, etc..)
Cellular Mobile
Mobile

CATV
PSTN

Access, Transport & Switching Networks Connectivity Networks

Hide the different networks from the user and offer services over IP


So what does this mean
 NGN - A Next Generation Network is an IP packet based network
able to provide Telecommunication Services.
 The NGN can make use of multiple broadband, QoS enabled
transport technologies and the service-related functions are
independent from underlying transport-related technologies.
 Currently everything seems to be NGN
 Ethernet
 PON
 IP/MPLS
 3G, 4G
 Wi-Fi, WiMAX
 Virtualization
 VOIP, SIP
 IP TV
 NGN is targeted at the ability to deliver the services not the
network
 In many senses it is a marketing driven term


Making Standards

12

Migration to NGN
Internet
Multi-
Mobile PSTN Internet Video Mobile VoIP Video
Media
Services
Management

IMS
Service
Applications

Call/Session
Control

Switching &
Transport

User Device


IMS – IP Multimedia System
 IP Multimedia Subsystem (IMS) is a Service Delivery Architecture
 Standardized architecture to provide Internet Protocol (IP)-based
mobile and fixed multimedia services
 Developed in the Framework of 3GPP-UMTS Mobile Architecture

 FMC – Fixed Mobile Convergence

 IP Based Convergence
 On any Device
 On any Network
 Common Applications

 Service Ubiquity - anywhere, anytime, on any device
 One phone number
 Unified Communications/Messaging
 Unified Presence
 One System to manage device and media types
 Centralized Database of user preferences/location/features

 Fast Introduction of New Multimedia Services

 Based on the SIP Protocol

What does IMS provide?

 Services and Control
 Adds call session control to the packet network
 enables peer-to-peer real-time services - such as voice, video
- over a packet-switched domain
 Mixed Multimedia
 Ability to pick and mix various multimedia flows in single or
multiple sessions
 Can handle real-time voice, video, data
 Connectivity Independence
 Provides access to IP based services independent of the
connectivity network: mobile (3GPP’s UMTS, 3GPP2’s
CDMA2000) and fixed networks (TISPAN’s NGN)

Copyright © 2011 LOGTEL 15

IMS Architecture

Services plane Application Application Application
(Application Layer) Server Server Server

Session Control Plane Session Control Centralized
(Session and DB Layer) Databases
DB

Media Control Plane
(Media Control Media Control
& Gateway Layer) & Gateways

Network Plane
(Access and Transport) 2G/3
Wireline G
Wireless PSTN
Broadband Mobil
Res./ Broadband
e
Enterprise


IMS Status – early 2010
 8% of 101 Operators Interviewed have deployed IMS
 None of these have completed conversion and estimate a 5-7 year
process
 A further 12% are in extended field trails
 Mainly the IMS core network
 Not yet service migration
 IMS not yet in rapid adoption
 Linear adoption to 32% of operators by 2014
 Regional Adoption
 Main growth 2010 - 2011 in N America
 EMEA and APAC in later years
 Top 3 inhibitors
 Lack of Business Case
 Lack of standards compliance
 BSS and OSS Integration Issues

Source: Alan Quayle Report – 2010

IMS Reported Deployments
 Sprint – IMS Core, FMC Services
 Telefonica – IMS Core
 Cox Cable – some trials
 Telinor
 Telecom Italia Mobile – Video Sharing Service
 TeliaSonera
 Verizon – IMS and LTE
 China Mobile
 Far East one Telecom. In Taiwan was one of the first to offer
services the use IMS. In the 2nd half of 2007 it launched a voice
service using VOIP over WiFi over HSPA via a fixed wireless
terminal.
 BT is implementing IMS as part of 21CN NGN.
 China Telecom is conducting a trial of IMS
 France Telecom/Orange is looking at IMS for fixed/mobile
convergence business services.
 Rogers Communication in Canada has conducted a trial of
converged IMS and quadruple-play services.


NGN Transport Layer

NGN Layers Layers and functions

Application Plane Application Layer enables the provisioning of
Value Added Service Creation services and provides the control and logic
for the execution of services
Control Plane
Control Layer controls the elements of the
Basic control service
network, establishes and clears media
connections
Transport Plane

Packet Based Transport Transport Layer is responsible for the
transport of media and signaling messages

Access Networks Layer connect customer
Access Networks
networks or terminals with the components
of the NGN network

Devices


Why IP?

Router Router
Router
MAN ATM

Broadband
Router Host Sites

LAN
Router
Access Router Router
WAN
Sonet

Mobile

 Users are connected to specific network technologies (LAN, WAN)
 IP is a technology that enables network interconnection and any-to-any
connectivity
 IP runs on top of all the well known specific network technologies
 The applications run on top of IP

 IP is not the Internet

The Carrier Network
Business

Corporate

Residential Content

WiMAX Metro Core
Mobile
Access Si
Aggregation Network
Network
Business IP / MPLS
Corporate Fiber

Residential Internet
Metropolitan Network: Core:
DSL/Cable
Access Carrier Ethernet
IP/MPLS

Access:
STB  xDSL
Transport Network
 Cable
 WiMax
 Fibre
 Mobile

IP Packets

Telephony Signaling and Speech

H.323/SIP Signaling

IP network

RTP Media Stream

Separation of signaling and media is achieved
by using separate Communications Ports


SIP – Session Initiation Protocol
 SIP enables telephony and multimedia conferencing over an IP Network
 Based on SMTP, HTTP
 Features
 User Location – DNS style Address resolution, name mapping, call redirection
 User Capabilities – Determination of the endpoint media capabilities
 User Availability - Dynamic discovery of endpoint availability
 Call Handling - Session origination, termination and management between
hosts and endpoints
 SIP Addresses
 user@host (URL or URI- Universal Resource Identifier)
 SIP defines a simple IP style protocol environment
 IETF RFC industry standard
 Call control only, does not define media transport protocol
 Designed to integrate with Web, eMail, streaming ….

 Mobility enabler:
 Personal mobility - one person, multiple terminals
 Terminal mobility - one terminal, multiple IP addresses
 Session mobility - one user, multiple terminals in sequence or in parallel
 Service mobility - services move with user


So why isn’t it here yet ?

 No clear move to IPv6
 Lack of smooth migration plans
 Investments in IPv4
 Software availability - Available from Microsoft Windows XP sp2
 Developments in IP v4
 Use of NAT
 CIDR
 Planning of Hierarchies and use of Autonomous Areas
 IPsec implemented in IPv4
 Other Points
 Router Upgrades to handle IPv6 – OSPFv3


IMS / NGN Control Layer

NGN Layers Layers and functions

Application Plane Application Layer enables the provisioning of
Value Added Service Creation services and provides the control and logic
for the execution of services
Control Plane
Control Layer controls the elements of the
Basic control service
network, establishes and clears media
connections
Transport Plane

Packet Based Transport Transport Layer is responsible for the
transport of media and signaling messages

Access Networks Layer connect customer
Access Networks
networks or terminals with the components
of the NGN network

Devices


IMS Network - Elements and Protocols

Home Subscriber Server Application Servers
• Centralized DB • Push-to-talk
Media Resource Function Controller
• Pooling of Media servers (e.g. conference)
• HLR successor • Instant messaging
• User profile • Telephony AS
• Filter criteria (sent to S-CSCF) • 3rd party or IMS Vendor
• Which applications
• Which conditions Home Network
UA/UE
SIP
DNS AS
AS P-CSCF
ENUM
HSS AS Media Gateway
Diameter Control Function
SIP • Interfaces to PSTN/PLMN by
• Converting SIP <-> ISUP
SIP
UA/UE P-CSCF I-CSCF
SIP
S-CSCF MRFC • Interworking RTP to circuit
SIP • H.248 control of MGW
MS MS
SIP
SIP
SIP
SIP
BGCF MGCF
ISUP
Call Session SIP
H.248 SS7
Control Function
• SIP registration RTP TDM PSTN
• SIP session setup MGW

Proxy CSCF Serving CSCF
Visited • Registrar
• 1st contact point for UA
Network • Session control
• QoS
• Application Interface
• Routes to S-CSCF
Interrogating CSCF
• Entry point for incoming calls Breakout Gateway Control Function
• Determines S-CSCF for Subscribers • Selects network (MGCF or other BGCF)
• Hides network topology in which PSTN/ PLMN breakout is to occur


An Example of an IMS Call

Network X Network Y
AS
AS
S-CSCF
S-CSCF

HSS
HSS I-CSCF

P-CSCF

P-CSCF
GGSN UMTS
Packet
Core
DSL/Cable Modem

SGSN

DSLAM/CMTS

RNC

User B
User A


IMS Emergency Services Network
Call Delivered to
IP PSAP with
Location is Used to Location
Determine PSAP

PSAP
SIP
Access DNS Selection
HSS AS
AS P-CSCF SIP
ENUM AS
RTP IP PSAP
SIP Diameter
RTP SIP
SIP

Backbone P/S- SIP SIP SIP MRFC
Packet I-CSCF S-CSCF
SIP CSCF
Customer Network
MS MS
SIP
Home SIP
Network BGCF
SIP
MGCF
ISUP
IMS Emergency H.248 SS7

RTP
Services Network TDM Selective Router
MGW

Call Enters IMS ESNet CAMA
With Location CAMA E-MF
E-MF

OR
Call Delivered to Legacy Network
Without Location Legacy PSAP
(Query for Location Needed)
*PSAP – Public Safety Answering Point


Vulnerabilities

IMS & SIP enable a rich feature set of HSS Apps Chrg

Converged Services ….. but also open SIP Server
P/S/I
Call Server

up the network to IP based
MGCF
CSC MRFC
F BGCF
SLF/PDF/IBCF/I

vulnerabilities. WF SGF

IMS core
ABGF MGW
IBGF MRFP
T-MGF
IP-IP GW
Media Gateway

IMS & SIP vulnerabilities include:
OS level vulnerabilities
Well known in the data world
IP Layer 3 vulnerabilities
IMS Framework related vulnerabilities New, unique
&
SIP/RTP/H.248/etc. protocol vulnerabilities
real time
VoIP/Video/PoC/etc. Application vulnerabilities sensitive
Application
VoIP SPAM level
vulnerabilities

Access Security

Authentication

ISIM
AKA
HSS
Security Association

UA
IPSec
P-CSCF

ISIM - IP multimedia Services Identity Module
UA – User Agent
AKA - Authentication and Key Agreement Protocol


Network Security
 Network Security Interfaces have been defined
 Within the same network domain
 Within the same domain it is up to the Operator to define security policy
 Between Network domains
 Between domains a security architecture has been defined
 At the border of each domain a Security Gateway (SEG) is used. The Security Gateway concept is
based on the SBC – Session Border Controller Concept

Network Operator
Network Operator A
B

CSCF
SEG SEG CSCF

CSCF
CSCF

SEG – Security Gateway


Policy & QoS Management

Real-time Broadband
Fulfillment

Email,
FTP,
Gopher

E-Text E-Commerce Experience-based

Static Network Policies Dynamic Network Policies Real-time User Policies

Fixed/Mobile IP
IP TDM IP Access IP Broadband IP Multimedia

With more interactive and dynamic services, policy and control becomes
increasingly important to ensure consistent, quality services


Real-time allocation of network resources

1. User requests mobile video
service, which is directed to
the policy engine
2. Policy engine intelligently
IMS Service Complex
interacts with network to Service Request
reserve bandwidth
Policies
3. Video delivered to mobile
user with assured quality Video Stream

Access IP Network
GGSN/
PDSN RCEP

Policy and QoS requests handled by a Policy Decision Function

LTE roaming overview

Roaming border
Visited network Home network
MME PCRF PCRF HSS
1 Attach

2 Authenticate 2 Authenticate

3 Update Location

Subscriber Data 4

Policy exchange 5


NGN & IMS

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