1 / 65

MPLS CoS Clarence Filsfils cfilsfil@cisco.com

MPLS CoS Clarence Filsfils cfilsfil@cisco.com. DiffServ Architecture. Presentation_ID. 2. © 1999, Cisco Systems, Inc. . DiffServ Architecture RFC 2475.

hercules
Download Presentation

MPLS CoS Clarence Filsfils cfilsfil@cisco.com

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MPLS CoSClarence Filsfilscfilsfil@cisco.com

  2. DiffServ Architecture Presentation_ID 2 © 1999, Cisco Systems, Inc.

  3. DiffServ ArchitectureRFC 2475 “This architecture achieves scalability by implementing complex classification and conditioning functions only at network boundary nodes, and by applying per-hop behaviors to aggregates of traffic which have been appropriately marked using the DS field in the IPv4 or IPv6 headers [DSFIELD]. Per-application flow or per-customer forwarding state need not be maintained within the core of the network.” RFC2475 Architecture for Differentiated Services

  4. DiffServ Architecture SLS/TCS 0. Negociation and agreement of an SLS/TCS

  5. DiffServ Architecture 1. Pre-marking in the source domain - per-application/host basis - per-default-gateway basis

  6. DiffServ Architecture SLS/TCS 2. Egress- boundary DS node of source domain applies traffic conditioning to ensure SLS/TCS compliance, hence causing possible re-marking, dropping and shaping

  7. DiffServ Architecture SLS/TCS 3. Classification according to SLS 4. Conditioning according to TCS 5. Assignment to a BA (DSCP setting)

  8. DiffServ Architecture 6. Forwarding according to PHB mapped to set DSCP

  9. DiffServ Architecture SLS’/TCS’ If downstream DS domain support same service provisioning policy, same PHBs and DSCP/PHB mappings Then 7: No-op Else 7’a: SLS’/TCS’ negotiation 7’b: Conditioning according to TCS’

  10. DS fieldRFC 2474 DS field DSCP CU • DS field replaces IPv4 ToS, IPv6 Traffic Class • DSCP = 6 bits : “xxxxxx” notation

  11. EF PHB definitionRFC2598 • EF PHB ensures a minimum departure rate • DSCP: “101110” • EF PHB can be used to build a low loss, low latency, low jitter, assured bandwdith, e2e service through DS domains

  12. AF PHB definitionRFC2597 AF Class 1: 001dd0 AF Class 2: 010dd0 • 4 independently forwarded AF classes • Within each AF class, 3 levels of drop prec01 < 10 < 11, with active Q mgt (RED) • 4 independent capacity management plans AF Class 3: 011dd0 AF Class 4: 100dd0 01: Low Drop 10: Medium Drop 11: High Drop

  13. AF PHB definition (Cont) • Assured Forwarding (AF) PHB group is a means for a provider DS domain to offer different levels of forwarding assurances for IP packets received from a customer DS domain • Olympic Service (Gold, Silver, Bronze) • gold (C1) >= silver (C2) >= bronze (C3) • No quantifiable timing requirements! • delay or delay variation

  14. AF PHB definition (Cont) • Forwarding assurance of an IP packet: • resources allocated to the AF class • local resource allocation config (buffer and link BW) • the current load of that AF class • conditioning at the DS domain edge • the drop precedence of the packet • conditioning at the DS domain edge

  15. Cisco DiffServ Architecture ACLQPPB CARTSNetflow CEF CBWFQFBWFQWRED TS DiffServ Architecture Functional Blocks Classifier Conditioner Forwarding PHB Conditioner MeteringDroppingMarkingAccounting SchedulingDropping Shaping

  16. MPLS/DiffServ: the obvious fit!Scalability! 1000’s of flows Different BA’s of the same FEC follow the same LSP MPLS: FEC toLabel Imposition MPLS: Label Switching DS: PHB based on DSCP DS: Behavior Aggregate’s DSCP Imposition

  17. MPLS/DiffServ: the obvious fit!Enhanced Services 1000’s of flows Per-DSCP FEC would allow for new services (eg. per-CoS TE) MPLS/DiffServ: per-cos per-FEC Label Imposition with DHCP imposition MPLS: Label Switching DS: PHB based on DHCP

  18. VPI/VCI crosstable MPLS/DiffServ: the obvious fit!Enhanced Services PNNI Routing IP Routing ATM Forum Stack MPLS Stack LDP Signalling UNI/NNI Signal. • ATM switch runs IP Routing Protocol and IP QoS functions • “Ship in the Night” Model • More scalability. IP DiffServ intelligence. IP QoS ATMF QoS

  19. MPLS DiffServ Presentation_ID 19 © 1999, Cisco Systems, Inc.

  20. Coloring MPLS Frames • Two methods are possible • Using the EXP bits in the MPLS header and mapping DSCP to EXP • convenient for Frame-based Interface • Mapping a label per-CoS per-FEC • convenient for ATM-based interface

  21. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Using the EXP bits • Copy of Precedence into EXP • Mapping of DSCP into EXP MPLS Domain Non-MPLS Domain IPv4 Packet MPLS Hdr Prec: xyz MPLS EXP: xyz Prec: xyz

  22. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label-inferred CoSdraft-ietf-mpls-diff-ext-01.txt • DSCP to Label mapping Dest-CoS Label P/p CoS1 17 IPv4 Packet P/p CoS2 22 P/p CoS3 25 Prec: xyz P/p CoS4 12

  23. Enforcing PHB’s on non-ATM interfaces Presentation_ID 23 © 1999, Cisco Systems, Inc.

  24. Frame MPLS CoSStraightforward • Same Mechanisms as IP CoS • Link Sharer: IOS CBWFQ • Active Q mgnt and differentiated drop: IOS WRED • AF and EF PHB’s • Class lookup from either • MPLS CoS/EXP • MPLS Label inferred CoS • Undistinguishable from IPv4 DiffServ

  25. Enforcing PHB’s on ATM interfaces Presentation_ID 25 © 1999, Cisco Systems, Inc.

  26. PNNI Routing IP Routing LDP Signalling UNI/NNI Signal. VPI/VCI crosstable IP QoS ATMF QoS ATM MPLS CoSGreat Opportunity! • Peer Model! • IP intelligence at every hop • IP-friendly mech. on ATM switches! • Diffserv instead of per-VC ATM QoS • Superior Resource Utilisation • Simpler Resource Allocation

  27. Two Modes • Multi-LSP in TBR mode • Single LSP in ABR mode • Each has advantage and drawbacks TBR: Tag Bit Rate: ATM service category designed for Differv/MPLS

  28. Multi-VC TBR modeControl Plane ATM LSR • TDP signals up to 4 parallel LSPs for the same prefix • CoS <--> LSPs mapping at the edge LSR • Optional setting of CLP (based on DHCP) Parallel TBR LSPs

  29. Multi-VC TBR modeData Path ATM LSR Parallel TBR LSPs • Edge LSR: • per CoS WFQ + per CoS WRED • ATM-LSR • per CoS WFQ + per CoS WEPD • NO per-LVC management!!! • Scalability and better muxing

  30. Multi-VC TBR modeExample Per COS WFQ • Queuing on all links is per-class WFQ (not per LSP) • Resource allocation • Assign weight to each class on per-link basis (e.g. Premium gets 80% of link, Standard gets 20%) • Choice of weights based on expected load & desired performance PER CLASS • No per-router-pair configuration (config independent of topology & geography)

  31. ABR LSP ATM LSR Single `VC’ ABR mode • 1 single LVC per FEC • ABR control algorithms are enabled on LSPs • Extention of “IPATMCoS” feature • ATM-LSRs push congestion towards edge LSRs • Edge-LSRs: WRED/WFQ per-LSP queues

  32. Single VC ABR mode • ATM-LSR Scheduling = per-VC ABR • ABR parameters: • MCR is effectively zero (to avoid loss/blocking) • “Relative bandwidth” parameter carried by TDP and used by ABR algorithm

  33. Single VC ABRExample KleinStadt B Paris London A Per VC ABR Tarifa • Equal sharing of link A-B is not always desirable: • Configure relative bandwidth on router-pair basis,e.g. Tarifa-KleinStadt = 1; London-Paris = 100 • Resource Allocation : • Sharing of Bandwidth across Edge Pairs via “Relative BW” on a per LSP basis • Sharing of Bandwidth across COS performed through WRED/CBWFQ on Edge

  34. Single-ABR vs Multi-TBR • Multi-VC TBR Mode: • Congestion managed directly at every hop (IP and ATM hops) • Possible Discard at every hop • Resource Allocation per COS per link; does not have to concern itself with topology and geography • Single-VC ABR: • No Loss in the ATM fabric • Discard/Scheduling possible only on the Edge performed by Routers • Resource Allocation optionally per Pair of Edge Routers.

  35. MPLS over ATMF PVCA special Case ATM Forum ATM ATM Forum PVC • Generic Frame MPLS CoS Case! • A Frame LSR uses ATM-F PVC with chosen ATM QoS • Service Differentiation on Frame LSRs at edge of ATM • Use IPATMCoS features! LDP

  36. MPLS over IPATMCoSper-VC IP QoS • Congestion pushed back at the edge • per-VC ATM-F shaping • CBWFQ/WRED on IP per-VC Queue ATM-F service class enforced

  37. MPLS over IPATMCoSBundle IP QoS • per-VC ATM-F shaping • DSCP to VC mapping • WRED on IP per-VC Q ATM-F service class enforced 1! IGP adajacency

  38. MPLS VPN CoS Presentation_ID 38 © 1999, Cisco Systems, Inc.

  39. MPLS VPN QoS Architecture • 2 very distinct point of views: • How the SP will market the service (SLA) • What are the mechanisms for SP to meet the commitments/SLA • FR analogy: • sell 64 kb/s CIR for 99.5% of the time • reserve 64/overbooking kb/s + admission control + selective discard + …

  40. ECR 512k ICR 512k ECR 128k ECR 128k ICR 256k ICR 256k How to market MPLS VPN CoS?ICR concept - hose model VPN_A site 4 VPN SP VPN_A site 2 VPN_A site 3 Hose Model (point-to-multipoint commodity)Draft-duffield-vpn-qos-framework.txt, AT&T

  41. Proposed SLA for CoS C1 • As long as for each site S of VPN X: • S sends less than ICR • S receives less than ECR (optional: double-ended SLA) • Then: • loss property is 10^(-n1) • RTT is < m1 ms

  42. Extensible to multiple CoS! CoS X: [nx, mx], price Px Gold: [-10, 100ms], $$$ Silver: [-8, 200ms], $$ BE: [be, be], $

  43. How it should not be marketed • Should not be marketed as Frame Relay QoS: • N1 kb/s guaranteed from Site 1 to Site 2 • N2 kb/s guaranteed from Site 1 to Site 3 • N3 kb/s guaranteed from Site 2 to Site 3 • … • Layer 2 based VPNs (ie FR or ATM) address that need

  44. Advantage of this SLA model • Any to any connectivity • Without requiring the customer to have a precise and complete knowledge of its traffic matrix • Matrix of ICR/ECR allows the provider to better engineer his network (hence, to lower the cost of the commodity) • Per-usage billing is still possible (ICR/ECR then only serve as boundaries)

  45. How to meet SLA • Enforcement of ICR: • CAR: policing in/out of profile • Enforcement of ECR • CAR/TS • MPLS CoS in the SP’s backbone • single-ABR, multi-TBR mode • DiffServ engineering

  46. DiffServ Engineering • Scalability: no per-VPN QoS in BB!!! • This is a pure diffserv design! • Per-Class Scheduling/Discarding at every hop • Resource Allocation based on ICR/ECR sold • share each trunk between different Classes • start conservative • then monitor traffic per class and fine tune • Optimise with per-class Traffic Engineering • Cisco Service Management tool for Tag VPN QoS provisioning

  47. DiffServ EngineeringCapacity Management Presentation_ID 47 © 1999, Cisco Systems, Inc.

  48. DiffServ ArchitectureThe Service Offer 1. The routing topology 2. The speed of the links 3. The link sharing ratios (CBWFQ %) THE Service Offer

  49. DiffServ ArchitectureThe Service Demand 1. The matrix of ICR 2. The matrix of ECR THE Service Demand

  50. DiffServ ArchitectureThere is no magic • Service Offer (per class) >= Service Demand (per class) • How to achieve this? • ‘provisioned QoS’

More Related