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PCE Working Group                                               C. Barth
Internet-Draft                                                  R. Torvi
Intended status: Standards Track                        Juniper Networks
Expires: January 7, 2016                                       P. Bedard
                                                      Cox Communications
                                                            July 6, 2015


     PCEP Extensions for RSVP-TE Local-Protection with PCE-Stateful
              draft-cbrt-pce-stateful-local-protection-00

Abstract

   Stateful PCE [ietf-pce-stateful-pce] can apply global concurrent
   optimizations to optimize LSP placement.  In a deployment where a PCE
   is used to compute all the paths, it may be beneficial for the local
   protection paths to also be computed by the PCE.  This document
   defines extensions needed for the setup and management of RSVP-TE
   protection paths by the PCE.

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
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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
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   This Internet-Draft will expire on January 7, 2016.

Copyright Notice

   Copyright (c) 2015 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
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   to this document.  Code Components extracted from this document must



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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Local Protection Overview . . . . . . . . . . . . . . . .   3
   4.  Extensions for the LSPA object  . . . . . . . . . . . . . . .   4
     4.1.  The Weight TLV  . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  The Bypass TLV  . . . . . . . . . . . . . . . . . . . . .   4
     4.3.  The LOCALLY-PROTECTED-LSPS TLV  . . . . . . . . . . . . .   5
   5.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  PCEP-Error Object . . . . . . . . . . . . . . . . . . . .   7
     5.2.  PCEP TLV Type Indicators  . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Additional Stuff . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol PCEP.  PCEP
   defines the communication between a Path Computation Client (PCC) and
   a Path Control Element (PCE), or between PCE and PCE, enabling
   computation of Multi-protocol Label Switching (MPLS) for Traffic
   Engineering Label Switched Path (TE LSP) characteristics.

   Stateful PCE [ietf-pce-stateful-pce] specifies a set of extensions to
   PCEP to enable stateful control of paths such as MPLS TE LSPs between
   and across PCEP sessions in compliance with [RFC4657].  It includes
   mechanisms to effect LSP state synchronization between PCCs and PCEs
   and allow delegation of control of LSPs to PCEs.

   In a network where all LSPs have control delegated to a PCE, the PCE
   can apply global concurrent optimization to optimize LSP placement.
   The PCE can also control the timing and sequence of path computation
   and applying path changes.  In a deployment where a PCE is used to
   compute all the paths, it may be beneficial for the protection paths
   to also be controlled through the PCE.  This document defines
   extensions needed for the setup and management of protection paths by
   the PCE.




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   Benefits of stateful syncrhonization and control of the protection
   paths include:

   o Better control over traffic after a failure and more deterministic
   path computation of protection paths.  The PCE can optimize the
   protection path based on data not available to the PCC, for instance
   the PCE can make sure the protection path will not violate the delay
   specified by [I-D.ietf-pce-pcep-service-aware].

   o Satisfy more complex constraints and diversity requirements, such
   as maintaining diverse paths for LSPs as well as their local
   protection paths.

   o Given the PCE's global view of network resources, act as a form of
   LSP admission control into a protection path to ensure links are not
   overloaded during failure events.

   o On a PLR with multiple available protection routes, allows the PCE
   to map LSPs to all available protection routes versus a single best
   protection route.

   o Most of the benefits stated in the stateful PCE applicability draft
   [I-D.ietf-pce-stateful-pce-app-04] apply equally to protection paths.

2.  Terminology

   This document uses the following terms defined in [RFC5440] PCC PCE,
   PCEP Peer.

   This document uses the following terms defined in Stateful PCE
   [ietf-pce-stateful-pce] : Stateful PCE, Delegation, Delegation
   Timeout Interval, LSP State Report, LSP Update Request.

   The message formats in this document are specified using Routing
   Backus-Naur Format (RBNF) encoding as specified in RFC5511.

3.  Architectural Overview

3.1.  Local Protection Overview

   Local protection refers to the ability to locally route around
   failure of an LSP.  Two types of local protection are possible:

   (1) 1:1 protection - the protection path protects a single LSP.

   (2) N:1 protection - the protection path protects multiple LSPs
   traversing the protected resource.




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   It is assumed that the PCE knows what resources require protection
   through mechanisms outside the scope of this document.  In a PCE
   controlled deployment, support of 1:1 protection has limited
   applicability, and can be achieved as a degenerate case of 1:N
   protection.  For this reason, local protection will be discussed only
   for the N:1 case.

   Local protection requires the setup of a bypass at the PLR.  This
   bypass can be PCC-initiated and delegated, or PCE-initiated.  In
   either case, the PLR MUST maintain a PCEP session to the PCE.  A
   bypass identifier (the name of the bypass) is required for
   disambiguation as multiple bypasses are possible at the PLR.  There
   two types Bypass LSPs mappings:

   (1) Independent Bypass LSP Mapping: In this case Bypass LSP mapping
   is handled by a local policy on PCC and the PCC reports all mappings
   to the PCE.  In other words, bypass LSP(s) are mapped to any
   protected LSP(s) that satisfy PCC local policy.

   (2) Dependent Bypass LSP mapping: Mapping of LSPs to bypass is done
   through a new TLV, the LOCALLY-PROTECTED-LSPS TLV in the LSP Update
   message from PCE to PLR.  See section Section 4.3.  When an LSP
   requiring protection is set up through the PLR, the PLR checks if it
   has a mapping to a bypass and only provides protection if such a
   mapping exists.  The status of bypasses and what LSPs are protected
   by them is communicated to the PCE via LSP Status Report messages.

4.  Extensions for the LSPA object

4.1.  The Weight TLV

   This TLV will be discussed in a future version of this document.

4.2.  The Bypass TLV

   The facility backup method creates a bypass tunnel to protect a
   potential failure point.  The bypass tunnel protects a set of LSPs
   with similar backup constraints [RFC4090].

   A PCC can delegate a bypass tunnel to PCE control or a PCE can
   provision the bypass tunnel via a PCC.  The procedures for bypass
   instantiation rely on the extensions defined in PCE-Initated LSP
   [ietf-pce-pce-initiated-lsp] and will be detailed in a future version
   of this document.

   The Bypass TLV carries information about the bypass tunnel.  It is
   included in the LSPA Object in LSP State Report and LSP Update
   Request messages.



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   The format of the IPv4 Bypass TLV is shown in the following figure:

        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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Type=[TBD]          |           Length=8            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          MUST be zero         |           Flags           |I|N|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Bypass IPv4 Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 1: IPv4 Bypass TLV format

   The type of the TLV is [TBD] and it has a fixed length of 8 octets.
   The value contains the following fields:

   Flags (16 bit)

   N (Node Protection - 1 bit): The N flag indicates whether the Bypass
   is used for node-protection.  If the N flag is set to 1, the Bypass
   is used for node-protection.  If the N flag is 0, the Bypass is used
   for link-protection.

   I (Local Protection In Use - 1 bit): The I Flag indicates that local
   repair mechanism is in use.

   Bypass IPv4 address: For link protection, the Bypass IPv4 Address is
   the nexthop address of the protected link in the paths of the
   protected LSPs.  For node protection, the Bypass IPv4 Address is the
   node addresses of the protected node.

   If the Bypass TLV is included, then the LSPA object MUST also carry
   the SYMBOLIC-PATH-NAME TLV as one of the optional TLVs.  Failure to
   include the mandatory SYMBOLIC-PATH-NAME TLV MUST trigger PCErr of
   type 6 (Mandatory Object missing) and value TBD (SYMBOLIC-PATH-NAME
   TLV missing for bypass LSP)

4.3.  The LOCALLY-PROTECTED-LSPS TLV

   The IPV4-LOCALLY-PROTECTED-LSPS TLV in the LSPA Object contains a
   list of LSPs protected by the bypass tunnel.

   The format of the Locally protected LSPs TLV is shown in the
   following figure:






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        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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Type=[TBD]          |       Length (variable)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   IPv4 tunnel end point address               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Flags            |R|           Tunnel ID           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Extended Tunnel ID                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   IPv4 Tunnel Sender Address                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          MUST be zero         |            LSP ID             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       //                            ....                             //
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   IPv4 tunnel end point address               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Flags            |R|           Tunnel ID           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Extended Tunnel ID                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   IPv4 Tunnel Sender Address                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          MUST be zero         |            LSP ID             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2: IPv4 Locally protected LSPs TLV format

   The type of the TLV is [TBD] and it is of variable length.The value
   contains one or more LSP descriptors including the following fields
   filled per [RFC3209]

   IPv4 Tunnel end point address: As defined in [RFC3209],
   Section 4.6.1.1

   Flags (16 bit)

   R(Remove - 1 bit): The R flag indicates that the LSP has been removed
   from the list of LSPs protected by the bypass tunnel.

   Tunnel ID: As defined in [RFC3209], Section 4.6.1.1

   Extended Tunnel ID: As defined in [RFC3209], Section 4.6.2.1

   IPv4 Tunnel Sender address: As defined in [RFC3209], Section 4.6.2.1




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   LSP ID: As defined in RFC 3209

5.  IANA considerations

5.1.  PCEP-Error Object

   This document defines new Error-Type and Error-Value for the
   following new error conditions:

   Error-Type Meaning 6 Mandatory Object missing Error-value=TBD:
   SYMBOLIC-PATH-NAME TLV missing for a path where the S-bit is set in
   the LSPA object.  Error-value=TBD: SYMBOLIC-PATH-NAME TLV missing for
   a bypass path.

5.2.  PCEP TLV Type Indicators

   This document defines the following new PCEP TLVs:

           +---------+------------------------+---------------+
           | Value # |        Meaning         |   Reference   |
           +---------+------------------------+---------------+
           |   ???   |         Bypass         | This Document |
           |   ???   |         Weight         | This Document |
           |   ???   | LOCALLY-PROTECTED-LSPS | This Document |
           +---------+------------------------+---------------+

                          Table 1: New PCEP TLVs

6.  Security Considerations

   The same security considerations apply at the PLR as those describe
   for the head end in PCE Initiated LSPs [ietf-pce-pce-initiated-lsp].

7.  Acknowledgements

   We would like to thank Ambrose Kwong for his contributions to this
   document.

8.  References

8.1.  Normative References

   [ietf-pce-pce-initiated-lsp]
              Crabbe, E., Sivabalan, S., and R. Verga, "PCEP Extensions
              for PCE-initiated LSP Setup in a Stateful PCE Model",
              2014.





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   [ietf-pce-stateful-pce]
              Crabbe, E., Medved, J., Minie, I., and R. Verga, "PCEP
              Extensions for Stateful PCE", 2015.

   [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", September 1997.

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

   [RFC4090]  Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
              Extensions to RSVP-TE for LSP Tunnels", May 2005.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", May 2008.

   [RFC5440]  Vasseur, JP. and JL. Le Roux, "Path Computation Element
              (PCE) Communication Protocol (PCEP)", March 2009.

8.2.  Informative References

   [I-D.narten-iana-considerations-rfc2434bis]
              Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", draft-narten-iana-
              considerations-rfc2434bis-09 (work in progress), March
              2008.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC
              Text on Security Considerations", BCP 72, RFC 3552, July
              2003.

   [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
              Element (PCE)-Based Architecture", August 2006.

   [RFC4657]  Ash, J. and J. Le Roux, "Path Computation Element (PCE)
              Communication Protocol Generic Requirements", September
              2006.






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   [RFC5394]  Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
              "Policy-Enabled Path Computation Framework", December
              2008.

   [RFC5557]  Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
              Computation Element Communication Protocol (PCEP)
              Requirements and Protocol Extensions in Support of Global
              Concurrent Optimization", July 2009.

Appendix A.  Additional Stuff

   This becomes an Appendix.

Authors' Addresses

   Colby Barth
   Juniper Networks
   Sunnyvale, CA
   USA

   Email: cbarth@juniper.net


   Raveendra Torvi
   Juniper Networks
   Sunnyvale, CA
   USA

   Email: rtorvi@juniper.net


   Phil Bedard
   Cox Communications
   Atlanta, GA
   USA

   Email: Phil.Bedard@cox.com














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