I E T F 6 3, 3 rd. A U G U S T draft-frost-pwe3-timing-pw-reqs-00 IETF 63 PWE3 Working Group Paris, August 2005

I E T F 6 3, 3 rd. A U G U S T [Page 1] Why do we need this draft?  Purpose: To define the requirements of a protocol suitable for conveying Timing and Synchronization over Pseudo-Wires  Haven’t we done this already (e.g. TDM PWs with timing)? –there are applications for more general timing distribution, outside the TDM context –some applications require absolute time alignment, not just phase and frequency –separating the transport of timing and data allows improvement in the quality of the recovered clock  Aren’t there existing solutions (e.g. NTP, IEEE1588)? –these describe how to carry timing across a LAN or the internet –they don’t explain how to distribute timing over PW services –they may be candidates for a protocol to be re-used over a timing PW

I E T F 6 3, 3 rd. A U G U S T [Page 2] Potential Applications  There are many applications that require distribution of accurate synchronization and timing: –Industrial applications –Real-time services –Packet voice and video –Telecom applications –Synchronization of IP PBXs or Voice Gateways –Synchronization of cellular base-stations –TDM emulation –Improvement in timing quality over what can be achieved with existing TDM PWs

I E T F 6 3, 3 rd. A U G U S T [Page 3] Possible Timing PW scenario Secondary Time Server ~ PRS ~ Carrier Packet Network PE tunnel Primary Time Server timing pseudo-wires CE timing attachment circuits

I E T F 6 3, 3 rd. A U G U S T [Page 4] Main Requirements  Performance –Requirements are application-specific, and are defined in the normative references for the applications –For example, G.pactiming is in the process of specifying the timing performance requirements for wired TDM emulation  Connectivity and compatibility  Robustness –Should be robust in the presence of common PSN error conditions  Redundancy –Should be able to monitor and switch over to alternative timing sources –Needs an indication of the quality of timing sources  Security –Authentication of timing sources

I E T F 6 3, 3 rd. A U G U S T [Page 5] Comparison of draft-ietf-ntp-reqs-00 and draft-frost-timing-pw-reqs-00 NTPv4 RequirementsTiming PW Reqs. Performance Yes, TBD, (ms range) By reference to ext. stds. (  s range) Configuration & setupYes By reference to PWE3 architecture Security and Authentication Yes, defined mechanism Yes, method not defined Robustness Yes, covers bad implementations Yes, covers PSN errors RedundancyYes Operational requirements Yes, reference to NTP hierarchy Yes, sync. quality messages

I E T F 6 3, 3 rd. A U G U S T SIMPLY COMMUNICATING c e s o p. z a r l i n k. c o m w w w. z a r l i n k. c o m