IMS IP Multimedia Subsystem sontungdt7

8/14/2019 IMS IP Multimedia Subsystem sontungdt7

1/38

VKX, Ltd.04/01/09 1/33

IMS IP Multimedia Subsystem

Global Standard, Key Enable for Next

Generation Network

Bui Son Tung IP-Phone Team.

[email protected]


2/38

VKX, Ltd.

Internet Telephony


3/38

VKX, Ltd.

Protocols needed


4/38

VKX, Ltd.

Protocol


5/38VKX, Ltd.

What is SIP?

Session Initiation Protocol - An application layer

signaling protocol that defines initiation,modification and termination of interactive,multimedia communication sessions betweenusers.

IETF RFC 2543 Session Initiation Protocol


6/38VKX, Ltd.

SIP end device


7/38VKX, Ltd.

Simplified SIP Call Setup and Teardown


8/38VKX, Ltd.04/01/09 8/33

What will we cover ?

Description of What is IMS

Why IMS

Services in IMS Network.

IMS Architecture

Key Protocols used in IMS Network.

IMS Operation

Conclusion


9/38VKX, Ltd.04/01/09 9/33

What is IMS

IP Multimedia Subsystem is defined by 3GPP

IMS is a global, access-independent and standard-based IP connectivity

and service control architecture that enables various types of multimedia

services to end-users using common Internet-based protocols (Nokias Engineer)

IMS is defined by wireless standards body 3GPP from Release 5

onwards

IMS builds on IETF protocols

Based upon SIP, SDP and Diameter protocols 3GPP have enhanced these IETF protocols for mobility

IMS - Ericsson

Standardized way to deliver IP-based services that are enabled by one

common core and control for all types of networks

Provides Users with attractive, communication services, over

multi-devices across multi-access technologies.


10/38

VKX, Ltd.04/01/09 10/33

IMS in converged networks


11/38

VKX, Ltd.04/01/09 11/33

IMS in NGN configurations


12/38

VKX, Ltd.04/01/09 12/33

Why do we need IMS

IMS delivers innovative multimedia services over

fixed and mobile networks using open standards.

An enable forconvergence

Fast and efficient service creation and delivery


13/38

VKX, Ltd.04/01/09 13/33

Why do we need IMS

QoS (Quality of Service)

Charging

Service interconnection and

open standards

IMS uses cellular technologies to provide ubiquitous access andInternet technologies to provide appealing services.


14/38

VKX, Ltd.04/01/09 14/33

Service in IMS network.

Presence

Push to talk over cellular

Voice over IP (VoIP)

Messaging

Conferencing

etc


15/38

VKX, Ltd.04/01/09 15/33

IMS Overview (Source from Wiki)


16/38

VKX, Ltd.04/01/09 16/33

IMS Architecture overview


17/38


18/38


19/38

VKX, Ltd.04/01/09 19/33

Interrogating-CSCF

Serves as the initial point of contact from other IMS networks.

Performs a stateless SIP proxy function. Selects a S-CSCF for a user performing SIP registration.

Routes SIP requests received from another network to the S-CSCF. Query HSS for the address of the S-CSCF.

If no S-CSCF is currently assigned (e.g., unregistered subscriber), then assign

SCSCF to handle the SIP request.

Send a SIP request orresponse to: S-CSCF in another operators network.

MGCF for mobile termination call after processing INVITE.

I-CSCF in another operators network (network hiding case).

Provide Topology Hiding Inter-network Gateway (THIG) function.


20/38

VKX, Ltd.04/01/09 20/33

Proxy-CSCF (P-CSCF)

Serves as the initial point of contact for user terminal to network.

Performs a stateful SIP proxy function. Send the SIP REGISTERrequest received from the UE to an

I-CSCF determined using the home domain name, as provided by theUE.

Send all subsequent SIP messages received from the UE to the

S-CSCF, whose name the P-CSCF has received as a result of theregistration procedure.

Insert public useridentity for UE initiated requests.

Perform SIP message compression to reduce the amount of data sent

over the radio interface.

Enforce the bearer resources as negotiated in the SDP when Service.Based Policy is used.


21/38

VKX, Ltd.04/01/09 21/33

S-CSCF Routing and Basic IMS Session


22/38


23/38

VKX, Ltd.

Home Subscriber Server (AAA+DB)

The HSS supports IMS

level Authentication, and

Authorization.

Holds location, security,

user profile. Keeps track of currently

assigned S-CSCF.

Supports CSCF and AS

access.

04/01/09 23/33

A li i S (AS)


24/38

VKX, Ltd.04/01/09 24/33

Application Server (AS)

The Application Server provides service control for

IMS.

May be directly connected to S-CSCF or via OSA

Gateway for 3rd party security.

Interacts with the HSS to obtain subscriber profile

information.

May support applications such as presence,

conference control, online charging, etc.

MGCF d MGW


25/38

VKX, Ltd.04/01/09 25/33

MGCF and MGW

IMS A hi R i


26/38

VKX, Ltd.04/01/09 26/33

IMS Architecture Review

K P t l d i IMS


27/38

VKX, Ltd.04/01/09 27/33

Key Protocols used in IMS Session Initiation Protocol (SIP)

SIP is the main signalling protocol used in IMS networks.

The function of SIP is to establish, modify and terminate multimedia sessions withmedias such as voice, video and chat over IP networks, where the media delivery part is handledseparately.

Diameter the Authentication, Authorization, and Accounting protocol A development of the current RADIUS protocol, Diameter is used by the S-CSCF, I-CSCF and the SIP application servers in the Service

Layer, and in theirexchanges with the HSS containing the user and subscriber

information.

Compared with RADIUS, Diameter has improved transport it uses Transmission

Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP), and not UDP, as

transport improved proxy, enhanced session control and higher security. H.248 media control protocols

H.248 is a control protocol used between media control functions and media resources. IPv6

Internet Protocol version 6 (IPv6) is a network-layer IP standard used by devices to

exchange data across a packet-switched network. IPv4 : 32bits => 4,2 billion address IPv6: 128bits => 5 * 10^28 address

IMS O ti O i


28/38

VKX, Ltd.04/01/09 28/33

IMS Operation Overview

SIP Registration

IMS Origination to IMS Subscriber

IMS Origination to PSTN/PLMN

PSTN UE to IMS UE

SIP R i t ti / R i t ti


29/38

VKX, Ltd.04/01/09 29/33

SIP Registration/ Re-registration


30/38

VKX, Ltd.04/01/09 30/33



31/38

VKX, Ltd.04/01/09 31/33



32/38

VKX, Ltd.04/01/09 32/33

Example SIP Call


33/38

VKX, Ltd.

33

Example SIP Call

IMS Origination to PSTN/PLMN (option 1)


34/38

VKX, Ltd.04/01/09 34/33




35/38

VKX, Ltd.04/01/09 35/33


PSTN to IMS UE (initial contact is MGCF)


36/38

VKX, Ltd.04/01/09 36/33

PSTN to IMS UE (initial contact is MGCF)

Key points to take home


37/38

VKX, Ltd.04/01/09 37/33

Key points to take home

IMS is stable and clearly specified by 3GPP in Rel-6

IMS is the platform of choice for Mobile to Fixed convergenceStandardisation involves close coordination between different

bodies such as IETF, 3GPP, TISPAN, OMA, ITU-T, etc.

Robust and open global standards are essential to the long term

success of IMS and NGNDoing Nothing is NOT a sensible option

Better to have planned convergence than unplanned collision

If you want to influence the standardization process, the time is

to do it is NOW


38/38

VKX, Ltd.04/01/09 38/33

and finally.

Thank you for your attention

Now Time for your Questions

Documents

IMS IP Multimedia Subsystem sontungdt7