June 2006

Roles of Session Border Roles of Session Border Controllers in IMS NetworksControllers in IMS Networks

CANTO - June 2006

Agenda

Session Border ControllersWhat is an SBC?Why are Service Providers using them today?

IP Multimedia Subsystem (IMS)What is IMS?Why are Service Providers evolving to IMS?

SBC’s in IMS NetworksWhat functions do they provide in the IMS Network?How will SBC’s evolve within the IMS architecture?

ConclusionsSummaryReferences

SBC Role Today - ‘Session Aware’

Core SIPInfrastructure

SessionBorder

Controller

SIP NormalizationIPv6 / VLAN

Topology Hiding

DoS Prevention

Firewall/NATLoad Balancing

Session QoSSimplify, Protect and Offload

AccessNetwork

PeeringNetwork

Firewall/NAT Traversal

Firewalls/NATs

SIP Services:• SIP Proxy• Application Server• Media Server

SessionController

SIPEndpoints

Solves Firewall/NAT traversal from within the service provider network – Do not have to replace existing firewalls/NATs

Offloads SIP Proxy – up to 20,000 re-registers a second

AccessNetworks

Sim

plify

& O

ffload

DoS Attack Prevention

Provides protection against Denial of Service (DoS) attacks in the form of SIP signalling

Provides policing of individual media sessionsExample – Users Signal G.711 (voice) call, but transmit video RTP session -> Maintaining QoS for other users

AccessNetwork

CoreNetwork

SIPServices

SessionController

Pro

tect

Topology Hiding

Provides protection against Denial of Service (DoS) by hiding internal IP addressing

Removes sensitive IP addressing and domain names from SIP headers and SDP

AccessNetwork

SIPServices

SessionController

Pro

tect

PeeringNetwork

200.2.x.x

17.3.x.x

110.5.x.x

What is IMS?

IMS = IP Multimedia Subsystem

IMS is a network architecture that uses SIP to provide multimedia services over IP

IMS is a technology which provides fixed/mobile network convergence

Layered architecture that separates transport (media), control (signalling) and application functions

What is TISPAN?Telecoms and Internet converged Services & Protocols for Advanced Networks)

Standardize the migration of PSTN networks to a converged network using IMS as the core architecture

Catalyst for IMS Deployment

Who gains from Fixed/Mobile Convergence?

Service Providers

Optimized ‘all IP’ network reduces OPEX

Opens the fixed market’s customers to mobile operators and vice versa.

New revenue streams – ability to charge for services

End Users

Common service set available regardless of the device, the location the access medium

New services available – location based

Applications become more appealing with large subscriber base (Metcalfe’s Law)

Logical separationof applications & network elements• Rapid application development• No vertical silo solutions

IMS Basics…

IMS bringsEnhancements to…

User profiles

Security Roaming

QoS policycontrol

CallControl

SessionDetail

Records

IMS architecture• Functional separation• Open Interfaces

SIP

Based on SIP

IMS Network Characteristics

Access Independent – SIP over IP (Extensions for Mobile)

Open Architecture - Functional Elements Integrated through Open Interfaces

Security at Network Boundaries – Protect IMS Infrastructure

Roaming – User gets same apps in Home or Visited Network

Scala

ble

Arc

hit

ectu

re IMSNetworkAccess

Network

AccessNetwork

Peering IMS

Network

IP

MobileNetwork HSS

HSS

SBC Features

NAT/Firewall Traversal

Protocol Normalization

Protocol Interworking

VLANs

Geographic Resilience

DoS Protection

Rate Limiting

Topology Hiding

Encryption

Policy Enforcement

Policing

Session Admission Control

Legal Intercept

Emergency Call Handling

Call Detail Records

EMS

SNMP

ManagementSecurity

Simplify and Protect PSTN Equivalence

IMS/TISPANRequirement

Within IMS Scope

IMS Architecture with SBC’s

I-CSCF *

P-CSCF

S-CSCF

HSS

BGCF

MGCF

VisitedNetwork

(Originator)

HomeNetwork

(Originator)

GSTN

MG

I-CSCFS-CSCF

HSS

BGCF

MGCF

MG

GSTN

IP-CAN

UE

P-CSCF

HomeNetwork

(Terminating)

PSTN Switches

PSTN Switches

P-CSCF

IP-CAN

UE

IP-CAN

PDF

PDF

Registration

I-CSCF

Session Set up

THIG

SGSG

UE

VisitedNetwork

(Terminating)

• Directs Users to Home Network

•NAT/FW Traversal

•Emergency Call Handling

• HSS service lookup to

select S-CSCF

= SBC

TISPAN architecture – SBC MediaDSL access, WLAN etc

I-CSCF

S-CSCF

HSS

BGCF

MGCF

I BCF

HomeNetwork

(Originator)

GSTN

MG

PSTN Switches

UE

IP-CAN C-BGF

P-CSCF I-BGF

RegistrationSession Set up

= SBC

Media path

• Session Policing• Legal Intercept

• IPv4 to IPv6• Session Admission Control

• DSCP QoS Re-mapping• Topology Hiding

SBC Migration to IMS

SignallingFunctionsSIP

MediaFunctions

ME

GA

CO

/H.2

48

RTP/RTCP

Control Plane

Media Plane

SignallingSBC

MediaSBCMedia

Functions

SignallingFunctions

ME

GA

CO

/H.2

48

MediaSBC

H.2

48

H.2

48

1:N and N:1 models

SCTP (standardized signalling transport)

Signalling compression

Separate signalling & media functions

Independently scale signalling and media

Physically separate the product architecture

Signalling encryption IPSec/TLS

Benefits of Split Signalling & Media

Emerging standards for converged networks (IMS, TISPAN, etc) dictate that separation is required

Media functions can be deployed at the network edge, saving $$ required to backhaul the media traffic to a central location

Physical locations can scale their signalling and media independently – Allows for flexible deployment

Integrated SBC deployments can be upgraded to Distributed configurations at any time with total reuse of hardware

SignallingSBC

MediaSBC

MediaSBC

H.2

48 H.2

48

Signalling

Media

H.2

48 SignallingMedia

Standards Organizations

3GPP - Defined IP Multimedia Subsystem (IMS)http://www.3gpp.org/

ETSI TISPAN - Defining migration to IMS for Wireline networks

http://www.etsi.org/

3GPP 2 - IMS for CDMAhttp://www.3gpp2.org/

MultiService Forum (MSF)http://www.msforum.org/

Open Mobile Alliance (OMA)http://www.openmobilealliance.org/

Internet Engineering Task Force (IETF)http://www.ietf.org

Conclusions

Service Providers are moving to IMS/TISPAN architectures

Service Providers should invest in SBC’s that are forward compatible with IMS

SBC architecture that supports signaling and media separation is required

Today, SBC’s provide a greater set of features, than IMS requirements define

Terminology3GPP 3rd Generation Partnership Project

A-RACF Access Resource Admission Control Function

AUC Authentication Centre

BGCF Breakout Gateway Control Function

C-BGF Access/Core Border Gateway Function

GSTN Global Switched Telephony Network

HSS Home Subscriber Server

IBCF Interconnect Border Control Function

I-BGF Interconnection Border Gateway Function

I-CSCF Interrogating Call Session Control Function

IP-CAN IP Connectivity Access Network

IMS IP Multimedia Subsystem

MGCF Media Gateway Control Function

NAPT Network Address and Port Translation

P-CSCF Proxy Call Session Control Function

PDF Policy Decision Function

QoS Quality of Service

RCEF Resource Control Enforcement Function

SBC Session Border Controller

S-CSCF Serving Call Session Control Function

SPDF Service Based Policy Decision Function

THIG Topology Hiding Inter Network Gateway

UE User Element

June 2006

Thank youThank you

www.newport-networks.com

SBC Signalling Functions

In 3GPP wireless networks the SBC Signalling requirements are:

Proxy Call Session Control Function P-CSCF function

Interrogating Call Session Control Function (I-CSCF)

Can perform Topology Hiding Interconnect Gateway (THIG) functions where required

Contains a Policy Decision Function which can be externalized if required

In TISPAN Converged networks the SBC Signalling requirements are:

An Interconnect Border Control Function when interconnecting networks

In TISPAN the PDF is defined as SPDF (Service based Policy Decision Function)

P CSCF

PDF

IBCF

SBC Signalling Functions

THIG

H.248 Control of Media Plane

Diameter / XML to external policy databases

= 3GPP defined function

= TISPAN defined function

I CSCF

SBC Media Functions

Currently Null function in 3GPP

In TISPAN architectures performs

Access to Core Border Gateway Function (CBGF)

Interconnect Border Gateway Function (IBGF)

I / C BGF

SBC Media Functions

H.248 Control of Media Plane

= 3GPP defined function

= TISPAN defined function

TISPAN architecture with SBC’s

UE

I-CSCF*

I BCF I BCFP-CSCF

S-CSCF

HSS

BGCF

MGCF

I BCF

Home Network(Originator)

GSTN

MG

THIG I-CSCF*

S-CSCF

HSS

BGCF

MGCF

MG

THIG

I BCF

GSTN

IP-CAN

UE

P-CSCFI BCF

Home Network(Terminator)

PSTN Switches

PSTN Switches

P-CSCF

IP-CAN

UE

IP-CAN

PDF

PDF

VisitedNetwork

(Originator)

VisitedNetwork

(Terminating)

Registration

Session Set up

= SBC

SIP-I