Precision Time Protocol Precision Time Protocol over MPLSover MPLS

draft-ronc-ptp-mpls-00.txt

PWE3 WG IETF Chicago 2007

Ron Cohen

ronc@resolutenetworks.com

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AgendaAgenda

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

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PTP in a nutshell

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Protocol OperationProtocol Operation

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Protocol Operation (Cont.)Protocol Operation (Cont.)

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Main PTP EntitiesMain PTP Entities

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Sync and Delay-Req formatsSync and Delay-Req formats

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EncapsulationsEncapsulations

• 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”

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PTP over MPLS Encapsulation

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PTP MPLS EncapsulationPTP MPLS Encapsulation

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PTP MPLS EncapsulationPTP 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

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Tunnel and PTP LSPs

Scope limited to Point to Point LSP

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Tunnel and PTP LSPsTunnel 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

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Tunnel and PTP LSPs (Cont.)Tunnel and PTP LSPs (Cont.)

• Peer to Peer PTP LSPs connects between PTP peers for Pdelay Measurements only

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Similarity to Multi-Segment PWSimilarity 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

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PTP EntitiesPTP Entities

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PTP Entities over MPLSPTP 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

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MPLS Communication Path ExampleMPLS Communication Path Example

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PTP LSP Setup and Signaling

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PTP LSP SetupPTP 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

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PTP FECPTP FEC

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Open issues and Next Steps

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Open IssuesOpen 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

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Summary and ProposalSummary 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

Thank YouThank You

Ron Cohen

ronc@resoluteNetworks.com

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Multi-Segment PTP ScenarioMulti-Segment PTP Scenario