IMS & QOSIMS Alphabet Soup and the need for

Unified Policy Management

Matt TooleyCableMatrix Technologies, Inc.

3

Agenda

• Review of Quality of Service (QoS)• IMS + QoS in theory• Policy Management• IMS + QoS in the real world• Putting it all together• Summary

4

Evolving Services

• Entertainment– IPTV, VOD, voice

• Communications– Voice, messaging,

collaboration

• Security– DOS protection, device/user

quarantine

• Managed Enterprise– Dynamic bandwidth allocation

• Fixed Mobile Convergence (FMC)

– Service continuity, application and network-aware QoS

Moving beyond conversational SIP services

5

Growing need for QoS

Late

ncy

/Loss

La

tency

/Loss

S

en

siti

vit

yS

en

siti

vit

y

Bandwidth ConsumptionBandwidth Consumption

LegacyInternetServices

MusicDownload

Voice

GameDownload

IPTV

Streaming Video

Utilitarian – weigh lightly on network

More exciting – weigh heavily on the network

Low-endGaming

Video Conferencing/Telephony

Console

Gaming

VideoDownload

6

QoS 101 – What is QoS?

• Quality of Service (QoS) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program.

• QoS is more than just bandwidth– Delay– Jitter– Priority– Packet loss

7

QoS 101 – Application Requirements

• Voice– Constant bit rate service– Low latency, low jitter– Little or no packet loss– Guaranteed bandwidth

• Streaming Media– Variable bit rate service– Low jitter, low packet loss– Guaranteed minimum bandwidth

• Real-time Gaming– Variable bit rate service– Low latency, low jitter– Low packet loss

• Web Surfing– Best Effort

QoS

Req

uire

men

t

8

QoS 101 – QoS Models

• Differentiated Services (Diffserv)– Provisioned QoS model– Class of services– Prioritized

• Integrated Services (Intserv)– Signaled QoS model with admission control– Flow-based QoS– Parameterized

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QOS Triggering Points – Push, Pull• Push

– QOS pushed from the network

– Network server requests QOS upon service initiation

• Pull– QOS pulled by the

user/user equipment– UE requests QOS

upon service initiation

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QoS Framework for NGN

IMS Switching

Core

Core IPNetwork

CPEAccessNodes

IPRouters

Policy Manager

Application Function

SIP

QoS Control

SIP

11

IMS

UTRAN

SGSNGGSN

UE

I-CSCF

Go Gi

I-CSCF

P-CSCFS-CSCF

Mw

HSS

Cx

Cx

SGWMGCF

BGCF

IMS-MGW

Legacy/PSTN

Mk

Mi

Mg

Mj

MnGi

MRF

Gi

Mr

PDF

Go

Gq

Other IP/IMS network

Mm

Traffic Plane

Control Plane

IMS Architecture

12

BTS BSC

SCIM (Service Broker Platform)

RAN

TRANSPORT PLANE

CO

NTR

OL

PLA

NE

SER

VIC

E P

LA

NE

HLR

PDF

SGSN Intranet/Internet

WLAN

MGW

Node B

RNCPSTNPLMN

MRFC S-CSCF

I-CSCF

P-CSCF BGCF

MGCF

HSS

MGW

MRFP

GGSN

IMS Architecture - Simplified

QoS

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IMS & QoS in Theory

• IMS elements involved with QoS– User Endpoint (UE)– P-CSCF / Application Function– PDF– Edge IP Router

• GGSN, BRAS, CMTS, Base station

AccessNetwork

UE GGSN, CMTS, BRAS, ASN-GW

Policy DecisionFunction

P-CSCFApplication Function

QoS-related application-level

parameters (e.g. SDP)

PolicySet-up info

Gq/Gq’

PolicyDecisions

Go

Policy DecisionDecisions

concerning Service Based Local Policy

Policy EnforcementDiffserv, Intserv QoS

parameters, etc

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IMS based QoS (1/3)

• IMS based QoS– Supports a minimum bandwidth required by a

service based upon PDF’s QoS decision and IP edge node resources

– PDF’s QoS decisions based upon IMS signaling and operator policy rules

• Application level E2E QoS negotiation– End-to-End QoS requirements are negotiated

via SIP/SDP offer/answer model signaling

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IMS based QoS (2/3)

• Mechanism for E2E QoS authorization– SDP Inspection

• SDP media parameters are examined based upon local policy, configuration of operators or user subscription

• If there are any media parameters which are not allowed on the network, CSCF returns a 4XX (Not Acceptable Here) response

• UE, P-CSCF, S-CSCF, and AS perform SDP inspection

– Session Based Local Policy (SBLP) based authorization

• P-CSCF generates the service information from SDP and sends it to PDF

• PDF authorizes the QoS requirements from IMS-Proxy based on operator policy rules

• PDF saves authorization results• PDF authorizes the QoS requirements for IP Edge Node

based upon SBLP

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IMS based QoS (3/4)

UE P-CSCF S-CSCF AS

SDP

SDP Inspection

SDP inspection performed

based upon Local Policy

SDP inspection performed

based upon Local Policy or

User Subscription

AS checks SDP and request

confirmation for resource

reservation at the endpoint

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IMS based QoS (4/4)

Media Path

UE1 GGSN, CMTS, BRAS, ASN-GW

Policy DecisionFunction

P-CSCFApplication Function

UE2

1 – SDP from UE1

2 QoS negotiation

3 Service Information

4 – QoS Authorization

5 AuthorizationToken

6 SDP from UE2

7 QoS Authorization and Commit when

bearer channel authorization requested

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Policy Control Key to Managing QoS

• Business and network orchestration– Subscriber & network policy enforcement

• Media authorization interface– Standard interface between applications and the

network for signaling QoS requests• Real-time service execution

– Dynamic network resource control enables assured delivery of services

• Enhanced network utilization– Intelligent admission control guarantees quality and

maximizes transaction value• Creates new business opportunities

– Charging, partnering,…

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Alphabet Soup

• 3GPP– Release 6: PDF – Policy Decision Function– Release 7: PCRF – Policy Control and Charging Function

• 3GPP2– PCRF – Policy Control and Charging Function

• TISPAN– RACF – Resource Admission Control Function

• CableLabs– PS – Policy Server– PAM – PacketCable Application Manager

• WiMAX– Release 1: PF - Policy Function– Release 1.5: ???

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IMS & QoS Ideal Case

PDF

CSCF

UMTS

Session Control Plane (SIP)

Resource Control Plane

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IMS & QoS Real World

PDF

CSCF

PDF PDF

DSL/Cable

3GWiMAX

Session Control Plane (SIP)

Resource Control Planes

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Problems with this approach

• Requires CSCF to support multiple policy signaling interfaces

• CSCF needs to know information about the transport layer

• QoS Levers– 3G & DSL – Min & Max

bandwidth– Cable & WiMAX

• Shared Media• Min & Max bandwidth• Scheduling –Jitter &

Latency

• No good support for non-SIP based services

• NAT

PDF

CSCF

PDF PDF

DSL/Cable

3G WiMAX

Session Control Plane (SIP)

Resource Control Planes

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IMS & QoS Real World – The Solution

CSCF (SIP)

3G

Session Control Plane

Application Function (non-SIP)

Policy Server/Policy Decision Function

WiMAXCable/DSL

Resource Control Plane

Transport Plane

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Benefits of Unified Policy Management

• CSCF is network agnostic– Does not need to know any transport layer information

• Enables seamless QoS handovers across networks– PDF has visibility of all network resources across all its

networks

• Consistent service levels regardless of network– PDF converts QoS from network agnostic form to network

specific form

• Supports services beyond SIP conversational services– IPTV, internet video, on-line gaming, ….

• Supports Policy Peering for inter-service provider services– Centralized policies minimizes interfaces across peering

points

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Summary

• Keys to success– QoS is required delivering services over IP– Policy management is required for

orchestrating QoS requests for applications– Centralized policy management assures all

applications work equally well regardless of the network

Thank-YouMatt Tooley

CTOCableMatrix Technologies,

Inchttp://www.cablematrix.commtooley@cablematrix.com

(847) 294-0600

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Acronyms• AF – Application Function• AS – Application Server• ASN-GW – Access Service

Network Gateway• BRAS – Broadband remote

access server• BS – Base station• CMTS – Cable modem

termination system• CPE – Customer premise

equipment• DOS – Denial of Service• E2E – End to End• FMC – Fixed Mobile

Convergence

• GW – Gateway• IMS – IP Multimedia

Subsystem• PDF – Policy Decision

Function• PF – Policy Function• QOS – Quality of Service• SDP – Session Description

Protocol• SBLP - Session Based

Local Policy • SIP – Session Initiation

Protocol