Network Working Group Internet Draft T. Nadeau Cisco Systems, Inc. Category: Informational Y(J) Stein Rad Data Communications March 2006 Pseudowire Performance and Timing Measurement draft-nadeau-pwe3-perf-timing-measure-00.txt Status of This Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (2006). Abstract To-date, no intrinsic mechanisms exist for pseudowires that allow operators to measure the performance of a pseudowire. Only the existing Virtual Circuit Connectivity Verification protocol allows for the verification of connectivity of a pseudowire. This document defines the problems that must be solved in this space, and provides discussion points around the issues of Nadeau & Stein Expires August 2006 [Page 1] draft-nadeau-pwe3-perf-time-measure-00 March 1, 2006 pseudowire performance measurement, including timing synchronization and packet loss detection. Table of Contents 1. Introduction ....................................................3 3. Terminology .....................................................3 4. Discussion Points .. ............................................4 5. Security Considerations ........................................76 6. Contributors ...................................................77 7. Acknowledgements ...............................................77 8. IANA Considerations ............................................77 9. References .....................................................77 9.1. Normative References ......................................77 9.2. Informative References ....................................78 10. Authors' Addresses ............................................79 1. Introduction Current work is under way in the IETF's PWE3 working group to specify a suite of protocols to be used to transport various types of layer-2 data across public service transport networks such as MPLS and IP (L2TPv3). This document defines the problems that must be solved in this space, and provides discussion points around the issues of pseudowire performance measurement, including timing synchronization and packet loss detection. Some pseudowires carry data that requires strict timing to prevent jitter. For example, Time Division Multiplexing pseudowires that carry mobile phone transmissions have stringent timing parameters. Also, some deployments also require that packet loss detection be also possible. This document provides discussion points around the issues of pseudowire timing and packet loss, as well as potential extensions to the existing pseudowire control channel for detection and possible correction of timing issues. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Terminology Nadeau & Stein Expires August 2006 [Page 2] draft-nadeau-pwe3-perf-time-measure-00 March 1, 2006 This document uses terminology from the pseudowire architecutre specification [RFC3985]. 4. Discussion Points 4.1 Current Limitations VCCV presently provides only connectivity verification full PW OAM should also provide measurements of one way and round trip delay. Currently no mechanisms exist natively in PWE3 protocols to accomplish the following: PDV (+ distribution? spectrum?) Packet loss ratio or actual packet loss Delay measurement Jitter measurement With regard to the above, detecting PL is straight forward if the PW is TDM, but for other PW types, you may need an OAM stream that has high enough rate to give you the statistics you need, and is guaranteed to follow the same path as the user data. This implies the use of VCCV to carry this control information. For PWs it is also useful to monitor performance characterists in order to trigger backup PWs for fast switch-over. Maintain clock synchronization for multiple PWs. Issue with clock synchronization information in control channel is that in some implementations this is handled via the "slow" forwarding path. In particular the problem with cellular applications is that they want very tight timing, which can not always be guaranteed over PSNs. Are there are better ways of doing this than using the PW control channel? Tim Frost proposed NTP over PW in one of the NTP WG meetings and Ron Cohen proposed extending 1588 to MPLS recently. We should compare 1588 to adaptive methods. The current thinking is that 1588 doesn't really help unless there are "boundary clocks" - which require HW upgrades to switches. Nadeau & Stein Expires August 2006 [Page 3] draft-nadeau-pwe3-perf-time-measure-00 March 1, 2006 Do we really need to providing NTP-level wall-clocks for PWs? Do we need to provide a PRC-like frequency standard? Do we need to provide timing for 2G cellular sites or 3G cellular sites? 4.2 CW format use PWACH What should the time format be? - RTP style 32 bit based on N*8KHz - NTP style seconds expressed as 32 bit integer + 32 bit fraction - ICMP style 32 bit milliseconds - IEEE 1588 style 32 bit seconds + 32 bit nanoseconds How many timestamps should packet format support? 1. for approximate round-trip 2. for approximate one-way 3. for round-trip with D t 4. for ICMP-like timestamps N. More than 4 for IEEE 1588-like timestamps 4.3 How do we handle loop-back requests? 4.4 Current Proposals to Move Forward Define new control channel types for performance measurement and timing. 10. Security Considerations TBD. 11. Contributors Thomas D. Nadeau Cisco Systems, Inc. 300 Beaver Brook Road Boxboro, MA 01719 Phone: +1-978-936-1470 EMail: tnadeau@cisco.com Nadeau & Stein Expires August 2006 [Page 4] draft-nadeau-pwe3-perf-time-measure-00 March 1, 2006 Yaakov (Jonathan) Stein RAD Data Communications 24 Raoul Wallenberg St., Bldg C Tel Aviv 69719 ISRAEL Phone: +972 3 645-5389 Email: yaakov_s@rad.com 12. Acknowledgements TBD. 13. IANA Considerations TBD. 14. References 14.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC3985] [VCCV] Nadeau, T. D., Aggarwal, R., "Pseudo Wire Virtual Circuit Connectivity Verification (VCCV)", draft-ietf-pwe3-vccv-08.txt, March 2006 14.2. Informative References 15. Authors' Addresses Thomas D. Nadeau Cisco Systems, Inc. 1414 Massachusetts Ave. Boxborough, MA 01719 EMail: tnadeau@cisco.com Full Copyright Statement Nadeau & Stein Expires August 2006 [Page 5] draft-nadeau-pwe3-perf-time-measure-00 March 1, 2006 Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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