Bai Giang Umts_giangdl

8/12/2019 Bai Giang Umts_giangdl

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User IdentityUser Identity

Private identity Issued by home provider

Used for AAA

Saved on ISIM (not modifiable)

Public identity Normal SIP address (URI or TEL)

Identifies the user publicly

User has one or more identities

PrivateUser Identity 1

PublicUser Identity 1



ImplicitlyRegistered ID

Set 1



Set 2

ServiceProfile 1ServiceProfile 2

ServiceProfile 3

IMSSubscription

V. Mancuso, I. Tinnirello

Used for routing Can be grouped into implicit registration sets

If one of the set is registered then the others are as well

At least one is stored on ISIM In case no ISIM is provided

Use a temporary identity derived from USIM during initial registration (derived from

IMSI)

PIDs are then provided by the S-CSCF in its reply to the registration


Set 3PrivateUser Identity 2 PublicUser Identity 5

PublicUser Identity 6 ServiceProfile 4


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UICCUICC

Universal Integrated Circuit Card

Used to store data, including authenticationinformation

Contains one or more applications SMS

Phonebook

SIM


GSM Subscriber Identity Module USIM

UMTS SIM

ISIM

IMS SIM

Applications are independent SIM, USIM and ISIM can coexist on the same UICC

but SIM cannot be used for IMS access (for security reasons)


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IP Multimedia SubsystemIP Multimedia Subsystem

A standard

An enabler

of new

applications

Next-gen

network

architecture

SIPIMSIMSIMSIMSConverged ServicesConverged ServicesConverged ServicesConverged Services

Rich CommunicationsRich CommunicationsRich CommunicationsRich Communications


ServiceServiceServiceService----layerlayerlayerlayer

ControlControlControlControl----layerlayerlayerlayer

TransportTransportTransportTransport----layerlayerlayerlayer

IMS is access agnostic, cost reducing, and serviceIMS is access agnostic, cost reducing, and serviceIMS is access agnostic, cost reducing, and serviceIMS is access agnostic, cost reducing, and service

enhancingenhancingenhancingenhancing

IMS gives the customer & carrier choiceIMS gives the customer & carrier choiceIMS gives the customer & carrier choiceIMS gives the customer & carrier choice

SIP

SIP SIPSIP

At HomeAt HomeAt HomeAt Home In the OfficeIn the OfficeIn the OfficeIn the OfficeOn the MoveOn the MoveOn the MoveOn the Move

IP NetworkIP NetworkIP NetworkIP Network

SIP

usususus ---- ---- aaaaPushPushPushPush----2222----ViewViewViewView

PushPushPushPush----2222----XXXX

Presence, LocationPresence, LocationPresence, LocationPresence, Location----based Servicesbased Servicesbased Servicesbased Services

Interactive Services,Interactive Services,Interactive Services,Interactive Services,Interactive GamingInteractive GamingInteractive GamingInteractive Gaming

Games,Games,Games,Games,MusicMusicMusicMusic

DownloadsDownloadsDownloadsDownloads

PicturePicturePicturePictureMessaging,Messaging,Messaging,Messaging,

MM MessagingMM MessagingMM MessagingMM Messaging

VoiceVoiceVoiceVoice

Video ClipsVideo ClipsVideo ClipsVideo ClipsSports, NewsSports, NewsSports, NewsSports, News

EEEE----mailmailmailmailIMIMIMIM

StreamingStreamingStreamingStreamingAudio, VideoAudio, VideoAudio, VideoAudio, Video


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IMSIMS


Goals & Tools


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IMS goalsIMS goals

Combine latest trends in tech

Run fast, no time for standardization of services

Mobile/Nomadic internet

Create a platform for multimedia


services and their development

Exploit/allow mobile packet-

switching networks

Not a mere circuit-switching replacement


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IMS requirementsIMS requirements

Support for establishing IP MultimediaSessions Audio, video, messaging

Support for mechanisms to negotiate QoS distinguish users


Support for interworking with Internet with packet-switching networks

Support for roaming Home and visited network Inter-operators roaming


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IMS requirementsIMS requirements (contd)(contd)

Support for user activity control policies imposed by the operator (general policies and per-user policies) accomplish to service agreements

Support for fast service creation


Standardize service capabilities instead

Support for multiple access Not only GPRS, UMTS IP is independent on lower protocol layers


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Protocols in IMSProtocols in IMS

3GPP reuses protocol developed by otherstandards development organizations ETSI (European Telecommunications Standard Institute) IETF (Internet Engineering Task Force) ITU-T (International Telecommunications Union - Telecommunications)

3GPP interacts with standards


development of existing and newprotocols

Protocols RTP for media transport

Session control protocols AAA protocols Other


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Session Control ProtocolSession Control Protocol

SIP (Session Initiation Protocol, byIETF- RFC2821)

Protocol to establish and manage multimedia sessionover IPSIP borrows some design principles from SMTP and


Does not differentiate the user-to-network interface fromthe network-to-network interface (unlike BICC andH.323)

It follows the client-server modelText-based protocolEasy to debug, extend and reuse for service building


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AAA protocol: DIAMETERAAA protocol: DIAMETERone protocol for many interfacesone protocol for many interfaces

Authorization What service can be used?

Authentication

Are you really who you say youare?

Accounting $

Diameter

Client Application

Diameter

Server Application

Session Management Session Management


Routing Management

Connection

Management

Connection

Management

Base Protocol Base Protocol

Routing Management

DIAMETER

by IETF RFC3588

Evolution of RADIUS

Base protocol Diameter applications Diameter applications used to customize/extend the base protocol for different interfaces, environments, and

applications

E.g.: interact with SIP session setup (Authorization and Authentication)

E.g.: interact with the billing subsystem to control accounting

E.g.: interact with routing entities


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IMS ArchitectureIMS Architecture



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New services for mobileNew services for mobile

and fixed networksand fixed networks Open, standardised, operator friendly, NGN

multimedia architecture for mobile and fixed services

Based on SIP, DIAMETER and COPS controls Supports legal interception, localisation, PSTN interworking, etc.


Access Independent

MGW

3G mobile

PSTNPSTN

IP transport

IMS PlatformWLANWiMAX

DSLFibre

Ethernet

ApplicationsInternetInternet


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Functions and nodesFunctions and nodes

IMS standardizes functions

IMS does NOT standardize nodes

The IMS Architecture is a collection offunctions linked by standardizedinterfaces


A function can be implemented through one or more nodesMultiple functions can share a node

Commonly a function per node


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A standard architecture forA standard architecture for

service deliveryservice delivery

ASApplication

Layer

SessionSIP

SIP

DIAMETER

AS

SIPMR


MGCFLayer

ConnectivityLayer PSTN/PLMNPSTN/PLMNPSTN/PLMNPSTN/PLMN

IP Network

H.248SIP

CPE

MGW

GGS

N


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Access to IMSAccess to IMS

The user can connect to an IMS network invariety of ways, all of which use thestandard Internet Protocol (IP) for packetswitchinge.g., IMS terminals can register directly

on an IMS network


. ., ,

even when they are roaming in another network or country (the visitednetwork)

The only requirement is that they can use IPv6 (also IPv4 in early IMS)and run SIP user agents


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Other access examplesOther access examples

Fixed access

- e.g., Digital Subscriber Line (DSL), cable modems, Ethernet

Mobile access e.g., W-CDMA, CDMA2000, GSM, GPRS

Wireless access


e.g., WLAN, WiMAXOther phone systems like plain old

telephone service (POTS -- the oldanalogue telephones) or PSTN, H.323

and non IMS-compatible VoIP systems,are supported through gateways


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IMS functional elementsIMS functional elements



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Infrastructure of SIP ProxiesInfrastructure of SIP Proxies

(media do not traverse the IMS..)(media do not traverse the IMS..)



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IMS Functional ElementsIMS Functional Elements

Session Management (SIP)

Routing

Databases

Network Interoperability Elements


Services and Support ComponentsCharging Components


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Nodes/Functions in the IMSNodes/Functions in the IMS

User databases HSS (Home Subscriber Server) SLF (Subscriber Location Function)

SIP servers CSCF (Call/Session Control Function)

AS (Application Server)


MRFC (MRF Controller) MRFP (MRF Processor)

BGCF (Breakout Gateway Control Function)PSTN/CS gateways, decomposed into: SGW (Signaling Gateway) MGCF (Media Gateway Controller Function) MGW (Media Gateway)

Charging collection functions


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Databases (HSS,SLF)Databases (HSS,SLF)

HSS is an evolution of the HLR (HomeLocation Register) of GSM

Contains the user-related subscription data (e.g., location,authorization and authentication information)

More than one HSS is possible


If #HSS > 1 SLF requiredSLF maps users address to HSSs

HSS and SLF use DIAMETER with an IMS-

specific diameter application


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Home Subscriber Server (HSS)Home Subscriber Server (HSS)

Presence, Location and Profile

End-User Identity

HSSHSS

Diameter


Private and Public End-User InformationRegistration Information

Service Initiation Information

Subscriber Service Profile (SSP)Downloaded to CSCF at Registration


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More on HSSMore on HSS

HSS is a masteruser database thatsupports all the IMS network functions

that actuallyhandle communicationscontains the subscription-related information (user profiles)

performs authentication and authorization of the user


can provide information about the user's physical locationis similar to the GSM Home Location Register (HLR) and

Authentication Centre (AUC) together


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CSCFCSCF

SIP servers or proxies, collectively called CallSession Control Function (CSCF), are used to

process SIP signaling packets/messages inthe IMS

P-CSCF (Proxy)


I-CSCF (Interrogating)S-CSCF (Server)


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Call/SessionCall/Session ControlControl FuncFunc. (. (CSCF)CSCF)

CSCF Processes SIP Signaling P-CSCF

First Point of User Contact (located in the visited domain)

II--CSCFCSCF

SS--CSCFCSCF

PP--CSCFCSCF

SIP

SIP

SIPSIP

SIP

Diameter


May Include Policy Functions S-CSCF

Central Node of Control Plane Acts as Registrarfor User (located in the home domain) Invokes Application Servers Performs Primary Routing Function

I-CSCF Located at Edge of Administrative Domain (contact point for inter-domain messages) Is the Ingress Network Point Defined in DNS Shields Network Topology from External Networks


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IMS Signaling PathIMS Signaling Path(1 domain, no roaming)(1 domain, no roaming)



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IMS Signaling PathIMS Signaling Path(4 domain roaming, media goes directly)(4 domain roaming, media goes directly)

IrishUser

SwedenUser


Irish UserIn roaming

Sweden UserIn roaming


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CSCFCSCF

P-CSCF (Proxy)

Outbound/Inbound proxy server

First server contacted by the user

Fixed while registered


, ,

Authenticates the user and extend the authentication toother nodes within IMS

Compress/decompress SIP messages

Generates charging info


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PP--CSFC detailsCSFC details

SIP proxy that is the first point of contact for the IMSterminal

It can be located either in the visited network (in full IMSnetworks) or in the home network (when the visited

network isn't IMS compliant yet) The terminal discovers its P-CSCF with either DHCP

or it is assigned in the PDP Context (GPRS) It is assigned to an IMS terminal during registration, and


oes no c ange or e ura on o e reg s ra on

It sits on the path of all signaling messages, and caninspect every message

It authenticates the user and establishes an IPsec securityassociation with the IMS terminal

Other nodes trust the P-CSCF, and do not have to authenticate the user again

It can also compress and decompress SIP messages it may include a Policy Decision Function (PDF), which

authorizes media plane resources it also generates charging records


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PDF forPDF for QoSQoS in IMSin IMS(intermediary between the application(intermediary between the application--level QOS andlevel QOS and

the 3G networkthe 3G network--levellevel QoSQoS))



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CSCFCSCF

I-CSCF (Interrogating)

SIP proxy at the edge of a domain

Advertised by DNS

Interface to HSS and SLF for routing purposes


Optional: encryption of sensitive information aboutthe domain (THIG: topology hiding inter-networkgateway)


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II--CSCF detailsCSCF details

It is another SIP function located at the edge of anadministrative domain

Its IP address is published in the DNS of the domain remote servers can find it, and use it as a forwarding point (e.g. registering) for

SIP packets to this domain The I-CSCF queries the HSS using DIAMETER to

retrieve the user location then it routes the SIP re uest to its assi ned S-CSCF


Up to Release 6 it can also be used to hide theinternal network from the outside world (encryptingpart of the SIP message) in which case it's called a THIG(Topology Hiding Inter-network Gateway) From Release 7 onwards this "entry point" function is removed from the I-

CSCF and is now part of the IBCF (Interconnection Border Control Function)which is also a firewall and a nat.


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CSCFCSCF

S-CSCF (Server)

SIP server with session control functions

SIP registrar (maintains a mapping between userlocation and public user identity)


SIP routingPEP

Always located in the home network

Interfaced with the HSS (e.g., to download theusers profile)

d ild il


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SS--CSCF detailsCSCF details

It is the central node of the signaling plane SIP server + session control

It is always located in the home network It uses DIAMETER to the HSS to download and

upload user profiles

All necessary information is loaded from the HSS. It handles SIP registrations

bind the user location and the SIP address

It sits on the ath of all si nalin messa es and can


inspect every message

It decides to which application server(s) the SIPmessage will be forwarded, in order to provide theirservices

It provides routing services, typically usingElectronic Numbering (ENUM) lookups

There can be multiple S-CSCFs in the network forload distribution and high availability reasons

It's the HSS that assigns the S-CSCF to a user, whenit's queried by the I-CSCF.


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Application Server (AS)Application Server (AS)

Contains Call Related Application Logic

ASASASAS

ASAS

SIP

Diameter


Queried by S-CSCF in Real Time to Execute Logic Filters can be applied at S-CSCF in order to inspect the SIP messages and

decide whether involve or not the AS

Generally Specialized for Each Service

May Provide Gateway to Legacy Applications (e.g.AIN)

Can Behave as a SIP Proxy or Terminal (and in thiscase receive the media!)


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ASAS

Three different AS types SIP AS

native IMS application server

OSA-SCS (Open Service Access Service Capability Server)Interface to Open Service Application (AS) framework application

server (developed by 3GPP for UMTS)

IM-SSF (IP Multimedia Service Switching Function)


Reuse/interface with CAMEL (GSM)

Gateway for GSM Service Control Function

An AS can be located in the homenetwork or in an external third-party

network If located in the home network, it can query the HSS with the DIAMETER

Sh interface (for a SIP-AS) or the Mobile Application Part (MAP) interface(for IM-SSF).


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T i lT i l


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ASAS asas a SIP Terminala SIP Terminal(e.g. web server: receive media data!)(e.g. web server: receive media data!)


E l f Fil R lE l f Fil R l


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Example of Filter RuleExample of Filter Rule(at S(at S--CSCF)CSCF)

User A wants to divert all calls from bossto an answering machine (i.e. the AS)

(method=INVITE) AND(P-Asserted-Identity = [email protected]) AND

(Session Case = Terminating) ->message is addressed to



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Multimedia Resource Function (MRF)Multimedia Resource Function (MRF)

SIP

MSMS MSMS

MRFCMRFC


Offers Services Such as Conferencing

MRFC SIP User Interface toward S-CSCF

MRFP Controls the Media Server (MS)


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MRFMRF

The MRF (Media Resource Function) provides asource of media in the home network

It provides media related functions such as media

manipulation (e.g. voice stream mixing, mediatrans-coding) and playing of tones andannouncements.

Each MRF is further divided into


Media Resource Function Processor (MRFP) media plane

The MRFC acts as a SIP User Agent to the S-CSCF,and controls the MRFP with a H.248 interface

The MRFP is a media plane node that implements

all media-related functions

M lti t C llM lti t C ll


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Multiparty CallsMultiparty Calls(MRF as a special AS)(MRF as a special AS)


REFER:

Ask otherto join


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Multiparty CallMultiparty Call



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Multiparty CallMultiparty Call



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BGCFBGCF

The Breakout Gateway Control Function is aSIP server that includes routingfunctionality based on telephone numbers

used when calling from the IMS to a phone in a circuit switchednetwork


e.g., o u c w c e e ep one e wor or o

Public Land Mobile Network (PLMN)

BGCF routes to the appropriate (remote)circuit switching domain

BGCF selects the (local) PSTN/CS gateway

TT


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PSTN GatewayPSTN Gateway

MGCFMGCF

H.248

ISUP

BGCFBGCF SIP

SIP

SGWSGW

SIP


BGCF Routes to Gateway Based Upon TelephoneNumber

MGCF Controlling Function for SGW and MGW

SGW Provides Signaling Conversion Between SIPand ISUP

MGW Provides Conversion between RTP and TDM

MGWMGWTDM

Home NetworkHome Network -- Functional ElementsFunctional Elements


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Home NetworkHome Network Functional ElementsFunctional Elements

HSSHSSDNSDNS

ENUMENUM

Home Network

ASASASASASAS

Home Subscriber Server

Centralized DB HLR successor User profile Filter criteria (sent to S-CSCF)

Which applications Which conditions

Application Servers Push-to-talk Instant messaging Telephony AS 3rd party or IMS VendorDomain Name Server

SIPDiameter

Media GatewayControl Function Interfaces to PSTN/PLMN by

Converting SIP ISUP

Media Resource Function Controller Pooling of Media servers (e.g. conference)

PP--CSCFCSCFSIP

UA/UE


VisitedVisitedNetworkNetwork

II--CSCFCSCF SS--CSCFCSCFPP--CSCFCSCF

MGCFMGCF

MGWMGWPSTNPSTN

H.248

ISUPBGCFBGCF

SIP

SS7SS7

SIP

SIPSIP

SIP

RTP TDM

Call SessionControl Function SIP registration SIP session setup

MSMS MSMS

Interworking RTP to circuit H.248 control of MGW

Breakout Gateway Control Function Selects network (MGCF or other BGCF)

in which PSTN/ PLMN breakout is to occur

Proxy CSCF 1st contact point for UA QoS Routes to S-CSCF

Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers

Hides network topology

Serving CSCF Registrar Session control Application Interface

SIP

UA/UE


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NetworkNetwork--toto--Network ConnectivityNetwork Connectivity

HSSHSSDNSDNS

ENUMENUM

SIP

ASASASASASASAccessAccess

SIP

SIPDiameter

RTP

RTPPP--CSCFCSCF SIP

SIP

UA/UE


II--CSCFCSCF SS--CSCFCSCF

VisitedNetwork

HomeNetwork

P/SP/S--CSCFCSCFPacketPacketNetworkNetwork

MGCFMGCF

MGWMGWPSTNPSTN

H.248

ISUPBGCFBGCF

SIP

SS7SS7

SIP

SIPSIP

RTP TDM

MSMS MSMS

Proxy/Serving CSCFManages call originationSelects destination network Routes to I-CSCF

Interrogating CSCF Entry point for incoming calls Determines S-CSCF for Subscribers

Hides network topology

H d Vi it d N t kH d Vi it d N t k


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Home and Visited NetworksHome and Visited Networks

Inherited from 2G, 3G

Most of IMS nodes and functions are locatedin the Home network

P-SCFC can be either in the home or visitednetwork

-


simplifies the operators managementallows roaming to non-IMS GPRS CANs (Connectivity Access networks)

Drawback: trombone effect when GGSN is in the home network (GGSN isin the media plane)

In a long term perspective the P-CSCF will be located in the visited

network

Media servers can be out of both


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IMS architectureIMS architecture


Examples

John is calling BettyJohn is calling Betty


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John is calling BettyJohn is calling BettyIIntroducingntroducing the HSS and the Sthe HSS and the S--CSCFCSCF

The HSS is the table user/address

The S-CSCF is a SIP proxy which workson messages to provide users

(consumers, enterprises) with callingservices including registration being amediation SIP2DIAMETER

HSS

When the phones

get connected they


SIP S-CSCF

register their

name/IP to the HSS

Changes the SIP message replacing Betty by its IP

address found in the HSS

SIP

John is calling a taxi to meet BettyJohn is calling a taxi to meet Betty


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John is calling a taxi to meet BettyJohn is calling a taxi to meet BettyIntroducingIntroducing the Application Server (AS)the Application Server (AS)

In addition to the basic name/address translation,the S-CSCF routes SIP messages to: The network of Betty, if different

The applications such as: Push-To-Talk, Instant Messaging, Advance Call Control,Voice/video mailbox, nearest Taxi running on AS, a SIP proxy application server


S-CSCF

AS

nearest Taxi application (location, fleet)

Changes the SIP message replacing taxi by

the IP address of the nearest available taxi

Johns and Bettys phones doJohns and Bettys phones do not supportnot support a commona common


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y py p pppp

voice encodingvoice encoding

Introducing the MRFC and MRFPIntroducing the MRFC and MRFP

Intercepting the SIP invite message, the S-CSCF/AS

detects a non compatibility between the codecs of thephones : it forwards it to the MRFC (a SIP proxy).

The MRFC adjusts the SIP messages in order to orient theRTP flow to the MRFP a RTP rox for trans-codin


MRFC

MRFP

MGCP, H248 Megaco

RTP (codec: AMR)

SIPS-CSCF

RTP (codec: G729)

During its travel John is calling BettyDuring its travel John is calling Betty

ThTh t h d t ti f it i fft h d t ti f it i ff


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TheThe operator has made a segmentation of its services offeroperator has made a segmentation of its services offerIIntroducingntroducing thethe PP--CSCF, ICSCF, I--CSCFCSCF

The P-CSCF is the 1st SIP proxy seen by the terminal

It controls the bearer plan via COPS protocol

It adjusts the SIP message (e.g., compression) and forwards it to the I-CSCF of the home

network The operator may have several S-CSCFs (e.g., offer

segmentation)

So it introduces, the I-CSCF SIP proxy as the entry point of its


network

also used as the entry point for calls from other operators

Home Network

Visited Network

P-CSCF

S-CSCF (consumers)

S-CSCF (enterprises)I-CSCF

HSS

John is calling Betty who hasJohn is calling Betty who has


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g yg y

a legacy phonea legacy phoneIntroducing the MGCF and the MGWIntroducing the MGCF and the MGW

At the border of the IMS network with the phone network,an adaptation is necessary.

The MGCF handles the control for the 2 worlds and drivesthe MGW (Media gateway)

controls circuits and MGW much like a VoIP softswitch


MGCF

MGW

H248 MGCP,Megaco

SIPLegacy Call control (SS7)

Phone transmission

Internet PSTN/PLMN network

RTP


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A Typical Example of an IMS CallA Typical Example of an IMS Call


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A Typical Example of an IMS CallA Typical Example of an IMS CallNetwork XNetwork X Network YNetwork Y

P-CSCF

I-CSCF

I-CSCF

S-CSCF

S-CSCF

HSSHSS

ASAS


User B

DSL/Cable ModemDSL/Cable Modem

DSLAM/CMTS

RNC

GGSN

Network Z (UMTS/GPRS)Network Z (UMTS/GPRS)

User A

SGSN

GRXGRX

P-CSCF


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The Signaling PlaneThe Signaling Plane


SIP functionalitySIP functionality


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SIPs main goal is to deliver asession descriptorto auser at his/her/its location A session descriptor contains the information needed

for a remote user to join the session IP address and port

Codecs

SDP (Session Description Protocol) A (possible) text-based way to describe the media session



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SIP entitiesSIP entities


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SIP entitiesSIP entities

Registrar

User Agent SIP endpoints handled by users (also automatically, based on user-

defined rules)

Proxy server


Usually is co-located with the registrar, and always uses the informationon the registrar (through a location server) to route the calls

Forking proxy Parallel or serial forking in the message routing

Redirect server For routing, but no message delivery

SIP transactionsSIP transactions


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Transaction structure

A request from the client

Zero or more provisional responses from the server

A final response from the server

Each message begins with a start line

Request line (in a request)


e.g.: INVITE sip:[email protected] SIP/2.0

Status line (in an answer)

e.g.: SIP/2.0 180 Ringing

Start line

One or more headers (name:value)

---------EMPTY LINE ---------

Message body (OPTIONAL)

SIP message format

Method Request URI Protocol version

Protocol versionStatus

code

Human

code


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PrerequisitesPrerequisitesTwoTwo--phase registrationphase registration


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TwoTwo phase registrationphase registration

Inbound/Outbound

Offline subscription

Login to the


Fixed Proxy

Online registration

IP access net

DHCP or

Lower level

mechanism


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PP--CSCF discoveryCSCF discovery


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The IMS terminal has to discover the IP address of theP-CSCF

The procedure can be

stand alone (DHCP+DNS)

integrated with the access to the IP (e.g., with the PDP context)


IMSIMS--level registrationlevel registration


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The user requests authorization to usethe IMS

The IMS authenticate and eventuallyauthorize the user

SIP REGISTER is mandatory


DIAMETER is used by the CSCF to contact the HSS

For security reasons, the user is challenged to show itsidentity this require two SIP REGISTER messages

IMSIMS--level registrationlevel registrationThe HSS tells the I-CSCF whether a S-CSCF

was already allocated to the user.

If not, I-CSCF will choose based on

capabilities notified by HSS in the UAA


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UAA:UserA

uth.Ans.

MAA:Multi

lediaAuth.Ans

SAA:ServerAssignmentAns.

p y

Without

authentication

DL User Auth

vector


UAR:UserAuth.

Req

MAR:Multim

ediaAuth.Req

SAR:ServerA

ssignmentReq.

Challenge the User

DL User

Profile

authentication

vector included


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Basic Session SetupBasic Session Setup


SessionSession


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setupsetup


many messages

involved in the setup

Different

planes/layers

mediasignalingCANcore

Session setup (Session setup (contedconted))


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