Network Working Group                                    A. D'Alessandro
Internet-Draft                                            Telecom Italia
Intended status: Standards Track                                 J. Ryoo
Expires: August 17, 2013                                            ETRI
                                                       February 13, 2013


   Supporting the Exercise command for PSC linear protection protocol
                      draft-dj-mpls-tp-exer-psc-00

Abstract

   This draft indicates how IETF RFC6378 could be modified to address
   the Exercise function.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on August 17, 2013.

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
   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.





D'Alessandro & Ryoo      Expires August 17, 2013                [Page 1]


Internet-Draft             EXER command in PSC             February 2013


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Updates to the PSC RFC . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Updates to Section 2.1. Acronyms . . . . . . . . . . . . .  4
     2.2.  Updates to Section 3.1. Local Request Logic  . . . . . . .  4
     2.3.  Update to Section 3.2. Remote Requests . . . . . . . . . .  4
     2.4.  Updates to Section 3.6. PSC Control States . . . . . . . .  4
     2.5.  Updates to Section 4.2.2. PSC Request Field  . . . . . . .  5
     2.6.  Updates to Section 4.3.2. Priority of Inputs . . . . . . .  5
     2.7.  Updates to Section 4.3.3. Operation of PSC States  . . . .  5
       2.7.1.  Updates to Section 4.3.3.1. Normal State . . . . . . .  5
       2.7.2.  Updates to Section 4.3.3.6. Do-not-Revert State  . . .  5
       2.7.3.  New subsection for Exercise State  . . . . . . . . . .  5
     2.8.  Updates to Appendix A. PSC State Machine Tables  . . . . .  7
     2.9.  Updates to Appendix B. Exercising the Protection Domain  . 10
   3.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15




























D'Alessandro & Ryoo      Expires August 17, 2013                [Page 2]


Internet-Draft             EXER command in PSC             February 2013


1.  Introduction

   Exercise is a command to test if the PSC communication is operating
   correctly.  More specifically, the Exercise is to test and validate
   the linear protection mechanism and PSC protocol including the
   integrity of the protection path, without triggering the actual
   traffic switching.  It is used while the working path is either
   carrying the traffic or not.  It is lower priority than any "real"
   switch request.  It is only valid in bidirectional switching, since
   this is the only place where one can get a meaningful test by looking
   for a response.

   This command is documented in R84 of [RFC5654] and it has been
   identified as a requirement in the ITU's liaison statement "Liaison
   Statement: Recommendation ITU-T G.8131/Y.1382 revision - Linear
   protection switching for MPLS-TP networks " [LIAISON1] and
   "Recommendation ITU-T G.8131 revision - Linear protection switching
   for MPLS-TP networks [LIAISON2].  This draft is created as an attempt
   to align PSC behaviour and functionalities to meet IETF and ITU-T
   MPLS Transport Profile requirements.































D'Alessandro & Ryoo      Expires August 17, 2013                [Page 3]


Internet-Draft             EXER command in PSC             February 2013


2.  Updates to the PSC RFC

   This section describes the changes required to cover the exercise
   functionality to the PSC protocol defined in [RFC6378]

2.1.  Updates to Section 2.1. Acronyms

   The following text should be added in Section 2.1 in [RFC6378]:

      EXER Exercise
      RR   Reverse Request

2.2.  Updates to Section 3.1. Local Request Logic

   EXER should be included as an operator command.

   The following text should be added:

   o  Exercise (EXER) - Exercise is a command to test if the PSC
      communication is operating correctly.  It is lower priority than
      any "real" switch request.  It is only valid in bidirectional
      switching, since this is the only place where one can get a
      meaningful test by looking for a response.

      The Exercise command shall be issued with the same FPath and Path
      numbers of the NR, RR or DNR request that it replaces.

2.3.  Update to Section 3.2. Remote Requests

   The following text should be added:

   o  Remote EXER - the valid response to EXER message will be an RR
      with the corresponding FPath and Path numbers.  The near end will
      signal a Reverse Request (RR) only in response to an EXER command
      from the far end.

      When Exercise commands are input at both ends, an EXER, instead of
      RR, is transmitted from both ends.

2.4.  Updates to Section 3.6. PSC Control States

   The following text should be added:

   o  Exercise state - The operator has issued the Exercise command to
      test and validate the protection mechanism and PSC protocol
      including the integrity of the protection path, without triggering
      the actual traffic switching.




D'Alessandro & Ryoo      Expires August 17, 2013                [Page 4]


Internet-Draft             EXER command in PSC             February 2013


2.5.  Updates to Section 4.2.2. PSC Request Field

   The following PSC Requests should be added to PSC Request field:

      (3) Exercise - indicates that the transmitting end point is
      exercising the protection channel and mechanism.

      (2) Reverse Request - indicates that the transmitting end point is
      responding to an EXER command from the far end.

2.6.  Updates to Section 4.3.2. Priority of Inputs

   The priority of the Exercise should be inserted between the
   priorities of WTR Expires and No Request.

2.7.  Updates to Section 4.3.3. Operation of PSC States

2.7.1.  Updates to Section 4.3.3.1. Normal State

   Add the following text for Section 4.3.3.1.  Normal State:

   o  A local Exercise input SHALL cause the LER to go into local
      Exercise state and begin transmission of an EXER(0,0) message.

   o  A remote EXER message SHALL cause the LER to go into remote
      Exercise state, and transmit an RR(0,0)message.

2.7.2.  Updates to Section 4.3.3.6. Do-not-Revert State

   Add the following text for Section 4.3.3.6.  Do-not-Revert State:

   o  A local Exercise input SHALL cause the LER to go into local
      Exercise state and begin transmission of an EXER(0,1) message.

   o  A remote EXER message SHALL cause the LER to go into remote
      Exercise state, and transmit an RR(0,1)message.

2.7.3.  New subsection for Exercise State

   Add a new sub-section, Section 4.3.3.7.  Exercise State, with the
   following text:

   In the Exercise state, the user data traffic SHALL remain on the same
   path as the previous state, such as N or DNR.  The local end SHALL
   signal a RR message in response to a remote EXER message.  When both
   ends are in local Exercise state, only the EXER messages are
   exchanged.




D'Alessandro & Ryoo      Expires August 17, 2013                [Page 5]


Internet-Draft             EXER command in PSC             February 2013


   The following describe the reaction to local input:

   o  A local Clear SHALL be ignored if in remote Exercise state.  If in
      local Exercise state, then this input SHALL cause the LER to go
      into Normal state when the LER is configured for revertive mode.
      For non-revertive mode, the LER goes into DNR state.

   o  A local Lockout of protection input SHALL cause the LER to go into
      local Unavailable state and begin transmission of an LO(0,0)
      message.

   o  A local Forced Switch input SHALL cause the LER to go into local
      Protecting administrative state and begin transmission of an
      FS(1,1) message.

   o  A local Signal Fail indication on the protection path SHALL cause
      the LER to go into local Unavailable state and begin transmission
      of an SF(0,0) message.

   o  A local Signal Fail indication on the working path SHALL cause the
      LER to go into local Protecting failure state and begin
      transmission of an SF(1,1) message.

   o  A local Manual Switch input SHALL cause the LER to go into local
      Protecting administrative state and begin transmission of an
      MS(1,1) message.

   o  A local EXER input can be applied when the local end is in remote
      EXER state.  This SHALL cause the LER to remain in the EXER state,
      but begin transmission of an EXER message instead of RR message.

   o  All other local inputs SHALL be ignored.

   When in Exercise state, the following describe the reaction to remote
   messages:

   o  A remote Lockout of protection message SHALL cause the LER to go
      into remote Unavailable state and begin transmission of an NR(0,0)
      message.

   o  A remote Forced Switch message SHALL cause the LER to go into
      remote Protecting administrative state and begin transmission of
      an NR(0,1) message.

   o  A remote Signal Fail message for the protection path SHALL cause
      the LER to go into remote Unavailable state and begin transmission
      of an NR(0,0) message.




D'Alessandro & Ryoo      Expires August 17, 2013                [Page 6]


Internet-Draft             EXER command in PSC             February 2013


   o  A remote Signal Fail message for the working path SHALL cause the
      LER to go into remote Protecting failure state and begin
      transmission of an NR(0,1) message.

   o  A remote Manual Switch message SHALL cause the LER to go into
      remote Protecting administrative state and begin transmission of
      an NR(0,1) message.

   o  A remote DNR message received in remote Exercise state SHALL cause
      the LER to go into DNR state.  A remote DNR message in local
      Exercise state is ignored.

   o  A remote NR message received in remote Exercise state SHALL cause
      the LER to go into Normal state.  A remote NR message in local
      Exercise state is ignored.

   o  All other local inputs SHALL be ignored.

2.8.  Updates to Appendix A. PSC State Machine Tables

   Add the following extended states:

      E::L = Exercise due to local EXER command
      E::R = Exercise due to remote EXER message

   Add the following messages:

      State REQ(FP, P)
      ----- ----------
      E::L  EXER(0,0)for revertive, or EXER(0,1)for non-revertive
      E::R  RR(0,0) for revertive, or RR(0,1) for non-revertive

   Modify the state machine as follows (only relevant cells are shown):

   Part 1: Local input state machine
















D'Alessandro & Ryoo      Expires August 17, 2013                [Page 7]


Internet-Draft             EXER command in PSC             February 2013


   +------+----+------+------+------+------+-----+-------+-------+-----+
   |      | OC | LO   | SF-P | FS   | SF-W | SFc | MS    | WTREx | EXE |
   |      |    |      |      |      |      |     |       | p     | R   |
   +------+----+------+------+------+------+-----+-------+-------+-----+
   | N    |    |      |      |      |      |     |       |       | E:: |
   |      |    |      |      |      |      |     |       |       | L   |
   |      |    |      |      |      |      |     |       |       |     |
   | UA:L |    |      |      |      |      |     |       |       | i   |
   | O:L  |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | UA:P |    |      |      |      |      |     |       |       | i   |
   | :L   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | UA:L |    |      |      |      |      |     |       |       | i   |
   | O:R  |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | UA:P |    |      |      |      |      |     |       |       | i   |
   | :R   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PF:W |    |      |      |      |      |     |       |       | i   |
   | :L   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PF:W |    |      |      |      |      |     |       |       | i   |
   | :R   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PA:F |    |      |      |      |      |     |       |       | i   |
   | :L   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PA:M |    |      |      |      |      |     |       |       | i   |
   | :L   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PA:F |    |      |      |      |      |     |       |       | i   |
   | :R   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | PA:M |    |      |      |      |      |     |       |       | i   |
   | :R   |    |      |      |      |      |     |       |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | WTR  |    |      |      |      |      |     |       |       | i   |
   |      |    |      |      |      |      |     |       |       |     |
   | DNR  |    |      |      |      |      |     |       |       | E:: |
   |      |    |      |      |      |      |     |       |       | L   |
   |      |    |      |      |      |      |     |       |       |     |
   | E::L | [2 | UA:L | UA:P | PA:F | PF:W | i   | PA:M: | i     | i   |
   |      | 0] | O:L  | :L   | :L   | :L   |     | L     |       |     |
   |      |    |      |      |      |      |     |       |       |     |
   | E::R | i  | UA:L | UA:P | PA:F | PF:W | i   | PA:M: | i     | E:: |
   |      |    | O:L  | :L   | :L   | :L   |     | L     |       | L   |
   +------+----+------+------+------+------+-----+-------+-------+-----+



D'Alessandro & Ryoo      Expires August 17, 2013                [Page 8]


Internet-Draft             EXER command in PSC             February 2013


   Part 2: Remote messages state machine

   +------+------+-----+-----+------+------+-----+-----+----+-----+----+
   |      | LO   | SF- | FS  | SF-W | MS   | WTR | DNR | NR | EXE | RR |
   |      |      | P   |     |      |      |     |     |    | R   |    |
   +------+------+-----+-----+------+------+-----+-----+----+-----+----+
   | N    |      |     |     |      |      |     |     |    | E:: | i  |
   |      |      |     |     |      |      |     |     |    | R   |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | UA:L |      |     |     |      |      |     |     |    | i   | i  |
   | O:L  |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | UA:P |      |     |     |      |      |     |     |    | i   | i  |
   | :L   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | UA:L |      |     |     |      |      |     |     |    | i   | i  |
   | O:R  |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | UA:P |      |     |     |      |      |     |     |    | i   | i  |
   | :R   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PF:W |      |     |     |      |      |     |     |    | i   | i  |
   | :L   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PF:W |      |     |     |      |      |     |     |    | i   | i  |
   | :R   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PA:F |      |     |     |      |      |     |     |    | i   | i  |
   | :L   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PA:M |      |     |     |      |      |     |     |    | i   | i  |
   | :L   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PA:F |      |     |     |      |      |     |     |    | i   | i  |
   | :R   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | PA:M |      |     |     |      |      |     |     |    | i   | i  |
   | :R   |      |     |     |      |      |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | WTR  |      |     |     |      |      |     |     |    | i   | i  |
   |      |      |     |     |      |      |     |     |    |     |    |
   | DNR  |      |     |     |      |      |     |     |    | E:: | i  |
   |      |      |     |     |      |      |     |     |    | R   |    |
   |      |      |     |     |      |      |     |     |    |     |    |
   | E::L | UA:L | UA: | PA: | PF:W | PA:M | i   | i   | i  | i   | i  |
   |      | O:R  | P:R | F:R | :R   | :R   |     |     |    |     |    |
   |      |      |     |     |      |      |     |     |    |     |    |




D'Alessandro & Ryoo      Expires August 17, 2013                [Page 9]


Internet-Draft             EXER command in PSC             February 2013


   | E::R | UA:L | UA: | PA: | PF:W | PA:M | i   | DNR | N  | i   | i  |
   |      | O:R  | P:R | F:R | :R   | :R   |     |     |    |     |    |
   +------+------+-----+-----+------+------+-----+-----+----+-----+----+

   [20] Transition to N for revertive mode, transition to DNR for non-
   revervtive mode

2.9.  Updates to Appendix B. Exercising the Protection Domain

   Remove Appendix B.









































D'Alessandro & Ryoo      Expires August 17, 2013               [Page 10]


Internet-Draft             EXER command in PSC             February 2013


3.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.













































D'Alessandro & Ryoo      Expires August 17, 2013               [Page 11]


Internet-Draft             EXER command in PSC             February 2013


4.  Security Considerations

   No specific security issue is raised in addition to those ones
   already documented in [RFC6378]















































D'Alessandro & Ryoo      Expires August 17, 2013               [Page 12]


Internet-Draft             EXER command in PSC             February 2013


5.  Acknowledgements


















































D'Alessandro & Ryoo      Expires August 17, 2013               [Page 13]


Internet-Draft             EXER command in PSC             February 2013


6.  References

6.1.  Normative References

   [RFC5654]  Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
              and S. Ueno, "Requirements of an MPLS Transport Profile",
              RFC 5654, September 2009.

   [RFC6378]  Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
              A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
              Protection", RFC 6378, October 2011.

6.2.  Informative References

   [LIAISON1]  ITU-T SG15, "Liaison Statement: Recommendation ITU-T
              G.8131/Y.1382 revision - Linear protection switching for
              MPLS-TP networks",
              <https://datatracker.ietf.org/liaison/1205/>.

   [LIAISON2]  ITU-T SG15, "Liaison Statement: Recommendation ITU-T
              G.8131 revision - Linear protection switching for
              MPLS-TP networks",
              <https://datatracker.ietf.org/liaison/1234/>.


























D'Alessandro & Ryoo      Expires August 17, 2013               [Page 14]


Internet-Draft             EXER command in PSC             February 2013


Authors' Addresses

   Alessandro D'Alessandro
   Telecom Italia
   via Reiss Romoli, 274
   Torino  10141
   Italy

   Phone: +30 011 2285887
   Email: alessandro.dalessandro@telecomitalia.it


   Jeong-dong Ryoo
   ETRI
   218 Gajeongno
   Yuseong-gu, Daejeon  305-700
   South Korea

   Phone: +82-42-860-5384
   Email: ryoo@etri.re.kr































D'Alessandro & Ryoo      Expires August 17, 2013               [Page 15]