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An Analysis of the UMTS Control Plane

Michael Barry, Dimitra Vali, Dorgham Sisalem,michael.barry@ul.ie

p1111@eurescom.de

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Introduction

• Eurescom P1111• SIP and NGNs• Quality Assurance and SIP• Implications for UMTS

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P1111 Mission Statement

“Demonstrate the capabilities of SIP as the future of telecom session control. With support for service creation and delivery mechanisms; quality and security assurances; user and terminal mobility; and interworking with existing networks and services, SIP provides the ideal enabler for Next-Generation Networks.”

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Eurescom P1111 Definition and promotion of an open software

platform for value added services. Deployment of existing and new services over the

Internet using a distributed SIP based platform Develop an understanding of dynamic behavior of

NGNs and SIP Investigate interworking options to existing

telecom networks Recommendations to PNOs about SIP for Next

Generation Networks

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Task 3 - SIP and NGNs

• Whats an NGN– Any hybrid packet/circuit switched network providing

advanced telecom services

• NGNs will at a minimum provide the functionality and services of existing PSTN, 2G and IP networks– Many features such as QoS, Mobility and Security which are

designed into current networks must exist in the NGN world– SIP will be central to controlling and interacting with the

network on behalf of the user

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Task 3 - Aims

• Explore Different Aspects of NGNs– Mobility– Security– QoS– Service Delivery

• How is SIP a service enabler in these areas– Experimental Approach

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Example - SIP in UMTS

Services Network

IP Multimedia NetworkIP Multimedia Network

RadioAccess

Network

RadioAccess

Network

UMTS Core Packet Transport NetworkUMTS Core Packet Transport Network

CSCF

MGCF

Iu

MRF

HSS

SGSN GGSN External

Network

MGW

• Internet Multimedia (IM)• CSCF is a SIP node

– SIP Proxy• Incoming Call Gateway

• Call Handling

• Address Handling

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Example - SIP in UMTS

Services Network

IP Multimedia NetworkIP Multimedia Network

RadioAccess

Network

RadioAccess

Network

UMTS Core Packet Transport NetworkUMTS Core Packet Transport Network

CSCF

MGCF

Iu

MRF

HSS

SGSN GGSN External

Network

MGW

• Mobility Support– User Mobility in CSCF/HSS

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Example - SIP in UMTS

Services Network

IP Multimedia NetworkIP Multimedia Network

RadioAccess

Network

RadioAccess

Network

UMTS Core Packet Transport NetworkUMTS Core Packet Transport Network

CSCF

MGCF

Iu

MRF

HSS

SGSN GGSN External

Network

MGW

• Mobility Support– User Mobility in CSCF/HSS

• Security– In co-operation with HSS

– Firewall Management

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Example - SIP in UMTS

Services Network

IP Multimedia NetworkIP Multimedia Network

RadioAccess

Network

RadioAccess

Network

UMTS Core Packet Transport NetworkUMTS Core Packet Transport Network

CSCF

MGCF

Iu

MRF

HSS

SGSN GGSN External

Network

MGW

• Mobility Support– User Mobility in CSCF/HSS

• Security– In co-operation with HSS

– Firewall Management

• QoS Support– Control relationship with

MGCF

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SIP and QoS

• Allow users to specify and negotiate QoS in a peer-to-peer manner

• Interact with Network to provide end-to-end QoS on a per-session basis

• Allow in-session renegotiation of service quality

• Using IntServ and DiffServ based QoS Mechanisms

• Interwork with other QoS solutions, e.g. UMTS

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SIP and QoS

• Signalling options– Session Setup + Signalling vs Assured Session

Setup

• Session Setup + Signalling– First establish a SIP Session. Then look for

network resources for QoS

• Assured Session Setup– QoS requirements setup and negotiated during

session establishment

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SIP and QoSRSVP Experiment

• WHY RSVP– Supports exchange of QoS parameters between

end hosts• TSpec, RSpec

– RSVP signalling is transparent between intermediate nodes

– RSVP signalling can originate either from the end-host or the SIP GW

• Need access network signalling for this

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SIP and QoSRSVP Experiment

SIP messages

SIP messages

Authorization (COPS)

SIP messages

SIP messages

SIP messages

SIP messages

Admission control (COPS)

Admission control (COPS)

Authorization (COPS)

RSVP Router

SIP User Agent 1RSVP enabled

SIP User Agent 2RSVP enabled

RSVP messages,

data path

RSVP messages,

data path

Policy Server 1

Policy Server 2

User Agent SIP Proxy 1

User Agent SIP Proxy 2Gateway

SIP Proxy 2Gateway SIP Proxy 1

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SIP and QoSRSVP Experiment

SIP UserAgent1RSVP enabled

User Agent SIP Proxy 1

Gateway SIP Proxy 1

Gateway SIP Proxy 2

User Agent SIP Proxy 2

SIP UserAgent2RSVP enabled

RSVP Router

RSVP PATH

INVITE

INVITE INVITE

INVITE

INVITE

RSVP RESVRSVP RESV

RSVP PATH

RSVP RESV CONFIRM

RSVP RESV CONFIRM

180 RINGING

180 RINGING 200 OK

200 OK

Data Exchange

180 RINGING

200 OK

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SIP and QoSOpen Issues

• Set of Generic SIP/SDP extensions to describe QoS reuirements

• QoS in DiffServ Networks– Role of Admission Control– Use of network/user policy control

• In-Session (re)negotaiation of service– Due to changing conditions – multiparty– Reinvite message

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Future Work• Impact in UMTS

– Interwork with UMTS QoS levels– Common mechanism to define QoS – SLA,

TSpec, RSpec– End use – CSCF relationship– Interacting with other Networks

• SIP and Security– Firewalls, NATs

• SIP and Mobility

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Future Work

• Set of Generic SIP/SDP extensions to describe QoS reuirements

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Key Results Assessment of SIP for new

telecommunications services over IP Networks Promotion of the idea of a SIP Service Platform Demonstration of service development

according to the SIP approach Understanding of dynamic behavior of NGNs

and SIP Recommendations to PNOs about SIP for Next

Generation Networks

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SIP and NGNs

HA

FA

QoS GW

RC

BB

AAA

SIP based Services Network(3GPP IM ++)