CCAMP Working Group                                        Rakesh Gandhi
Internet-Draft                                                 Zafar Ali
Intended status: BCP                           Gabriele Maria Galimberti
Expires: January 16, 2014                            Cisco Systems, Inc.
                                                           July 15, 2013



         RSVP-TE Extensions For Signaling GMPLS Restoration LSP
              draft-gandhi-ccamp-gmpls-restoration-lsp-01


Abstract

   In transport networks, there are requirements where Generalized
   Multi-Protocol Label Switching (GMPLS) recovery scheme need to employ
   restoration LSP while keeping resources for the working and/ or
   protecting LSPs reserved in the network. Existing GMPLS recovery
   procedures do not address these requirements. This document describes
   best common practice for using RSVP-TE for GMPLS recovery with
   restoration LSP.


Status of this Memo

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   This Internet-Draft will expire on May 31, 2013.

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  4
   3.  Restoration LSP Signaling Extensions . . . . . . . . . . . . .  5
     3.1.  Signaling Procedure  . . . . . . . . . . . . . . . . . . .  5
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   6.  Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . .  5
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     7.1.  Normative references . . . . . . . . . . . . . . . . . . .  6
     7.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7


















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1.  Introduction

   Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS to
   include support for different switching technologies [RFC3471]
   [RFC3473]. These switching technologies provide several protection
   schemes [RFC4426][RFC4427] (e.g. 1+1, 1:N and M:N). GMPLS RSVP-TE
   signaling has been extended to support various recovery schemes to
   establish Label Switched Paths (LSPs) [RFC4872][RFC4873], typically
   working LSP and protecting LSP. [RFC4427] Section 7 specifies various
   schemes for GMPLS restoration.

   In GMPLS recovery schemes currently considered, restoration LSP is
   signaled after the failure has been detected and notified on the
   working LSP. These schemes assume that working LSP is removed from
   the network before restoration LSP is signaled. In transport
   networks, as working LSPs are typically signaled over a nominal path,
   there are many scenarios where service providers would like to keep
   resources associated with the working LSPs reserved. This is to make
   sure that the service (working LSP) can use the nominal path when the
   failure is repaired. Consequently, in transport networks one can
   employ a recovery scheme where a new restoration LSP is signaled
   while working LSP and/ or protecting LSP are not torn down in control
   plane due to a failure. Restoration LSP differs from a secondary LSP
   in the way that secondary LSP does not reserve resources in the data
   plane and is not able to carry any traffic until it is refreshed
   whereas restoration LSP does reserve resources and is able to carry
   traffic.

   One example of the recovery scheme considered in this draft is 1+R
   recovery. The 1+R recovery is exemplified in Figure 1. In this
   example, working LSP on path A-B-C-Z is pre-established. Typically
   after a failure detection and notification on the working LSP, a
   second LSP on path A-H-I-J-Z is established as a restoration LSP.
   Unlike protection LSP, restoration LSP is signaled on as needed
   basis.


                        A --- B --- C --- Z
                         \               /
                           H --- I --- J


           Figure 1: An example of 1+R recovery scheme


   During failure with 1+R recovery scheme, in general, working LSP
   resources are not released and working and restoration LSPs coexist
   in the network. Nonetheless, working and restoration LSPs can share



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   network resources. Typically when failure is recovered on the working
   LSP, restoration LSP is no longer required and torn down (e.g.
   revertive mode).

   Another example of the recovery scheme considered in this draft is
   1+1+R. In 1+1+R, a restoration LSP is signaled for the working LSP
   and/ or the protecting LSP after the failure has been detected and
   notified on the working LSP or the protecting LSP. The 1+1+R recovery
   is exemplified in Figure 2. In this example, working LSP on path A-B-
   C-Z and protecting LSP on path A-D-E-F-Z are pre-established. After a
   failure detection and notification on a working LSP or protecting
   LSP, a third LSP on path A-H-I-J-Z is established as a restoration
   LSP. The restoration LSP in this case provides protection against a
   second order failure. Restoration LSP is torn down when the failure
   on the working or protecting LSP is repaired.



                           D --- E --- F
                         /               \
                        A --- B --- C --- Z
                         \               /
                           H --- I --- J


           Figure 2: An example of 1+1+R recovery scheme


   [RFC4872] Section 14 defines PROTECTION object for GMPLS recovery
   signaling. The PROTECTION object is used to identify primary and
   secondary LSPs using S bit and protecting and working LSPs using P
   bit. However, the PROTECTION object does not have a way to identify
   restoration LSP. [RFC4872] and [RFC6689] define the usage of
   ASSOCIATION object for further associating GMPLS working and
   protecting LSPs for the case where restoration LSP is signaled for
   GMPLS recovery after the working or protecting LSPs are removed.

   This draft outlines the best common practice for identifying the
   restoration LSP for GMPLS recovery where working and protecting LSP
   resources are kept reserved.


2.  Conventions used in this document

   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 [RFC2119].




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3.  Restoration LSP Signaling Extensions

3.1.  Signaling Procedure

  Where GMPLS recovery scheme need to employ restoration LSP while
  keeping resources for the working and/ or protecting LSPs reserved in
  the network, restoration LSP is signaled with ASSOCIATION object with
  the association ID set to the LSP ID of the LSP it is restoring. For
  example, when a restoration LSP is signaled for a working LSP, the
  ASSOCIATION object in the restoration LSP contains the association ID
  set to the LSP ID of the working LSP. Similarly, when a restoration
  LSP is signaled for a protecting LSP, the ASSOCIATION object in the
  restoration LSP contains the association ID set to the LSP ID of the
  protecting LSP.

  The procedure for signaling the PROTECTION object is specified in
  [RFC4872][RFC4873] and does not change. Restoration LSP for the
  working LSP is signaled with P bit cleared and restoration LSP for the
  protecting LSP is signaled with P bit set.

  When using a GMPLS recovery mode, where working LSP is destroyed, and
  the restoration LSP is promoted to be the new working LSP, restoration
  LSP RSVP Path message MUST be refreshed by using the
  ASSOCIATION_OBJECT.LSP_ID from the destroyed working LSP
  ASSOCIATION_OBJECT.LSP_ID.

  When using a GMPLS recovery mode, where a protecting LSP is destroyed,
  and the restoration LSP is promoted to be the new protecting LSP,
  restoration LSP RSVP Path message MUST be refreshed by using the
  ASSOCIATIN_OBJECT.LSP_ID from the destroyed protecting LSP
  ASSOCIATION_OBJECT.LSP_ID.


4.  IANA Considerations

  This document makes no request for IANA action.


5.  Security Considerations

  This document introduces no additional security considerations. For a
  general discussion on MPLS and GMPLS related security issues, see the
  MPLS/GMPLS security framework [RFC5920]. In addition, the
  considerations specified in [RFC4872] and [RFC4873] will apply.


6.  Acknowledgement




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  The authors would like to thank George Swallow for the discussion on
  the GMPLS restoration.


7.  References

7.1.  Normative references

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

   [RFC2205]  Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, September 1997.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC3471]  Berger, L., Editor, "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Functional Description", RFC
              3471, January 2003.

   [RFC3473]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC4872]  Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE
              Extensions in Support of End-to-End Generalized Multi-
              Protocol Label Switching (GMPLS) Recovery", RFC 4872, May
              2007.

   [RFC4873]  Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
              "GMPLS Segment Recovery", RFC 4873, May 2007.

   [RFC6689]  Berger, L, "Usage of the RSVP ASSOCIATION Object", RFC
              6689, July 2012.














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7.2.  Informative References

   [RFC4426]  Lang, J., Rajagopalan B., and D.Papadimitriou, Editors,
              "Generalized Multiprotocol Label Switching (GMPLS)
              Recovery Functional Specification", RFC 4426, March 2006.

   [RFC4427]  Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
              (Protection and Restoration) Terminology for Generalized
              Multi-Protocol Label Switching, RFC 4427, March 2006.

   [RFC5920]  Fang, L., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, July 2010.



Authors' Addresses


   Rakesh Gandhi
   Cisco Systems, Inc.

   Email: rgandhi@cisco.com


   Zafar Ali
   Cisco Systems, Inc.

   Email: zali@cisco.com


   Gabriele Maria Galimberti
   Cisco Systems, Inc.

   Email: ggalimbe@cisco.com

















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