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Explore the convergence of IMS and QoS for enhanced service delivery. Understand QoS basics, application requirements, models, and implementation in IMS architecture with a focus on policy management.
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IMS & QOS IMS Alphabet Soup and the need for Unified Policy Management Matt Tooley CableMatrix Technologies, Inc.
Agenda • Review of Quality of Service (QoS) • IMS + QoS in theory • Policy Management • IMS + QoS in the real world • Putting it all together • Summary
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
Growing need for QoS Video Conferencing/Telephony IPTV Latency/Loss Sensitivity Voice Streaming Video More exciting – weigh heavily on the network Utilitarian – weigh lightly on network Console Gaming Game Download Low-end Gaming Legacy Internet Services Video Download Music Download Bandwidth Consumption
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
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 Requirement
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
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
QoS Framework for NGN Application Function IMS Switching Core SIP SIP Policy Manager QoS Control Core IP Network Access Nodes IP Routers CPE
Other IP/ IMS network Control Plane Traffic Plane IMS Architecture IMS HSS Mm I-CSCF Cx I-CSCF Cx Mw S-CSCF Mk P-CSCF Mr Mi MRF Mg Go Gi Gq BGCF Mj MGCF Gi UTRAN SGW IMS- MGW PDF Mn Go Gi Legacy/ PSTN UE SGSN GGSN
PSTN PLMN IMS Architecture - Simplified SERVICE PLANE SCIM (Service Broker Platform) QoS MRFC S-CSCF HSS I-CSCF HLR CONTROL PLANE P-CSCF BGCF MGCF PDF RAN MGW MGW MRFP Node B RNC GGSN BTS SGSN BSC Intranet/Internet WLAN TRANSPORT PLANE
Policy Decision Decisions concerning Service Based Local Policy Policy Set - up info P - CSCF Policy Gq / Gq’ QoS - related Application Decision application - level Function Function parameters ( e . g . SDP ) Policy Policy Enforcement Decisions Diffserv , Intserv QoS Go parameters , etc Access GGSN , CMTS , UE BRAS , ASN - GW Network 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
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
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
IMS based QoS (3/4) SDP Inspection UE P-CSCF S-CSCF AS SDP AS checks SDP and request confirmation for resource reservation at the endpoint SDP inspection performed based upon Local Policy or User Subscription SDP inspection performed based upon Local Policy
5 Authorization 3 Service Token Information P - CSCF Application 2 QoS Function negotiation 1 – SDP from UE 1 4 – QoS Authorization Policy Decision Function 6 SDP from UE 2 7 QoS Authorization and Commit when bearer channel authorization requested GGSN , CMTS , UE 1 UE 2 BRAS , ASN - GW IMS based QoS (4/4) Media Path
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,…
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: ??? Alphabet Soup
CSCF Session Control Plane ( SIP ) PDF Resource Control Plane UMTS IMS & QoS Ideal Case
Session Control Plane ( SIP ) CSCF PDF PDF PDF Resource Control Planes DSL / WiMAX 3 G Cable IMS & QoS Real World
Session Control Plane ( SIP ) CSCF PDF PDF PDF Resource Control Planes DSL / WiMAX 3 G Cable 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
Session Control Plane Application CSCF Function ( SIP ) ( non - SIP ) Resource Control Plane Policy Server / Policy Decision Function Cable / WiMAX 3 G DSL Transport Plane IMS & QoS Real World – The Solution
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
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-You Matt Tooley CTO CableMatrix Technologies, Inc http://www.cablematrix.com mtooley@cablematrix.com (847) 294-0600
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 Acronyms