End-to-End QoS in LTE


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Determine the required delivery characteristics of a packet stream and how a Traffic Management (TM) module can offload compute-intensive tasks. Hear more about the latest innovations in both DPI & TM solutions.

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End-to-End QoS in LTE

  1. 1. Welcome! Real Implementation Challenges of LTE Network Equipment: April 12 Exploring the Trade-offs and Deploying LTE Small Cells: Interference Solutions Mitigation Solutions May 17 Building EPC Systems June 14 The LTE Service Layer July 12 End-to-End QoS in LTE To view past webinars: http://www.radisys.com/recent-webinars/ Radisys Corporation Confidential 1
  2. 2. End-to-End QoS in LTEDelivering the Appropriate Customer Experience Speakers: Larry Greenstein – Sr. Product Line Manager Dikshit Sawhney – Software Architect James Radley – Sr. Architect July 12, 2012 Radisys Corporation Confidential 2
  3. 3. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 3
  4. 4. End-to-End LTE Infrastructure From Radio Access to Media ProcessingRadio Access Network Evolved Packet Core Policy Control IMS IP Policy & User Mobility Multimedia Equipment Charging Management Subsystem Routing Home eNodeB Entity Function Application Media Server Resource Function User Policy & Equipment Charging Internet Enforcement Function eNodeB LTE Security Serving Packet Gateway Gateway Gateway  Macro  Small Cells  10G  40G ATCA  Dumb  Smart Pipes  Audio  Video Conf  60+ Customer Wins ~40% ATCA Market Share  Traffic Management  ~65% Market Share Radisys Corporation Confidential 4
  5. 5. Usage Up, Revenue DownQoS to the Rescue Capacity Mind The Gap Revenue vs. Traffic Growth Traffic Revenues & Traffic Gap Widening Voice Era Revenues Data Era  Traffic Doubling every 12 months  Must Increase ARPU  VideoTextOperators’ Albatross =  Must Lower Cost per Bit Source: Cisco VNI Source: Heavy Reading Radisys Corporation Confidential 5
  6. 6. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 6
  7. 7. LTE QoS: Fundamental Need  Why QoS? • Finite network resources – Radio spectrum limited – Backhaul bandwidth limited – Network congestion has to be managed • Users (applications) need a variety of services – Guaranteed bit rate (voice) – High speed throughput (video) – Priority service (emergency call) Radisys Corporation Confidential 7
  8. 8. Policy Control and Charging (PCC)  Policy Management • Operator control over network usage • Control the level of service provided and charge accordingly – Superior performance for the customers that pay for it – Enforce limits or restrictions based on customer subscription – Dynamic service level adjustment enhances QoE – Offer attractive options to gain market share – Restrict content based on subscription or local laws Radisys Corporation Confidential 8
  9. 9. Where QoS Happens in the Network Home AF IMS Subscriber Application Server Function Network Policy & Mobility Charging Management Rules Entity Function Internet eNodeB Serving PDN Policy & Charging UE Gateway Gateway Enforcement FunctionWeb Radio S1 S5Email Bearer Bearer Bearer Service Data FlowsVoice Packet Filters Radisys Corporation Confidential 9
  10. 10. Poll Question 1  The top QoS concern of operators and equipment manufacturers is: A. Adding value and monetizing it (increase revenue) B. Efficient use of network resources (reduce cost) C. Ensuring customer satisfaction D. Compliance with regulations Radisys Corporation Confidential 10
  11. 11. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 11
  12. 12. Agenda – QoS Specifics  QoS Functions in Control & User Plane  Policy & Charging Control Architecture  EPS Bearers and Service Data Flows  QoS Attributes  Example PCC Call Flow Radisys Corporation Confidential 12
  13. 13. QoS Functions  Control Plane • Admission control maintains information about all available resources of a network entity and takes decision to allow a new session or not based on the current resource usage. • Subscription Control checks whether or not a user is entitled to use the requested service with the specified QoS attributes • Service Management coordinates the functions of the control plane entities during setup, modification and deletion of the EPS bearers • Translation function converts between the EPC QoS parameters the various protocols for service control of interfacing external networks e.g., UMTS to IP QoS parameters mapping Radisys Corporation Confidential 13
  14. 14. QoS Functions  User Plane • Mapping function provides each data unit with the specific marking required to receive the intended QoS at the transfer by a bearer service, e.g., DSCP marking at the PDN-GW • Classification function assigns data units to the established services of a user according to the related QoS attributes if the user has multiple bearer services established • Resource Manager distributes the available resources between all services sharing the same resource based on the QoS, e.g., scheduling, bandwidth management, and power control for the radio bearers • Traffic Shaping provides conformance between the negotiated QoS for a service and the arriving data traffic Radisys Corporation Confidential 14
  15. 15. QoS Functions in different NetworkElements TE MT RAN CN EDGE Gateway Ext. Netwk. Class. Class. Cond. Cond. Cond. Mapping Mapping Mapping Resource Resource Resource Resource Resource Local BS External BS Manager Manager Manager Manager Manager RAN Access Network RAN phys. BS BB network service Service Radisys Corporation Confidential 15
  16. 16. Policy and Charging Control (PCC)Architecture Subscription Profile AF Repository (SPR) Online Sp Rx Charging System (OCS) Policy and Charging Rules Function (PCRF) Gxx Gx BBERF PCEF Gy Gz Offline Charging System Gateway (OFCS) Radisys Corporation Confidential 16
  17. 17. PCC Network Elements  PCRF (Policy & Charging Rules Function) • PCRF is the central node in the policy and charging control architecture; it keeps a DB of PCC rules in SPR and supports flow-based charging and policy (QoS) • Interworks with other network elements via the Diameter protocol  SPR (Subscription Profiles Repository) • DB of PCC rules; can be co-located with HSS or PCRF • A PCC rule consists of traffic filters to map Service Data Flows (SDF) to EPS Bearers, QoS and charging related parameters  PCEF (Policy & Charging Enforcement Function) • The enforcement part of the policy architecture • Main functions include DPI, traffic shaping, etc. • Typically co-located with a PDN-GW  BBERF (Bearer Binding and Event Reporting Function) • Bearer Binding and Event Reporting Function • Use PCC rules to map SDFs to EPS bearers; logical function of PDN-GW Radisys Corporation Confidential 17
  18. 18. Relationship between SDF Flows andEPS Bearers  QoS is defined on a per EPS Bearer basis • An EPS bearer is an end-to-end connection between the service user and PDN-GW. It consists of EPC Bearer, S1 Bearer and Radio Bearer • Service data flows sharing the same QoS/IP address use the same EPS bearer. Examples of SDFs include FTP, HTTP, VoIP IMS traffic etc. • Traffic filters at UE and PDN-GW determine which traffic flow gets mapped to which EPS Bearer Radisys Corporation Confidential 18
  19. 19. EPS Bearers  GBR vs. Non-GBR Bearers • GBR require resources to be reserved in every node in the EPS through which data packet traverses; requires efficient admission control methods • Non-GBR specifies best-effort service – useful for background, interactive traffic classes such as email, web browsing, file download, etc.  Dedicated vs. Default Bearers • Default bearer (one per UE IP) setup on Attach provides basic connectivity – best effort QoS, non-GBR • One or more Dedicated bearers setup for specific QoS requirements – can be GBR or non-GBR Radisys Corporation Confidential 19
  20. 20. QoS Attributes  Maximum bit rate (MBR, AMBR) • Maximum allowable bit rate for a GBR bearer or Aggregate Maximum bit rate for all non-GBR bearers combined • AMBR defined on per APN and per subscriber basis  Guaranteed bit rate (GBR) • Guaranteed by the network via Admission Control • Can’t exceed MBR in Release 8 Radisys Corporation Confidential 20
  21. 21. QoS Attributes, continued  QoS Class Identifier (QCI) • Defines packet forwarding treatment at each node, e.g., queuing thresholds, scheduling weight, admission control priority, etc. • Nine standardized QCI values with different characteristics – GBR/non-GBR, priority, delay sensitivity, and packet error loss rate e.g., QCI 1 is defined for a GBR bearer for conversational or voice traffic  Allocation and Retention Priority (ARP) • “Allocation” dictates control plane behavior during bearer setup, modification procedures, etc. • “Retention” determines relative priority of a bearer over other bearers in case of congestion • Fifteen different ARP (priority) levels – 1 being the highest priority Radisys Corporation Confidential 21
  22. 22. Call Flow - PCRF Interaction DuringDedicated Bearer Setup UE eNodeB MME Serving GW PDN GW PCRF (A) 1. IP-CAN Session Modification 2. Create Bearer Request 3. Create Bearer Request 4. Bearer Setup Request / Session Management Request 5. RRC Connection Reconfiguration 6. RRC Connection Reconfiguration Complete 7. Bearer Setup Response 8. Direct Transfer 9. Session Management Response 10. Create Bearer Response 11. Create Bearer Response 12. IP-CAN Session Modification (B) Radisys Corporation Confidential 22
  23. 23. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 23
  24. 24. PCEF and DPI  The Policy & Charging Enforcement Function (PCEF) cannot rely on coarse-grained assumptions about flow types • Subscriber to be identified and associated policy profile retrieved • DPI of multiple initial packets in every new stream required to correctly determine service signature • Fragmented packets may need to be temporarily reassembled for analysis before forwarding on in original pieces.  Policy engines need to be tailored to the unique requirements for the confluence or regional usage patterns and characteristics of installed network • Enforce only those policies which matter and with no more precision than necessary Radisys Corporation Confidential 24
  25. 25. User Specified Profiles  The win-win cost / benefit advantage of user-elected usage profiles make this a compelling technology  My ideal profile may not be yours, e.g.: • On-time delivery of VoIP packets above all else • Anything over VPN should get preference over everything below • Favor web browsing traffic – But no need to hurry advertisements • Don’t prejudice email traffic unless you must • Feel free to throttle video (I don’t care) – unless I’m on Wi-Fi • Please block software updates when I am roaming – Particularly difficult: how does an operator export preference profiles? Radisys Corporation Confidential 25
  26. 26. Typical Flow Management Architecture Stage 1 Stage 2 Stage 3 FlowDe-tunnel Extract flow ID Table Stage 4 Known Flow Apply Rule Update flow table Application processing ~ 90% of packets - Load Balance Stage 5 - Rate shaping - Monitoring / Analysis Unknown Classification Engine - Video conversion - Policy enforcement Low level Update flow table ~ 10% of packets Stage 6 Custom Assign new flow to appropriate target appln resourceStateful, application aware, load balancer is key for traffic steering applications Radisys Corporation Confidential 26
  27. 27. Packet Flow Analysis New packets arriving enable additional detail to be extracted from flow …approx 10% packets HTTP GMAIL Metadata …Username …Email titleServer Load …Content API State Machine User Application Add new entry by default… Application adds …or wait for application Buffered table entry & rule API Packets Apply Rule e.g. put into correct priority queue Radisys Corporation Confidential 27
  28. 28. Possible Mapping of LTE QCI:Single Subscriber Priority 1QC5Signaling Commit WFQ Flow Shaper Priority 2 CIRQC1 Commit/Excess/RedVoice <Commit Flow Shaper GreenQC2 Commit/Excess/RedVideo Strict Priority Priority Mapper Class Shaper Flow Shaper ExcessQC3 WFQ Commit/Excess/Red Priority 4 CIRVideo <Excess Yellow Flow ShaperQC4 Commit/Excess/RedGaming >ExcessQC6 RedGaming Non-CIRQC7 Video Priority 3 WFQQC8 TCP Radisys Corporation Confidential 28
  29. 29. Example: Traffic Management Assist  NPU mezzanine provides 80Gbps NPU for PP81 to accelerate blade performance  Broad potential applications • Load Balancing • Ingress Traffic Management • Egress Traffic Management • IP Defragmentation • Packet Normalization • Statistics Acceleration  Efficient Software Interface for low overhead on XLP Radisys Corporation Confidential 29
  30. 30. Traffic Management Connectivity 4 DIMM PCIe x8 XLP832 RTM PCIe x8 / ILA ICI TM Mezzanine Up to 120Gbps XLP832 4x10G 120G PCIe x1 4 DIMM 4x10G Fabric Buffer Memory 200G Fabric TM Unit Broadcom Up to 5 ports Stats Trident switch Memory 8 x10G 5 x 40G (fabric ch0-4)  TM connects into main Ethernet switch to allow for flexible packet routing configurations  TM managed over PCIe by XLP Radisys Corporation Confidential 30
  31. 31. Traffic Management Key Features  Network processors can be used to add a number of Traffic Management (TM) capabilities to a DPI blade: • Egress traffic shaping with 256k queues and 5 levels of hierarchy • Ingress packet filtering and denial-of-service prevention • Flow-based load balancing across associated processors • IP Defragmentation and packet reassembly  An NPU is designed to maintain the huge array of per- Class of Service (CoS) queue counters and timers required to provided fine-grained scheduling • Weighted Round Robin (WRR) • Deficit [Weighted] Round Robin (DRR / DWRR) • Weighted Random Early Detection (WRED) • Committed Information Rate / Committed Burst Size (CIR / CBS) Radisys Corporation Confidential 31
  32. 32. Poll Question 2  To adequately classify an LTE GTP-U packet stream for QoS purposes, what degree of analysis is required? A. QoS can be defined with a straight mapping based upon assigned Tunnel Endpoint IDentifer (TEID) B. Simple mapping from tunneled L3/L4 attributes (L4 port number, DiffServ, Subscriber’s IP address, etc) C. Parsing initial packets with a limited set of decision tree rules to differentiate broad class of service (e-mail, video, http, etc.) D. Signature analysis on early packets until a precise recognition is made E. Ongoing signature analysis in case the nature of the flow changes F. Can’t do any useful DPI because packets are encrypted Radisys Corporation Confidential 32
  33. 33. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 33
  34. 34. Conclusions LTE QoS Benefits • User: Assures service delivery meets expectations • Operator: Can offer a wide variety of services and monetize them Embedded LTE QoS Challenges Wireless • Requires coordination across all Infrastructure business units to plan and execute Solutions LTE QoS Opportunities • LTE presents a tremendous Unmatched opportunity for mobile services to Products & grow faster than at any time in the Expertise past Radisys Corporation Confidential 34
  35. 35. Today’s Agenda  Market Dynamics  LTE QoS Fundamentals  LTE QoS Methods and Mechanisms  Policy Enforcement  Conclusion  Q&A / Wrap-up Radisys Corporation Confidential 35
  36. 36. Q&A Contact us! Larry: larry.greenstein@radisys.com DS: dikshit.sawhney@radisys.com James: james.radley@radisys.com For more information on our products, visit: www.radisys.com ̴ Please fill out our short survey ̴ Enter in your mailing address to receive a Free Trillium Poster! THANK YOU FOR ATTENDING! Radisys Corporation Confidential 36