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

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 Align Master to Slave Time/Frequency Sync and Follow-Up messages downstream Measure Master to Slave Delay Delay-Request and Delay-Response exchange End to End (E2E) measurement Measure per-link Delay (Optional) Pdelay-Request, Pdelay-Response and Pdelay- Response-Follow-Up Peer to Peer (P2P) measurement

5 Protocol Operation (Cont.) Master-Slave Hierarchy Setup and Maintenance Announce messages sent from master to slaves Used to relay synchronization status and build hierarchy Signaling Signaling messages exchanged between clock for negotiation, setup etc. Clock Management Management messages sent between manager and clocks

6 Main PTP Entities Ordinary clock Grand Master is the source of time/frequency Ordinary slave clocks are the synchronization clients Boundary Clock Connects between different networks or administrative domains Does not forward PTP messages Slave on one port and Master/Passive on others Transparent Clock Forwards PTP messages Measures and Corrects PTP messages to compensate for queuing processing and propagation delays

7 Sync and Delay-Req formats

8 Encapsulations PTP defined over:  Ethernet  UDP/IPv4  UDP/IPv6  DeviceNet, ControlNet, IEC 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 Each clock has a globally unique clock identity Based either on EUI-64 / MAC address / Private ID networks Identity A logical access point of a PTP clock for PTP communications to the communications network. Port A segment of a network enabling direct communication between two PTP ordinary or boundary clocks. Communication Path A logical grouping of PTP clocks that synchronize to each other using the PTP protocol, but that are not necessarily synchronized to PTP clocks in another PTP domain. Domain

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

Thank You Ron Cohen

26 Multi-Segment PTP Scenario