Quality of Service for Next Generation Networks

Transcription

1 Quality of Service for Next Generation Networks Amit Mukhopadhyay, Dong Sun Bell Laboraries, Lucent technologies

2 Agenda Introduction NGN and QoS Key Components of QoS Existing Mechanism/Architecture Challenges of End--end QoS Current Standards Developments Summary Appendix 2

3 NGN Architecture Transport Layer Service Layer HFC SIP-based Services DSL/FTTx S/BC S/BC RTSP-based Services Session Session Control Control & User User profile profile IP Core S/BC WiFi/WiMax Applications Applications PSTN/ISDN Emulation PDSN/ GGSN S/BC UMTS/CDMA Other Multimedia Services MGW Internet PSTN Multiple applications supported over a common infrastructure 3

4 The Challenge Other Users Near Future USER User subscribes a variety of interactive and blended applications. Expects enhanced experience. App1 (VoIP) App2 (Multiparty Game) App3 (Teen tracking) QoS1 QoS2 QoS3 Different apps with different QoS requirements Converged networks Resources are shared across multiple users All apps ride over same network. Get same QoS treatment. If congestion occurs end user experience degrades. Application is not attractive. Affects revenues. Quick solution: Provide infinite BW Inpractical and expensive The need for an end--end QoS mechanism. 4

5 Key Components of End--End QoS User Experience Service Service Definition Definition Traffic Traffic Characteristics Characteristics QoS QoS parameters parameters Standards Network Capabilities Network Network Policies Policies Admission Admission Control Control Mechanism Mechanism QoS QoS Implementation Implementation Network Design Network Moniring & Control Traffic Engineering Architecture Architecture Definition Definition Physical Physical Connectivity Connectivity Link Link and and Node Node Sizing Sizing Equipment Equipment Parameter Parameter Setting Setting Node Node and and Link Link Load Load Moniring Moniring Performance Performance Management Management Systems Systems Day/week Day/week time time frame frame Capacity Capacity Augmentation Augmentation Month/quarter/year Month/quarter/year timeframe timeframe - - Strategic Strategic Planning Planning 6 Key Components 5

6 User Experience Example Services and their Characteristics Traffic Class Typical Characteristics Sample Applications Conversational Symmetric bidirectional Delay and jitter very important VoIP, video conferencing, peer-peer gaming Streaming Mostly unidirectional Jitter very important Audio/video streaming, infotainment (weather, traffic etc.) Interactive Asymmetric traffic Sensitive delay, errors Web browsing. server-based gaming, messaging Background Not time sensitive Sensitive errors File transfer, e- mail Different applications have different delay, jitter and bit error rate lerance 6

7 Network Capabilities Policies Subscriber Profiles Preferences HLR/ HSS P-CSCF/ PDF Network Policies UTRAN UTRAN SGSN GGSN Internet Internet Resource availability Policies key component of Next Gen Networks Policy Types: User profiles/subscriptions (sred in HLR/HSS) Network Policies (e.g., codec selection based on network load) Security Services QoS will be impacted by specific policies allowed/selected dynamically Challenge is identify impact of policies on architecture, design, moniring/management 7

8 Network Capabilities Admission Control UMTS Admission Control UMTS SIP Internet Access GGSN Internet Session Control IP Core Media Path PDSN Without call admission control, there will be no QoS, even with MPLS, DiffServ,.. SIP CDMA CDMA Admission Control What: Network decision allow setting up of a new session based on multiple criteria How: Over provisioning no control >> how much overprovision what is the cost? IntServ model reserving bandwidth for every session >> not scalable in core networks End--end probing only an instantaneous view of network >> no control once flow is admitted Pre-provisioned trunks bandwidth partitioning >> not efficient Pre-provisioned trunks with flexible bandwidth >> efficient but complex Admission control with link level measurements >> normalized view of link load End--end Admission Control: Possible day only in some access networks 8

9 Network Capabilities QoS Implementation Mechanisms Classification (e.g., identify VoIP) 802.1d NC, VO, VI, ATM CBR, RtVBR, DiffServ AF, EF, Queuing (e.g., which queue put VoIP packets, what should be the size) Priorities associated with queues (VoIP is high priority), Q0, Q1, Buffer space (short buffer for VoIP avoid queuing delay) Scheduling (e.g., which queue process next and how many packets) Priority Queuing, Weighted Fair Queueing, Order of extracting packets from different queues Proportion of the egress interface bandwidth used by a queue Buffer Overflow Control Random Early Detection (RED) and WRED (Weighted RED) and packet discard Randomizing packet loss, as opposed tail drop For some traffic types, dropped packets are preferable delays Multiple mechanisms and enablers with many details 9

10 Network Design Traffic Characterization MMS Simple Voice Rich Voice Internet Access Some services with high traffic volume in their individual busy hour may not generate high traffic at the aggregate level Location Based Service Intranet Access Individual Busy Hour Traffic Cusmized Infotainment Aggregate Busy Hour Traffic Common resources for aggregate BH, Individual service resources for individual BH 10

11 UMTS Example Release 4/5 Architecture b endpoints Wi-Fi Hotspot Packet Access Network (MPLS) IP/MPLS SIP call over MPLS Iu-CS Wi-Fi GW FA Full IMS PDF Go 3G- SGSN/GGSN MGW Flexent IMS (G)MSC Server H.248 Voice over IP IP/MPLS NOC OMC Billing AAA DHCP DNS Data Center Packet Core Network (MPLS) CGF HA HSS IP/MPLS Voice over IP IP/ATM 3G- FA SGSN/GGSN Internet Intranet Other GPRS/UMTS Networks Packet Access Network (MPLS) IP/MPLS IP RAN RNC PCM PCM MGW Iu-CS Node B PSTN IP RAN RNC UTRAN Node B UE SIP UE UTRAN Each Service Provider may come up with own implementation architecture UE SIP UE 11

12 UMTS Example Bearer Service QoS Set Up Process Generic Packet Service UE RAN SGSN GGSN 1. Activate PDP Context Request Translates the service Establishes a signalling attributes in UMTS connection between the QoS and sends the MS and the SGSN, and request SGSN with allocates resources on QoS paramters SGSN for GTP tunnel 4. RAB Assignment Request 5. Establish Radio Bearers Setup radio channel 6. RAB Assignment Response Setup channel coding and interleaver Setup Perform admission control Map QoS profile RAB QoS Parameters Map QoS profile DiffServ code points for backbone QoS Allocate resources in 2. Create PDP Context Request GGSN Map 3. Create PDP Context Response external bearer QoS The SGSN initiates the (DiffServor RAB assignment procedure RSVP) instruct RNC establish RAB bearer connection 7. Update PDP Context Request 8. Update PDP Context Response 9. Activate PDP Context Accept The radio bearer and GTP tunnel resources are allocated and UMTS connection is is established In In case the QoS attributes have been changed, the SGSN may inform the GGSN about the changed QoS attributes QoS procedures well established in UMTS standards 12

13 UMTS Example Bearer Service QoS Set Up Process with Release 5 IMS Go Interface messages: GGSN requests authorization for context and receives policy enforcement information from PDF. INVITE with SDP offer is received by P-CSCF. UE SGSN GGSN PDF 1. Mapping of SDP parameters in UMTS QoS 2. Activate PDP Req. 3. Create PDP Req. Step 1 - Resource Authorization 183 Session Progress message received from UE2 with SDP offer response. Authorize QoS Resources: Offer-response pair contains sufficient information regarding BW requirements, and media characteristics. The PDF authorizes the necessary resources. An Authorization Token is generated by the PDF. and sent on the 183 Session Progress message (the P-Media-Authorization header) UE1 Activate PDP context request contains binding information: Upon receipt of authorization ken: 1.Authorization Token UE requests a PDP context activation 2.Packet Flow Identifiers for the agreed media. 9. Create PDP Res. 10. Activate PDP Acc. 4. COPS REQ 5. Process authorization request 6. COPS DEC 7. Policy Enforcement 8. COPS RPT PDP context activated. No media is flowing yet and gate status at GGSN is closed. Step 2a -Resource Reservation (Start) UE1 sends UPDATE message UE2 indicating successful reservation of resources. UE2 responds with 200 (OK) message when it has successfully reserved its resources. Approval of QoS commit GGSN P-CSCF PDF OK User answers; UE2 sends 200 (OK) message for original INVITE request. P-CSCF receives the 200 (OK) message. This triggers the Approve QoS commit procedure.. User 2 is being alerted. PRACK ackowledges alerting indication and 200 OK acks the PRACK message. (This is the 3-way handshake for the 180 Message.) Step 2b - Resource Reservation (Complete) 2. PDF approves the QoS Commit 3. DEC 4. GGSN opens the gates 5. RPT OK P-CSCF/PDF approves QoS resources and sends DEC message. GGSN opens the gate. UE1 responds with ACK message and starts the media flow for this session. Step 3 - Approval of QoS Resources Well defined at UMTS layer, but still needs mapping transport layer 13

14 Call-Admission-Control, DiffServ and QoS Quality of Service Call Admission Control (CAC) DiffServ Design and Optimization Call Call Admission Control Control (CAC) (CAC) CAC CAC admits admits a a new new call/service call/service in in the the network network based based on on its its requirements requirements and and network network resource resource availability availability so so that that the the QoS QoS for for existing existing calls/services calls/services is is not not impacted impacted Congestion Congestion affects affects All All Calls Calls - - not not just just new new ones, ones, so so CAC CAC is is needed needed guarantee guarantee QoS QoS CAC CAC helps helps balance balance QoS QoS while while increasing increasing network network utilization utilization DiffServ DiffServ DiffServ DiffServ provides provides a a way way for for the the network network differentiate differentiate among among different different service service types types control control QoS. QoS. QoS QoS characteristics characteristics such such as as bandwidth, bandwidth, latency, latency, jitter jitter and and packet packet loss loss can can be be supported supported at at different different service service levels levels for for different different service service types types Service Service packets packets are are marked marked with with Type Type of of Service Service (TOS) (TOS) priority priority TOS TOS priority priority is is used used differentiate differentiate service service types types CAC gates admission of calls DiffServ maintains QoS for those admitted 14

15 Standards Importance for Multi-Service Networks Identify Standards used implement end--end QoS and identify areas where additional standards would improve design process or implementation Mobile Terminal UMTS/ UMTS/ cdma2000 Network QoS per 3GPP/3GPP2 Gateway Node QoS per IETF etc. External IP IP Network Admission control in UMTS/CDMA2000 is provided by the underlying bearer network. No such mechanism in generic IP networks go across network boundaries Hence the need for Resource and Admission Control Function (RACF) across networks 15

16 RACF in Next Generation Networks Service Stratum Applications Application Functions Application Support Functions and Service Support Functions S. User Profile Functions Other NGN Service Components Service Control Functions Legacy Terminals Legacy Terminals GW GW Access T. User Network Attachment Profile Control Functions Attachment (NACF) Functions Functions PSTN / ISDN Emulation Service Component IP Multimedia IP Multimedia Component &PSTN/ISDN Service Component Simulation Resource and Admission Control Functions (RACF) Other Networks Cusmer Networks NGN Terminals End-User Functions * Access Transport Network Functions Edge Functions Core Core transport Transport Functions Functions Transport Stratum Note: Gateway (GW) may exist in either Transport Stratum or End-User Functions. Resource and Admission Control Functions (RACF) serves as an intermediary between NGN services and transport networks and makes them work independently 16

17 Challenges The Internet pipe provided by SPs does not seem be providing enough revenue growth and is increasingly perceived be a commodity business The very same Internet pipes also enable competirs support services as best-effort IP flows Examples: parasitic VoIP, video telephony, gaming, video streaming, web portals, etc. Demanding applications such as IPTV and VoD need finer granularity (per user/app) of resource control Uniform resource management across diversity of applications (IPTV, VoIP, VoD) and transport types (xdsl, PON, Ethernet, MPLS, IP..) Current pipe model and QoS mechanisms are inadequate support emerging multimedia applications and business model 17

18 Service and Revenue Opportunity Provide personalized service packages based on Date rate (bps), time of day, QoS, Service type (SDTV or HDTV) Capacity consumption (bytes per month) Support occasional in time services, e.g. Temporary service upgrade such as higher bandwidth for limited time such as turbo butn for web browsing/downloading Improve revenue growth QoS Differentiation of SP provided services and parasitic provider s services Usage/capacity Moniring Usage limiting for abusive applications Service aware resource management capability is crucial for SPs succeed in revenue growth and service differentiation 18

19 Unifying Resource Management Unified Application AS TFS Unified Service & Call Control CSCF MGCF MRCF Transport Adaptation, Resource Management & Policy Control??? UMTS/CDMA SGSN UTRAN PCRF? Policy Server GGSN PDSN/HA CDMA RAN Ethernet Router WLAN GW WiFi Access Points Cable CMTS Cable Access Modem Policy Reposiry DSL BRAS DSLAM DSL/ATM Access Modem Unified resource Unified management resource and in admission support of in Fixed support Mobile of Convergence is desirable fixed mobile convergence is desirable 19

20 Target IMS Architecture Application Layer Session Control Layer PSTN MGCF Mobile Network Parlay Application Web Portal Web Services Parlay Gateway (OSA SCS) MGCF IBCF CSCF RACF p-cscf IP/MPLS Core SIP Application IMS IMS (and (and applications) applications) interacts interacts with with a variety variety of of access access and and core core transport transport networks networks via via RACF RACF for for e2e e2e resource resource management management and and QoS QoS control control 802 xx Access DSL Packet Circuit Frame, ATM Ethernet Cable FTTP/C Enterprise VPN 20

21 RACF s Job Services Components (e.g. IMS, Video, Web) Resource and Admission Control Functions (RACF) 802.xx Access DSL Core Transport Core Transport Cable 2G/3G Wireless Dynamic management of a variety of resources (e.g., bandwidth or IP addresses) across varied transport networks different technologies, administrative domains, ownerships achieve end--end QoS and provide border control Service independent mechanism for transport resource management common various applications (e.g., IMS, IPTV and web based service etc.) Admission control for managing network congestion Policy-based arbitration of many--many relationship RACF provides an end--end solution in support of policy based resource management 21

22 Status of Resource Management Standards Work is being done in several SDOs based on similar rationale with different scope ETSI/TISPAN RACS Release 1 limited broadband access networks ITU-T RACF including the access as well as core network, intended for a variety of network technologies e.g fixed and mobile, core transport (e.g. MPLS) 3GPP PCC and 3GPP2 SBBC are doing similar work, but mainly focus on certain wireless access networks with specific technologies ITU-T RACF Release 1 (Recommendation Y.2111) was consented in July 06 Multiple SDOs are embarking on the subject with different scope and focus 22

23 ITU-T RACF Architecture Service Stratum Transport Stratum NACF Ru RACF Service Control Functions (SCF) Rn TRE-FE Rp TRC-FE Rc Rt Transport Functions Rd Rs PD-FE Rw PE-FE Ri Functions in other NGNs Within the NGN architecture, the RACF acts as the arbitrar for resource authorization and allocation between Service Control Functions and Transport Functions. PD-FE/PE-FE covers the decision and allocation of transport resources based on user/network policies such as time of day, priority, etc., TRC-FE covers admission/traffic control, within access and core transport, based on resource availability and QoS requirements PD-FE - Policy Decision Functional Entity TRC-FE - Transport Resource Control Functional Entity PE-FE - Policy Enforcement Functional Entity TRE-FE - Transport Resource Enforcement Functional Entity NACF - Network Attachment Control Functions service-based, transport technology independent service-unaware, transport-technology dependent, network-segment specific RACF isolates specific attributes of services and transport networks 23

24 RACF Highlights RACF provides Transport Resource Management Capabilities Application-driven (network-independent) real-time control Management of transport resources within networks (access or core) and at network boundaries Policy-based authorization and allocation of the resources supporting End-user equipment of varying QoS control capabilities Push and pull models for policy control Multiple transaction models for resource authorization, reservation and commitment A combination of resource management methods based on accounting, measurement and reservation RACF interfaces Service Control Function (e.g. SIP Proxy Server or IMS) allow an Application request resources including: QoS (BW Guarantees, per flow traffic shaping/policing, priority, ) NAPT control and NAT Transversal capabilities Gate control and other border control functions RACF can interface across network boundaries support a variety of business models Addresses Session Border Control Issues Will integrate flow based charging capabilities (future) RACF covers end--end QoS control as well as border control functions 24

25 RACF Key Elements PD-FE Policy Decision Functional Entity Apply network policies resource management requests from Service Control Functions Given an IP address pair and required BW, determine if the given flow can be supported in the network Manage resources along the flow path including NAPT Transversal and Gate Control TRC-FE Transport Resource Control Functional Entity Connection Admission Control Monir network resource utilization and network pology manage path bandwidth availability (reservation and/or monir) PE-FE Policy Enforcement Functional Entity Provides media path functions such as gate control / Firewall NAPT translation and Transversal Per flow policing and QoS-marking Can report usage status Service Control RACF consists of 2 elements: PD-FE and TRC-FE for policy control and resource control 25

26 Key Reference Point Requirements Rs: PD-FE-SCFs For SCFs request transport resource authorization and control Information exchanged: session ID, media descripr, application QoS requirements, priority, gate or NAPT control policy, authorization ken, etc. Rw: PD-FE-PE-FE For PD-FE apply controls PE-FE concerning NAPT, hosted NAT traversal, gating, bandwidth, packet marking, etc. Information exchanged: media descripr, DSCP value, bandwidth committed, bandwidth authorized, authorization ken, gate control command, NAPT control command, usage information, etc. Rt: PD-FE-TRC-FE For PD-FE request resource availability check by TRC-FE Information exchanged: media descripr, bandwidth, other network QoS requirements, network path, etc. 3 main interfaces between service control, PD-FE/TRC-FE and enforcement element 26

27 RACF Example Implementation Architecture Service Control Function (SCF) (e.g. IMS P-CSCF, VoD, IPTV etc) NACF Rn RACF TRC-FE Rc Ru Rt Rw Rs PD-FE Ri Rs PD-FE Rw Rd Rt Rp TRC-FE Rc RACF CPE TRE-FE Access Node Transport Functions PE-FE Border Gateway PE-FE Border Gateway Transport Functions PE-FE Border Gateway Access Network Domain Core Network Domain Each operar administrative domain should have its own PD-FE for policy control Multiple PD-FE and TRC-FE instances are allowed in the same domain PD-FE and TRC-FE can be centralized or distributed, can be a standalone device or integrated with other network devices TRC-FE may control the TRE-FE for aggregation transport QoS The deployment of RACF depends on SP s network configuration, service requirements and business model 27

28 QoS Reference Model for all Standards Bodies Service Stratum Service Control Functions (e.g. IMS) Application Function Transport Stratum NACF/ NASS/ SPR Legends: RACF/RACS/PCC/SBBC Inter-domain Intra-domain Rs/Gq /Rx/Tx Rd/Rq/-/- PD-FE/ Ri/Rq/-/- Rt/Rq/-/- SPDF&A-RACF/ PCRF Ru/e4/Sp/- TRC-FE/ A-RACF/ -* Rc/-/-/- Rp/-/-/- Rw/Ia&Re/Gx/Ty PE-FE/ BGF&RCEF/ PCEF(GGSN/PDSN) Other NGNs ITU-T Rel 1 TISPAN Rel 1 3GPP Rel 7 3GPP2 Rev B Policy Decision Function PD-FE - Policy Decision Functional Entity SPDF - Service-Based Policy Decision Function A-RACF - Access Resources & Admission Control Function (Partial) PCRF - Policy & Charging Rules Function PCRF - Policy & Charging Rules Function (PDF & CRF) Transport Resource Control Function TRC-FE - Transport Resource Control FE A-RACF (Partial) GGSN/SGSN/RNC/Node-B (Embedded, GPRS only) PDSN/PCF/BSC (Embedded, CDMA only) Policy Enforcement Function PE-FE - Policy Enforcement FE residing in network devices (e.g. DSLAM/BRAS, GGSN/PDSN, border gateway) intra- domain BGF - Border Gateway Function (e.g. core Border node) RCEF - Resource Control Enforcement Function (e.g. IP Edge) inter-domain PCEF - Policy & Charging Enforcement Function (e.g. GGSN, TrGW) AGW (PEP Policy Enforcement Point ) (e.g. PDSN) Interface: ITU-T/TISPAN/3GPP/3GPP2 Combined view of ITU-T, TISPAN, 3GPP, 3GPP2 QoS reference models 28

29 QoS Call Flows for Wireline Networks UE UE initiates initiates service service with with media media parameters parameters in in SIP SIP INVITE INVITE P-CSCF P-CSCF verifies verifies that that UE UE is is registered registered and and forwards forwards INVITE INVITE Home Home S-CSCF S-CSCF Home Home S-CSCF S-CSCF verifies verifies that that the the requested requested service service has has a a valid valid subscription subscription session session is is routed routed called called network network elements elements Assuming Assuming all all is is well well in in called called network, network, P- P- CSCF CSCF receives receives SIP SIP 183/ /200 message message P-CSCF P-CSCF checks checks see see if if resources resources are are available available with with PDP PDP (in (in RACF) RACF) - - PD-FE PD-FE pushes pushes QoS QoS policy policy TRC-FE TRC-FE request request QoS QoS RACF RACF can can verify verify request request based based on on local local resource resource availability availability and and push push policy policy down down Service Service Edge Edge Router. Router. 2 P-CSCF S-CSCF 4 Home Network 3 Serving Network Service Edge Router BRAS, CMTS, 5 HSS RACF (PD-FE, TRC- FE, ) 6 Access Network QoS parameters come from either: SDP parameters from the UE Subscription info in the HSS 1 User Equipment IP Endpoints SIP, H.323 and MGCP Interactions among P-CSCF, RACF and network element for E2E QoS H.323 PBX 29

30 Example for UMTS 1 HSS AS P-CSCF Gx+ 7 PCRF PCRF C-TRCF A-TRCF UTRAN/ SGSN GGSN Core Network BGW Other Providers Networks 1. User initiates SIP session. Results in SIP INVITE P-CSCF 2. Based on negotiation between the user equipment and AS, P-CSCF determines how much bandwidth is required for the SIP session 3. P-CSCF issues a request PCRF for Service level QoS authorization 4. User terminal initiates a Bearer Resource Establishment request GGSN 5. GGSN requests PCRF get authorization 6. PCRF checks with A/C-TRCF(s) for resource availability. A/C-TRCF(s) will check resources with the UTRAN, SGSN and Core Network. 7. PCRF sends authorized QoS GGSN for policy enforcement 8. GGSN responds User terminal with Bearer Resource confirmation. Interactions among PCRF, A-TRCF and C-TRCF will lay the foundation for E2E QoS 30

31 Summary Service based, dynamic policy based control of network resources is viewed as crucial the profitability of telecom operars Fine granularity of QoS enables NGN/IMS support a large range of QoS sensitive applications End--end service quality assurance is essential for the fixed mobile convergence in support of anytime, anywhere ubiquius services 31

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33 ETSI TISPAN Resource and Admission Control Subsystem (RACS) (V1.6.8, 12/05) AF Gq NASS I1 e4 RACS Rq SPDF A-RACF Ia Ra Re RCEF BGF CPE Access Node Transport L2T Di Point IP Edge Transport Layer Core Border Node Ds AF - Application Function NASS - Network Access Attachment Functions L2T - Layer 2 Termination CPE - Cusmer Premise Equipment SPDF - Service Policy Decision Function A-RACF Access Resource and Admission Control Function RCEF Resource Control Enforcement Function BGF - Border Gateway Function 33

34 3GPP PCC Architecture AF Subscription Profile Reposiry (SPR) AF AF PDF Gq PDF Sp Rx Policy and Charging Rules Function Online Charging System (OCS) CAMEL SCP Service Data Flow Based Credit Control Go Go Gx PEF PEF PCEF Gy GGSN GGSN Gz GW Offline Charging System (OFCS) R5 R6 R7 34

35 3GPP2 SBBC Architecture (Rev. B) Application Function (e.g., CSCF, AS, etc.) Application Function (e.g., CSCF, AS, etc.) Tx Home Policy and Charging Rules Function Tx Policy and Charging Rules Function CRF PDF Home Network CRF PDP Ty Proxy Policy and Charging Rules Function Serving Network Ty CRF Proxy PDF Proxy TPF PEP Ty Access Gateway (AGW) TPF PEP Access Gateway (AGW) 35

36 Broadband Access DSL PacketCable 1.x PacketCable Multimedia Policy Reposiry LDAP Regional Broadband Networks BRAS Access Network CMS (Gate Controller) COPS Managed IP Network CMTS Application Manager COPS Policy Server COPS Managed IP Network CMTS Access Node (DSLAM) RG NCS Cable Access Network Cable Modem E-MTA Analog Phone Application signaling (e.g. SIP) Cable Access Network Cable Modem S-MTA Primary Line 36