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Precision Time Protocol over MPLS

Precision Time Protocol over MPLS. draft-ronc-ptp-mpls-00.txt PWE3 WG IETF Chicago 2007 Ron Cohen ronc@resolutenetworks.com. Agenda. IEEE1588/PTP in a nutshell Encapsulation PTP LSPs LSP Setup and Signaling Open issues Summary and Proposal. PTP in a nutshell. Protocol Operation.

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Precision Time Protocol over MPLS

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  1. Precision Time Protocol over MPLS draft-ronc-ptp-mpls-00.txt PWE3 WG IETF Chicago 2007 Ron Cohen ronc@resolutenetworks.com

  2. Agenda • IEEE1588/PTP in a nutshell • Encapsulation • PTP LSPs • LSP Setup and Signaling • Open issues • Summary and Proposal

  3. PTP in a nutshell

  4. Protocol Operation

  5. Protocol Operation (Cont.)

  6. Main PTP Entities

  7. Sync and Delay-Req formats

  8. Encapsulations • PTP defined over: • Ethernet • UDP/IPv4 • UDP/IPv6 • DeviceNet, ControlNet, IEC 61158 • PTP is used as part of 802.1as "Standard for Local and Metropolitan Area Networks - Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks”

  9. PTP over MPLS Encapsulation

  10. PTP MPLS Encapsulation

  11. PTP MPLS Encapsulation • PTP header immediately follows PW label • Transport Specific Field set to zero for all PTP messages • Compliant with generic PW control word as specified in RFC4385 • A PTP Forwarding Equivalence Class (FEC) is associated with the PW label • Benefits • Bandwidth efficient • Easy to identify PTP Event messages • Easy to process correction field in hardware

  12. Tunnel and PTP LSPs Scope limited to Point to Point LSP

  13. Tunnel and PTP LSPs • Tunnel LSP switches MPLS tunnel labels • Tunnel LSP connects between PTP aware LSRs • E2E PTP LSP switches PTP/PW labels • E2E LSP connects between PTP ordinary and boundary clocks

  14. Tunnel and PTP LSPs (Cont.) • Peer to Peer PTP LSPs connects between PTP peers for Pdelay Measurements only

  15. Similarity to Multi-Segment PW • Transparent clocks behave somewhat similar to PW stitching • Manipulates the correction field of PTP messages In addition to PW label switching • Same administrative domain and PSN on both ends

  16. PTP Entities

  17. PTP Entities over MPLS • Communication Paths • A set of one or more E2E LSPs • Point to Point Communication Path or: • Each ordinary or boundary clock port must form an PTP LSP with all non-slave-only PTP ports. • PTP domains • Different Domains are sent on separate PTP LSPs • PTP ports • PTP port used per E2E PTP LSP or: • Single PTP port used for multiple LSPs

  18. MPLS Communication Path Example

  19. PTP LSP Setup and Signaling

  20. PTP LSP Setup • Use LDP Extensions for setup of PWs (RFC3036) • Extended LDP discovery • Bidirectional LSPs setup • Downstream unsolicited label binding • Use Forwarding Equivalence Class (FEC) to identify the meaning of the label and identify the PW type • New FEC AII and AGI defined • Generalized PWiD (GID) FEC used • End-to-End or Peer-to-Peer PTP PW Types • Port Number and Clock Identity (Port identity) used as Attachment Individual Identifiers (AII) • Domain number used as Attachment Group Identifier

  21. PTP FEC

  22. Open issues and Next Steps

  23. Open Issues • Traffic Engineering • Setup of symmetric LSPs • Use of RSVP-TE for tunnel LSP • Automatic Protection switching • Use of P2MP and MP2MP LSPs • FEC collision • Discovery and Aggregation Friendly AII types • LDP capability negotiation • PTP management messages

  24. Summary and Proposal • PTP direct mapping to MPLS is required • PWE3 is the place to advance this work • Non-IP encapsulation over MPLS • Relevant experts and expertise • Suggest to add to PWE3 agenda • Possibly move to TICTOC if chartered • Coordinate with other WG if required • Suggest to adopt draft-ronc-ptp-mpls-00 as candidate for WG document

  25. Thank You Ron Cohen ronc@resoluteNetworks.com

  26. Multi-Segment PTP Scenario

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