[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05

PCE Working Group                                            A. Raghuram
Internet-Draft                                                A. Goddard
Intended status: Standards Track                           C. Yadlapalli
Expires: January 17, 2018                                           AT&T
                                                              J. Karthik
                                                            S. Sivabalan
                                                               J. Parker
                                                     Cisco Systems, Inc.
                                                                D. Dhody
                                                     Huawei Technologies
                                                           July 16, 2017


   Ability for a stateful PCE to request and obtain control of a LSP
                 draft-raghu-pce-lsp-control-request-04

Abstract

   The stateful Path Computation Element (PCE) communication Protocol
   (PCEP) extensions provide stateful control of Multiprotocol Label
   Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP)
   via PCEP, for a model where a Path Computation Client (PCC) delegates
   control over one or more locally configured LSPs to a stateful PCE.
   There are use-cases in which a stateful PCE may wish to request and
   obtain control of one or more LSPs from a PCC.  This document
   describes a simple extension to stateful PCEP to achieve such an
   objective.

Requirements Language

   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].

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."



Raghuram, et al.        Expires January 17, 2018                [Page 1]


Internet-Draft             LSP Control Request                 July 2017


   This Internet-Draft will expire on January 17, 2018.

Copyright Notice

   Copyright (c) 2017 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  LSP Control Request Flag  . . . . . . . . . . . . . . . . . .   4
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  SRP Object Flags  . . . . . . . . . . . . . . . . . . . .   5
   7.  Manageability Considerations  . . . . . . . . . . . . . . . .   6
     7.1.  Control of Function and Policy  . . . . . . . . . . . . .   6
     7.2.  Information and Data Models . . . . . . . . . . . . . . .   6
     7.3.  Liveness Detection and Monitoring . . . . . . . . . . . .   6
     7.4.  Verify Correct Operations . . . . . . . . . . . . . . . .   6
     7.5.  Requirements On Other Protocols . . . . . . . . . . . . .   6
     7.6.  Impact On Network Operations  . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Stateful PCEP extensions [I-D.ietf-pce-stateful-pce] specifies a set
   of extensions to PCEP [RFC5440] to enable stateful control of TE LSPs
   between and across PCEP sessions in compliance with [RFC4657].  It
   includes mechanisms to effect LSP state synchronization between PCCs
   and PCEs, delegation of control of LSPs to PCEs, and PCE control of
   timing and sequence of path computations within and across PCEP




Raghuram, et al.        Expires January 17, 2018                [Page 2]


Internet-Draft             LSP Control Request                 July 2017


   sessions.  The stateful PCEP defines the following two useful network
   operations:

   o  Delegation: As per [RFC8051], an operation to grant a PCE
      temporary rights to modify a subset of LSP parameters on one or
      more LSPs of a PCC.  LSPs are delegated from a PCC to a PCE and
      are referred to as "delegated" LSPs.

   o  Revocation: As per [I-D.ietf-pce-stateful-pce], an operation
      performed by a PCC on a previously delegated LSP.  Revocation
      revokes the rights granted to the PCE in the delegation operation.

   For Redundant Stateful PCEs (section 5.7.4. of
   [I-D.ietf-pce-stateful-pce]), during a PCE failure, one of the
   redundant PCE could request to take control over an LSP.  The
   redundant PCEs MAY use a local policy or a proprietary election
   mechanism to decide which PCE would take control.  In this case, a
   mechanism is needed for a stateful PCE to request control of one or
   more LSPs from a PCC, so that a newly elected primary PCE can request
   to take over control.

   In case of virtualized PCEs (vPCE) running as virtual network
   function (VNF), as the computation load in the network increases, a
   new instance of vPCE could be instantiated to balance the current
   load.  The PCEs could use proprietary algorithm to decide which LSPs
   to be assigned to the new vPCE.  Thus having a mechanism for the PCE
   to request control of some LSPs is needed.

   In some deployments, the operator would like to use stateful PCE for
   global optimization algorithms but would still like to keep the
   control of the LSP at the PCC.  In such cases, a stateful PCE could
   request to take control during the global optimization and return the
   delegation once done.

   This specification provides a simple extension, by using this a PCE
   can request control of one or more LSPs from any PCC over the
   stateful PCEP channel.  The procedures for granting and relinquishing
   control of the LSPs are specified in accordance with the
   specification [I-D.ietf-pce-stateful-pce].

2.  Terminology

   The following terminologies are used in this document:

   PCC:  Path Computation Client.

   PCE:  Path Computation Element




Raghuram, et al.        Expires January 17, 2018                [Page 3]


Internet-Draft             LSP Control Request                 July 2017


   PCEP:  Path Computation Element communication Protocol.

   PCRpt:  Path Computation State Report message.

   PCUpd:  Path Computation Update Request message.

   PLSP-ID:  A PCEP-specific identifier for the LSP.

3.  LSP Control Request Flag

   The Stateful PCE Request Parameters (SRP) object is defined in
   [I-D.ietf-pce-stateful-pce], it includes a Flags field.
   [I-D.ietf-pce-pce-initiated-lsp] defines a R (LSP-REMOVE) flag.

   A new flag, the "LSP Control Request Flag" (C), is introduced in the
   SRP object.  On a PCUpd message, a PCE sets the C Flag to 1 to
   indicate that, it wishes to gain control of LSP(s).  The LSP is
   identified by the LSP object.  A PLSP-ID of value other than 0 and
   0xFFFFF is used to identify the LSP for which the PCE requests
   control.  The PLSP-ID value of 0 indicates that the PCE is requesting
   control of all LSPs originating from the PCC that it wishes to
   delegate.  The flag has no meaning in the PCRpt and PCInitiate
   message and SHOULD be set to 0 on transmission and MUST be ignored on
   receipt.

4.  Operation

   During normal operation, a PCC that wishes to delegate the control of
   an LSP sets the D Flag to 1 in all PCRpt messages pertaining to the
   LSP.  The PCE confirms the delegation by setting D Flag to 1 in all
   PCUpd messages pertaining to the LSP.  The PCC revokes the control of
   the LSP from the PCE by setting D Flag to 0 in PCRpt messages
   pertaining to the LSP.  If the PCE wishes to relinquish the control
   of the LSP, it sets D Flag to 0 in all PCUpd messages pertaining to
   the LSP.

   If a PCE wishes to gain control over an LSP, it sends a PCUpd message
   with C Flag set to 1 in SRP object.  The LSP for which the PCE
   requests control is identified by the PLSP-ID.  The PLSP-ID of 0
   indicates that the PCE wants control over all LSPs originating from
   the PCC.  If the LSP(s) is/are already delegated to the PCE making
   the request, the PCC ignores the C Flag.  A PCC can decide to
   delegate the control of the LSP at its own discretion.  If the PCC
   grants or denies the control, it sends PCRpt message with D Flag set
   to 1 and 0 respectively in accordance with according with stateful
   PCEP [I-D.ietf-pce-stateful-pce] . If the PCC does not grant the
   control, it MAY choose to not respond, and the PCE may choose to




Raghuram, et al.        Expires January 17, 2018                [Page 4]


Internet-Draft             LSP Control Request                 July 2017


   retry requesting the control preferably using exponentially
   increasing timer.  A PCE ignores the C Flag on the PCRpt message.

   In case multiple PCEs request control over an LSP, and if the PCC is
   willing to grant the control, the LSP MUST be delegated to only one
   PCE chosen by the PCC based on its local policy.

   It should be noted that a legacy implementation of PCC, that does not
   understand the C flag in PCUpd message, would simply ignore the flag
   and the request to grant control over the LSP.

   [I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and
   teardown of PCE-initiated LSPs under the stateful PCE model.  It also
   specify how a PCE MAY obtain control over an orphaned LSP that was
   PCE-initiated.  A PCE implementation can apply the mechanism
   described in this document in conjunction with those in
   [I-D.ietf-pce-pce-initiated-lsp].

5.  Security Considerations

   The security considerations listed in [I-D.ietf-pce-stateful-pce]
   apply to this document as well.  However, this document also
   introduces a new attack vectors.  An attacker may flood the PCC with
   request to delegate all its LSPs at a rate which exceeds the PCC's
   ability to process them, either by spoofing messages or by
   compromising the PCE itself.  The PCC can simply ignore these
   messages with no extra actions.  Securing the PCEP session using
   mechanism like Transport Layer Security (TLS) [I-D.ietf-pce-pceps] is
   RECOMMENDED.

6.  IANA Considerations

   This document requests IANA actions to allocate code points for the
   protocol elements defined in this document.

6.1.  SRP Object Flags

   The SRP object is defined in [I-D.ietf-pce-stateful-pce] and the
   registry to manage the Flag field of the SRP object is requested in
   [I-D.ietf-pce-pce-initiated-lsp].  IANA is requested to make the
   following allocation in the aforementioned registry.

       Bit            Description                      Reference
       TBD            LSP Control Request Flag (c-bit) This document







Raghuram, et al.        Expires January 17, 2018                [Page 5]


Internet-Draft             LSP Control Request                 July 2017


7.  Manageability Considerations

   All manageability requirements and considerations listed in [RFC5440]
   and [I-D.ietf-pce-stateful-pce] apply to PCEP protocol extensions
   defined in this document.  In addition, requirements and
   considerations listed in this section apply.

7.1.  Control of Function and Policy

   A PCE or PCC implementation SHOULD allow the operator to configure
   the policy based on which it honor the request to control the LSPs.
   Further, the operator MAY be to be allowed to trigger the LSP control
   request at the PCE.

7.2.  Information and Data Models

   The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to
   include mechanism to trigger the LSP control request.

7.3.  Liveness Detection and Monitoring

   Mechanisms defined in this document do not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in [RFC5440].

7.4.  Verify Correct Operations

   Mechanisms defined in this document do not imply any new operation
   verification requirements in addition to those already listed in
   [RFC5440] and [I-D.ietf-pce-stateful-pce].

7.5.  Requirements On Other Protocols

   Mechanisms defined in this document do not imply any new requirements
   on other protocols.

7.6.  Impact On Network Operations

   Mechanisms defined in [RFC5440] and [I-D.ietf-pce-stateful-pce] also
   apply to PCEP extensions defined in this document.  Further, the
   mechanism described in this document can help the operator to request
   control of the LSPs at a particular PCE.

8.  Acknowledgements

   Thanks to Jonathan Hardwick to remind the authors to not use
   suggested values in IANA section.




Raghuram, et al.        Expires January 17, 2018                [Page 6]


Internet-Draft             LSP Control Request                 July 2017


9.  References

9.1.  Normative References

   [I-D.ietf-pce-stateful-pce]
              Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-21 (work in progress), June 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <http://www.rfc-editor.org/info/rfc5440>.

9.2.  Informative References

   [I-D.ietf-pce-pce-initiated-lsp]
              Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
              Extensions for PCE-initiated LSP Setup in a Stateful PCE
              Model", draft-ietf-pce-pce-initiated-lsp-10 (work in
              progress), June 2017.

   [I-D.ietf-pce-pcep-yang]
              Dhody, D., Hardwick, J., Beeram, V., and j.
              jefftant@gmail.com, "A YANG Data Model for Path
              Computation Element Communications Protocol (PCEP)",
              draft-ietf-pce-pcep-yang-05 (work in progress), June 2017.

   [I-D.ietf-pce-pceps]
              Lopez, D., Dios, O., Wu, Q., and D. Dhody, "Secure
              Transport for PCEP", draft-ietf-pce-pceps-14 (work in
              progress), May 2017.

   [RFC4657]  Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol Generic
              Requirements", RFC 4657, DOI 10.17487/RFC4657, September
              2006, <http://www.rfc-editor.org/info/rfc4657>.

   [RFC8051]  Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
              Stateful Path Computation Element (PCE)", RFC 8051,
              DOI 10.17487/RFC8051, January 2017,
              <http://www.rfc-editor.org/info/rfc8051>.




Raghuram, et al.        Expires January 17, 2018                [Page 7]


Internet-Draft             LSP Control Request                 July 2017


Authors' Addresses

   Aswatnarayan Raghuram
   AT&T
   200 S Laurel Aevenue
   Middletown, NJ  07748
   USA

   Email: ar2521@att.com


   Al Goddard
   AT&T
   200 S Laurel Aevenue
   Middletown, NJ  07748
   USA

   Email: ag6941@att.com


   Chaitanya Yadlapalli
   AT&T
   200 S Laurel Aevenue
   Middletown, NJ  07748
   USA

   Email: cy098d@att.com


   Jay Karthik
   Cisco Systems, Inc.
   125 High Street
   Boston, Massachusetts  02110
   USA

   Email: jakarthi@cisco.com


   Siva Sivabalan
   Cisco Systems, Inc.
   2000 Innovation Drive
   Kanata, Ontario  K2K 3E8
   Canada

   Email: msiva@cisco.com






Raghuram, et al.        Expires January 17, 2018                [Page 8]


Internet-Draft             LSP Control Request                 July 2017


   Jon Parker
   Cisco Systems, Inc.
   2000 Innovation Drive
   Kanata, Ontario  K2K 3E8
   Canada

   Email: jdparker@cisco.com


   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   Email: dhruv.ietf@gmail.com



































Raghuram, et al.        Expires January 17, 2018                [Page 9]


Html markup produced by rfcmarkup 1.124, available from https://tools.ietf.org/tools/rfcmarkup/