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MPLS Support of Differentiated Services (Document: draft-ietf-mpls-diff-ext-04.txt)

MPLS Support of Differentiated Services (Document: draft-ietf-mpls-diff-ext-04.txt). Multimedia Lab. 2000.03.23 Son Nam Rae. Abstract.  Define Flexible solution for support of Diff-Serv over MPLS networks Solution

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MPLS Support of Differentiated Services (Document: draft-ietf-mpls-diff-ext-04.txt)

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  1. MPLS Support of Differentiated Services(Document: draft-ietf-mpls-diff-ext-04.txt) Multimedia Lab. 2000.03.23 Son Nam Rae

  2. Abstract  Define Flexible solution for support of Diff-Serv over MPLS networks • Solution - MPLS network Admin to select how Diff-Serv Behavior Aggregates(BAs) are mapped onto LSP so that BAs can best match the Diff-Serv, Traffic engineering and Fast Restoration objectives within BAs’s particular network. • Combined use of two types of LSPs - LSPs which can transport multiple Ordered Aggregates - LSPs which only transport a single Ordered Aggreage

  3. Overview • Introduction 1.1 Ordered Aggregate(OA) and PHB Scheduling Class(PSC) 1.2 EXP-Inferred-PSC LSPs(E-LSP) 1.3 Label-Only-Inferred-PSC LSPs(L-LSP) 1.4 Overall Operations 1.5 Relationship between Label and FEC 1.6 Bandwidth Reservation for E-LSPs and L-LSPs 2. Label forwarding Model for Diff-Serv LSRs 2.1 Incoming PHB Determination 2.2 Optional Outgoing PHB Determination Via Local Policy and Traffic Conditioning 2.3 Label Swapping 2.4 Encoding Diff-Serv Information into Encapsulation Layer

  4. Overview (cont) 3. Detailed Operations of E-LSPs 3.1 E-LSP Definition 3.2 Populating the ‘EncapsPHB mapping’ for an incoming E-LSP 3.3 Incoming PHB Determination On Incoming E-LSP 3.4 Populating the ‘Set of PHBEncaps mapping’ for an outgoing E-LSP 3.5 Encoding Diff-Serv Information into Encapsulations Layer On Outgoing E-LSP 3.6 E-LSP Merging

  5. Overview Diffserv • Introduction • DSCP & PHB • Conceptual Architecture • Diffserv Components • SLA & TCA

  6. Introduction • Background - Problems of RSVP for IntServ • maintenance of per-flow states (traffic control information, reservation information) • scalability • difficulty of implementation • Integrated Services의 복잡성을 보완하기 위한 논의 • 39th IETF Meeting, August 1997 (David Clark and John Wroclawski) • 40th IETF Meeting, December 1997 (2-bit DS Architecture by Nichols, Jacobson and Zhang) • IETF DiffServ Working Group • 1998년 2월발족 • Chair : Brian Carpenter (ICAIR) Kathleen Nichols (CISCO) • 2000년 3월 현재 : RFC 4개, Working Draft 8개

  7. 차별화 서비스의 데이터 패킷을 MPLS의 LSP로 바인딩 MPLS의 고속라우팅 기능 차별화 서비스 모델을 통한 확장성 있는 서비스 질 제공 Introduction • Differentiated Service - 8bit IPv4 TOS / IPv6 Class Field 이용 (DSCP) • DS Domain 내에서는 DSCP에 따른 차별화된 PHB • draft-ietf-mpls-diff-ext-04.txt

  8. DiffServ Domain marking shaping dropping PHB PHB PHB metering PHB marking marking remarking PHB PHB marking marking Introduction - Diffserv 망 구성 Core Router Edge Router Packet

  9. DSCP(Diffserv Code Point) MPLS

  10. PHB (Per Hop Behavior) • Hop by Hop packet handling discipline • Small set(building-block) of aggregation flow • PHB classes - Default PHB - Class selector PHB - EF(Expedited Forwarding) PHB - AF(Assured Forwarding) PHB • 6-bit DSCP(Differentiated Service Code Point) for PHB

  11. PHB(Per Hop Behavior) • DSCP and PHB are not yet fully standardized • Default (RFC 1821) • IANA Considerations • RFC 2474 • RFC 2597 • RFC 2598 000000 : Best-Effort Forwarding Behavior xxxxx0 : pool 1, Standards Action xxxx11 : pool 2, Experimental or Local Use xxxx01 : pool 3, Experimental or Local Use (Future SA) xxx000 : 8 Class Selector Codepoint xxxyy0 : Assured Forwarding (AFxy) 4 Class * 3 Drop Precedence = 12 DSCP 101110 : Expedited Forwarding (EF)

  12. PHB(Per Hop Behavior) • Default PHB - best-effort service • Class Selector PHB - 상대적인 우선순위 • EF(Expedited Forwarding) PHB - low delay, low loss, low latency, low jitter - top priority-traffic(preemption) - VLL(Virtual Leased Line) service

  13. PHB(Per Hop Behavior) • AF(Assured Forwarding) PHB - 3개의 Drop precedence 갖는 4개의 class(대역폭,버퍼)로 구성 - congestion 상황에서도 drop level을 차별화 해서 minimum rate을 보장 - 각 class는 독립적이고, class간의 관계는 아직불명확

  14. Conceptual Architecture – Edge Router 다른 DS-도메인, DS와 호환하지 않는 망과의 경계역할 패킷들의 코드포인드 변환

  15. Conceptual Architecture – Core Router 코드 포인트에 합당한 PHB를 적용해서 포워딩 역할

  16. Conceptual Architecture – PHB Processor

  17. OF bypass Token Rate Marked Packet Stream marker DP Meter (TBS) Re-mark In-Profile Policer Packet Stream Arrive Out-Profile Dropper Dropped Shaper (SBS) Shape Discard Packet Shaping Buffer Occupancy Overflow Component - Traffic Conditioner

  18. Traffic Conditioner - Classifier • 패킷 header 내의 특정 영역들을 참고로 하여 traffic stream으로부터 특정 packet들을 선택 - 적절한 PHB 선택 •BA(Behavior Aggregate) Classifier - DS filed만을 참고 •MF(Multi-field) Classifier - 다른 여러 개의 field를 참고 - source/destination address field, port field

  19. Traffic Conditioner - Meter • classifier에 의해 선택된 packet들을 TCA의 profile을 기반으로 measuring - in-profile packet인지 out-of-profile인지 판별 • Measuring - Using TSW(Time Sliding Window) • Average rate estimator - Using Leaky Bucket Algo. • Token Bucket Estimator

  20. Traffic Conditioner - Marker • Packet header 내의 DS filed 값을 특정 codepoint 값으로 설정(DSCP) • Recommended codepoint value - Best Effort : 000000(Default value) - EF : 101000 - AF : 4개의 class(3bit)와 3개의 drop precedence에 따라서 다름(12가지) TCM(Three Color Marker)

  21. Traffic Conditioner – Shaper/Dropper • Shaper traffic stream을 traffic profile에 맞추기 위해 하나 또는 여러 개의 packet들을 지연 • Dropper(Policer) buffer크기를 조절해서 packet을 drop시켜서 특정한 트래픽 특성을 만족

  22. SLA & TCA • SLA(Service Level Agreement) - 고객과 서비스 제공자 사이의 서비스 계약 - 사용자가 제공받을 포워딩 서비스를 명세 • TAC(Traffic Conditioning Aggrement) - 패킷 분류 규칙과 연관있는 트래픽 프로파일과 측정, 마킹, 폐기, 변형기 규칙등을 명세하고 있는 동의사항

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