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Versions: 00 01 02 03 04 05 06 07 draft-ietf-mpls-residence-time

MPLS Working Group                                             G. Mirsky
Internet-Draft                                                  Ericsson
Intended status: Standards Track                                J. Drake
Expires: April 24, 2014                                      K. Holleman
                                                        Juniper Networks
                                                               S. Bryant
                                                           Cisco Systems
                                                           A. Vainshtein
                                                             ECI Telecom
                                                        October 21, 2013


               Residence Time Measurment in MPLS network
                  draft-mirsky-mpls-residence-time-00

Abstract

   This document specifies G-ACh based Residence Time Measurement and
   how it can be used by time synchronization protocols being
   transported over MPLS domain.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Conventions used in this document . . . . . . . . . . . . . 3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . 3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . . . 3
   2.  Residence Time Measurement  . . . . . . . . . . . . . . . . . . 4
   3.  G-ACh for Residence Time Measurement  . . . . . . . . . . . . . 4
   4.  Theory of Operation . . . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6





























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1.  Introduction

   Time synchronization protocols, Network Time Protocol version 4
   (NTPv4) [RFC5905] and Precision Time Protocol (PTP) Version 2, a.k.a.
   IEEE-1588 v.2, can be used to syncronized clocks across network
   domain.  In some scenarios calculation of time packet of time
   syncronization protocol spends within a node, called Resident Time,
   can improve accuracy of clock syncronization.  This document defines
   new Generalized Associated Channel (G-ACh) that can be used in Multi-
   Protocol Label Switching (MPLS) network to measure Residence Time
   over Label Switched Path (LSP) or Pseudo-wire (PW).  Transport of
   packets of a time synchronization protocol over MPLS domain is
   outside of scope of this document.

1.1.  Conventions used in this document

1.1.1.  Terminology

   MPLS: Multi-Protocol Label Switching

   ACH: Associated Channel

   TTL: Time-to-Live

   G-ACh: Generic Associated Channel

   GAL: Generic Associated Channel Label

   NTP: Network Time Protocol

   PTP: Precision Time Protocol

   PW: Pseudo-wire

   LSP: Label Switched Path

   OAM: Operations, Administration, and Maintenance

1.1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].







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2.  Residence Time Measurement

   Packet Loss and Delay Measurement for MPLS Networks [RFC6374] can be
   used to measure one-way or two-way end-to-end propagation delay over
   LSP or PW.  But none of these metrics is useful for time
   syncronization across a network.  For example, PTPv2 uses "residence
   time", time it takes for a PTPv2 packet to transit a node, not delay
   of propagation over a link connected to a port receiving the PTP
   event message.


3.  G-ACh for Residence Time Measurement

   RFC 5586 [RFC5586] and RFC 6423 [RFC6423] extended applicability of
   PW Associated Channel (ACH) [RFC5085] to LSPs.  G-ACh presents
   mechanism to transport OAM and other control messages and trigger
   their processing by arbitrary transient LSRs through controlled use
   of Time-to-Live (TTL) value.

   Packet format for Residence Time Measurement presented in Figure 1

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|   Reserved    |          RTM Channel          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |                     Scratch Pad                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Payload                                   |
    |                                                               |
    .                                                               .

       Figure 1: G-ACh packet format for Residence Time Measurement

   Version field is set to 0, as defined in RFC 4385 [RFC4385].
   Reserved field must be set to 0 on trnsmit and ignored at reception.
   Residence Time Measurement (RTM) G-ACh - value to be allocated by
   IANA.  Scratch pad - 8 octets long field that can be used to
   accumulate residence time the packet spends traversing the node.
   Payload - optional field.  May be used to transport a packet of time
   synchronization protocol.


4.  Theory of Operation

   An LSP ingress LSR, based on information collected through IGP
   extensions that are outside of scope of this document, select to use



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   use Residence Time Measurement G-ACh.  The LSR then would use GAL and
   G-ACh header.  The LSR will zero out Scratch Pad field and set TTL
   value so that TTL expiration will be at the next RTM capable
   downstream LSR.

   Upon expiration of RTM packet an LSR would substract local time value
   from the value in the Scratch Pad field and processes the packet
   according to label stack information.  If the packet to be forwarded,
   the LSR will set TTL value so that the TTL expiration takes place at
   the next RTM-capable downstream LSR.  The LSR adds local time value
   to the value in the Scratch Pad field as close to the start of packet
   transmition as possible.

   LSP terminating LSR may use value accumulated in the Scratch Pad
   field as time correction as it represent sum of Residence Time of all
   traveresed RTM capable LSR between end points of the LSP.  For
   example, egress LSR may be PTP Boundary Clock syncronized to a Master
   Clock and as Slave Clock will use accumulated in the Scratch Pad
   Field value to update PTP's Correction Field.


5.  IANA Considerations

   IANA is requested to reserve a new G-ACh as follows:

          +-------+----------------------------+---------------+
          | Value |         Description        | Reference     |
          +-------+----------------------------+---------------+
          | X     | Residence Time Measurement | This document |
          +-------+----------------------------+---------------+

                  Table 1: New Residence Time Measurement


6.  Security Considerations

   Routers that support Residence Time Measurement are subject to the
   same security considerations as defined in [RFC5586] and [RFC6423].


7.  Acknowledgements

   TBD


8.  References





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8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4385]  Bryant, S., Swallow, G., Martini, L., and D. McPherson,
              "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
              Use over an MPLS PSN", RFC 4385, February 2006.

   [RFC5085]  Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit
              Connectivity Verification (VCCV): A Control Channel for
              Pseudowires", RFC 5085, December 2007.

   [RFC5586]  Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
              Associated Channel", RFC 5586, June 2009.

   [RFC5905]  Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
              Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, June 2010.

   [RFC6423]  Li, H., Martini, L., He, J., and F. Huang, "Using the
              Generic Associated Channel Label for Pseudowire in the
              MPLS Transport Profile (MPLS-TP)", RFC 6423,
              November 2011.

8.2.  Informative References

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS Networks", RFC 6374, September 2011.


Authors' Addresses

   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com


   John Drake
   Juniper Networks

   Email: jdrake@juniper.net








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   Keith Holleman
   Juniper Networks

   Email: holleman@juniper.net


   Stewart Bryant
   Cisco Systems

   Email: stbryant@cisco.com


   Alexander Vainshtein
   ECI Telecom

   Email: Alexander.Vainshtein@ecitele.com



































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