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MPLS 신호기술: CR-LDP & RSVP Extensions

MPLS 신호기술: CR-LDP & RSVP Extensions. ETRI/PEC 고석주 sjkoh@pec.etri.re.kr. 서론. MPLS/LDP(Label Distribution Protocol) Traffic Engineering Requirements QoS Routing & Provisioning Use ‘Explicit Routes’ (ER) for LSP setup Two Solutions CR-LDP: Extensions to LDP

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MPLS 신호기술: CR-LDP & RSVP Extensions

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  1. MPLS 신호기술:CR-LDP & RSVP Extensions ETRI/PEC 고석주 sjkoh@pec.etri.re.kr

  2. 서론 • MPLS/LDP(Label Distribution Protocol) • Traffic Engineering Requirements • QoS Routing & Provisioning • Use ‘Explicit Routes’ (ER) for LSP setup • Two Solutions • CR-LDP: Extensions to LDP • RSVP Extensions: Extensions to RSVP 제 2 회 인터넷 워크샵

  3. Constraint-based Routing • Mechanism for LSP setup • To support Traffic Engineering Requirements • Based on Explicit Route (ER) • ER is a constraint • Various Constraints …. • Strict and Loose Explicit Routes • Traffic Characteristics of a path • Preemption • Route Pinning • Resource Class, …. 제 2 회 인터넷 워크샵

  4. CR-LDP (2) • CR-LDP is an extensions to LDP • LDP: for Best-Effort Services • Routing Protocol Information Only • CR-LDP: for QoS Services (Diffserv) • Routing Protocol + Constraints • CR-LSP is setup by Ingress LSR • How to find the Explicit Routes ? • By network provider • Based on various constraints • Currently, Unidirectional point-to-point CR-LSP 제 2 회 인터넷 워크샵

  5. CR-LSP • Constraint-based Routed LSP • is a path like any other LSP • But, CR-LSP is • Based on Explicit Routes • Based on Routing Table plus Constraints • initiated by Ingress LSR • for traffic load balancing & QoS routing 제 2 회 인터넷 워크샵

  6. Strict & Loose Routes • Explicit Route (ER) • ER consists of a list of ER-hops (or nodes) • ER is represented in a “Label Request” message • Strict ER-hop: one node • Loose ER-hop: a group of nodes • Subset of the nodes may be traversed by CR-LSP • This increases local flexibility for LSP setup • Allow imperfect information on a detailed path • Abstract Node : including strict & loose node • Thus, CR-LSP is a list of abstract nodes 제 2 회 인터넷 워크샵

  7. CR-LSP with Explicit Route Strict ER-Hop: 1, 3, 4 Loose ER-Hop: 2 Prefix 24 Prefix 32 Prefix 32 Prefix 32 Hop 1 Hop 4 Hop 3 Hop 2 Conventional IP Routing is applied 제 2 회 인터넷 워크샵

  8. Other Constraints • Traffic Characteristic of a Path • Constraints on Bandwidth: peak rate, committed rate • Preemption • If a route with sufficient resource can not be found • Then existing path is preempted by the new path • Setup & Holding Priority for a path • Route Pinning (in a loose ER-hop) • Resource Classes (Colors) • Which resource class (link) can be used by CR-LSP ? 제 2 회 인터넷 워크샵

  9. CR-LDP vs. LDP • CR-LDP = Basic LDP + Extensions • Discovery/Label Request/Label Mapping/ Notification/Withdraw & Release Messages • Additional TLVs (Type-Length-Value) • ER-TLV/ER-Hop TLV • Traffic Parameters TLV • Preemption TLV • LSPID TLVs • Resource Class (Color) TLV 제 2 회 인터넷 워크샵

  10. Label Request Message • Format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Label Request (0x0401) | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FEC TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Return Message ID TLV (mandatory) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSPID TLV (CR-LDP, mandatory) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Pinning TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Resource Class TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Pre-emption TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  11. Label Mapping Message • Format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Label Mapping (0x0400) | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FEC TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Request Message ID TLV (mandatory) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSPID TLV (CR-LDP, mandatory) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic TLV (CR-LDP, optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  12. Explicit Route TLV • ER-TLV specifies the path to be taken by CR-LSP • ER-TLV is composed of one or more ER-Hop TLV 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| ER-TLV (0x0800) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ............ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  13. ER-Hop TLV • L bit: strict (0) or loose (1) ER-Hop • Four ER-Hop types are currently defined 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| ER-Hop-Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Content // | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value Type In Loose ER-Hop ----- --------------------- --------------- 0x801 IPv4 prefix prefix < 32 bit 0x802 IPv6 prefix prefix < 128 bit 0x803 Autonomous system number AS domain 0x804 LSPID tunnel ingress pt. (new CR-LSP, stacking) 제 2 회 인터넷 워크샵

  14. Traffic Parameters (1) • TLV Format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| Traf. Param. TLV (0x0810)| Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Frequency | Reserved | Weight | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Data Rate (PDR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Burst Size (PBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Data Rate (CDR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Burst Size (CBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Excess Burst Size (EBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  15. Traffic Parameters (2) • Flags (1 octet) • Each traffic parameter is Negotiable or not • Frequency (1 octet) • How often should ‘CDR’ be available for CR-LSP ? • Very Frequent, Frequent, Unspecified • Weight (1 octet) • Relative share of possible excess bandwidth • Weight of CR-LSP in terms of Resources • MPLS-domain specific 제 2 회 인터넷 워크샵

  16. Traffic Parameters (3) • Parameters • Peak Data Rate (PDR): peak rate • Peak Burst Size (PBS) • Committed Data Rate (CDR): mean rate • Committed Burst Size (CBS) • Excess Burst Size (EBS): the extent to exceed CDR • Peak Rate Token Bucket • PDR with PBS • Committed Rate Token Bucket • CDR with CBS and EBS 제 2 회 인터넷 워크샵

  17. Preemption TLV • Setup & holding Priority • 0 (most important path) • 7 (least important path) • Competition between ... • HoldPrio of “Old” LSP and SetPrio of “New” LSP 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| Preemption-TLV (0x0820) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SetPrio | HoldPrio | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  18. LSP-ID TLV • Unique identifier of a CR-LSP • LSP-ID is composed of • Ingress LSR ID • Locally unique CR-LSP ID within the Ingress LSR 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| LSPID-TLV (0x0821) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Local CRLSP ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress LSR Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  19. Resource Class TLV • Resource Class defined in [TER] • Currently, 32 resource classes are defined • Which links (of 32) are acceptable by this CR-LSP ? • allows the network topology to be pruned • In particular, for “Loose ER-hop” 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| ResCls-TLV (0x0822) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RsCls | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  20. Route Pinning TLV • P bit • 1 : Route-pinning is requested • 0 : Route-pinning is not requested • When it is not desirable to change the path 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| 0x823 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 제 2 회 인터넷 워크샵

  21. RSVP Extensions • Overview • Use of RSVP to establish ‘LSP tunnel’ • Functionality is almost the sane as CR-LDP • Requirements for Traffic Engineering • RSVP piggybacks Label Information • Additional RSVP Objects for Explicit Routing • Motivations • RSVP is a popular and mature technology • RSVP Flow: MPLS FEC • RSVP Signaling: Downstream on Demand 제 2 회 인터넷 워크샵

  22. Five New Objects • New objects are added to RSVP Path & Resv message • Similar functionality to CR-LDP, for example, • Label Request Object (in RSVP Path Message) • Label Request Message (in CR-LDP) Object name Applicable RSVP messages --------------- ------------------------ LABEL_REQUEST Path LABEL Resv EXPLICIT_ROUTE Path RECORD_ROUTE Path, Resv SESSION_ATTRIBUTE Path 제 2 회 인터넷 워크샵

  23. LSP Tunnel Operation • RSVP Path Message • Label_Request Object • Explicit_Route Object • Session_Attribute Object • additional control info.: preemption, priority, ... • Record_Route Object • error notification, loop detection, .. • RSVP Resv Message • Label Object • Record_Route Object • Sender receives information on the actual route 제 2 회 인터넷 워크샵

  24. CR-LDP & RSVP (1) • Both can be used with LDP • CR-LDP & RSVP for Explicit Routing • LDP for Best-Effort Traffic • One Goal, but Two Different Methods • CR-LDP is more similar to LDP • CR-LDP + LDP = One Set • RSVP implements LDP or CR-LDP in another way • RSVP is additional to LDP 제 2 회 인터넷 워크샵

  25. CR-LDP & RSVP (2) • Target Services • CR-LDP for Differentiated Service • RSVP extensions for Integrated Services • Scalability • CR-LDP (Diffserv) is more scalable ? • RSVP (Intserv) is less scalable ? • Similarity to ATM • CR-LDP is closer to ATM • Definition of Traffic Parameters 제 2 회 인터넷 워크샵

  26. CR-LDP & RSVP (3) • Inter-operability with ATM • CR-LDP: Ship-in-the-Night Mode • Resource Reservation • CR-LDP: Sender-Initiated • RSVP extensions: Receiver-Initiated • In the Market ? • RSVP is being steadily deployed: Cisco System • CR-LDP is relatively new in the Market: Nortel, etc.. • Who win ? 제 2 회 인터넷 워크샵

  27. 결론 • MPLS/LDP • A solution for combination of IP and ATM • Ship-in-the-Night Mode: IP over ATM (?) • Many Problems still remain • Multicast, QoS, Interoperation with non-MPLS • and the other implementation-specific problems • CR-LDP/RSVP • A solution for QoS provisioning using explicit route • Which is more efficient ? • Which will win in the market ? 제 2 회 인터넷 워크샵

  28. 참고문헌 • LDP • “Label Distribution Protocol Specification” • draft-ietf-mpls-ldp-05.txt • CR-LDP • “Constraint-Based LSP Setup using LDP” • draft-ietf-mpls-cr-ldp-01.txt • RSVP Extensions • “Extensions to RSVP for LSP Tunnels” • draft-ietf-mpls-rsvp-lsp-tunnel-02.txt 제 2 회 인터넷 워크샵

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