PCE Working Group                                               U. Palle
Internet-Draft                                                  D. Dhody
Intended status: Standards Track                     Huawei Technologies
Expires: August 18, 2014                                       Y. Tanaka
                                                               Y. Kamite
                                                      NTT Communications
                                                       February 14, 2014


  PCEP Extensions for PCE-initiated Point-to-Multipoint LSP Setup in a
                           Stateful PCE Model
           draft-palle-pce-stateful-pce-initiated-p2mp-lsp-01

Abstract

   The Path Computation Element (PCE) has been identified as an
   appropriate technology for the determination of the paths of point-
   to-multipoint (P2MP) TE LSPs.  The extensions described in
   [I-D.ietf-pce-stateful-pce] provide stateful control of Multiprotocol
   Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE
   LSP) via PCE communication Protocol (PCEP), for a model where the
   Path Computation Client (PCC) delegates control over one or more
   locally configured LSPs to the PCE.  Further
   [I-D.ietf-pce-pce-initiated-lsp] describes the creation and deletion
   of PCE-initiated LSPs under the stateful PCE model.  This document
   provides extensions required for PCEP so as to enable the usage of a
   stateful PCE initiation capability in supporting point-to-multipoint
   (P2MP) TE LSP instantiation.

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 18, 2014.






Palle, et al.            Expires August 18, 2014                [Page 1]


Internet-Draft               INITIATED-P2MP                February 2014


Copyright Notice

   Copyright (c) 2014 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   4
     3.1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Operation Overview  . . . . . . . . . . . . . . . . . . .   4
   4.  Support of PCE Initiated P2MP TE LSPs . . . . . . . . . . . .   5
   5.  PCE-initiated P2MP TE LSP Operations  . . . . . . . . . . . .   5
     5.1.  The PCInitiate message  . . . . . . . . . . . . . . . . .   5
     5.2.  P2MP TE LSP Instantiation . . . . . . . . . . . . . . . .   6
     5.3.  P2MP TE LSP Deletion  . . . . . . . . . . . . . . . . . .   7
     5.4.  Adding and Pruning Leaves for the P2MP TE LSP . . . . . .   7
     5.5.  P2MP TE LSP Delegation and Cleanup  . . . . . . . . . . .   7
   6.  PCIntiate Message Fragmentation . . . . . . . . . . . . . . .   7
     6.1.  PCIntiate Fragmentation Procedure . . . . . . . . . . . .   8
   7.  Non-Support of P2MP TE LSP Instantiation for Stateful PCE . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Manageability Considerations  . . . . . . . . . . . . . . . .   8
     9.1.  Control of Function and Policy  . . . . . . . . . . . . .   8
     9.2.  Information and Data Models . . . . . . . . . . . . . . .   8
     9.3.  Liveness Detection and Monitoring . . . . . . . . . . . .   8
     9.4.  Verify Correct Operations . . . . . . . . . . . . . . . .   9
     9.5.  Requirements On Other Protocols . . . . . . . . . . . . .   9
     9.6.  Impact On Network Operations  . . . . . . . . . . . . . .   9
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informative References . . . . . . . . . . . . . . . . .  10





Palle, et al.            Expires August 18, 2014                [Page 2]


Internet-Draft               INITIATED-P2MP                February 2014


1.  Introduction

   As per [RFC4655], the Path Computation Element (PCE) is an entity
   that is capable of computing a network path or route based on a
   network graph, and applying computational constraints.  A Path
   Computation Client (PCC) may make requests to a PCE for paths to be
   computed.

   [RFC4857]describes how to set up point-to-multipoint (P2MP) Traffic
   Engineering Label Switched Paths (TE LSPs) for use in Multiprotocol
   Label Switching (MPLS) and Generalized MPLS (GMPLS) networks.  The
   PCE has been identified as a suitable application for the computation
   of paths for P2MP TE LSPs ( [RFC5671]).

   The PCEP is designed as a communication protocol between PCCs and
   PCEs for point-to-point (P2P) path computations and is defined in
   [RFC5440].  The extensions of PCEP to request path computation for
   P2MP TE LSPs are described in [RFC6006].

   Stateful PCEs are shown to be helpful in many application scenarios,
   in both MPLS and GMPLS networks, as illustrated in
   [I-D.ietf-pce-stateful-pce-app].  These scenarios apply equally to
   P2P and P2MP TE LSPs.  [I-D.ietf-pce-stateful-pce]provides the
   fundamental extensions needed for stateful PCE to support general
   functionality for P2P TE LSP.  Further
   [I-D.palle-pce-stateful-pce-p2mp]focuses on the extensions that are
   necessary in order for the deployment of stateful PCEs to support
   P2MP TE LSPs.  It includes mechanisms to effect P2MP LSP state
   synchronization between PCCs and PCEs, delegation of control of P2MP
   LSPs to PCEs, and PCE control of timing and sequence of P2MP path
   computations within and across PCEP sessions and focuses on a model
   where P2MP LSPs are configured on the PCC and control over them is
   delegated to the PCE.

   [I-D.ietf-pce-pce-initiated-lsp]provides the fundamental extensions
   needed for stateful PCE-initiated P2P TE LSP instantiation.

   This document describes the setup, maintenance and teardown of PCE-
   initiated P2MP LSPs under the stateful PCE model, without the need
   for local configuration on the PCC, thus allowing for a dynamic
   network that is centrally controlled and deployed.

1.1.  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].




Palle, et al.            Expires August 18, 2014                [Page 3]


Internet-Draft               INITIATED-P2MP                February 2014


2.  Terminology

   Terminology used in this document is same as terminology used in
   [I-D.ietf-pce-stateful-pce], [I-D.ietf-pce-pce-initiated-lsp]and
   [RFC6006].

3.  Architectural Overview

3.1.  Motivation

   [I-D.palle-pce-stateful-pce-p2mp] provides stateful control over P2MP
   TE LSPs that are locally configured on the PCC.  This model relies on
   the Ingress taking an active role in delegating locally configured
   P2MP TE LSPs to the PCE, and is well suited in environments where the
   P2MP TE LSP placement is fairly static.  However, in environments
   where the P2MP TE LSP placement needs to change in response to
   application demands, it is useful to support dynamic creation and
   tear down of P2MP TE LSPs.  The ability for a PCE to trigger the
   creation of P2MP TE LSPs on demand can be seamlessly integrated into
   a controller-based network architecture, where intelligence in the
   controller can determine when and where to set up paths.

   Section 3 of [I-D.ietf-pce-pce-initiated-lsp]further describes the
   motivation behind the PCE-Initiation capability, which are equally
   applicable for P2MP TE LSPs.

3.2.  Operation Overview

   A PCC or PCE indicates its ability to support PCE provisioned dynamic
   LSPs and P2MP operations during the PCEP Initialization Phase via
   mechanism described in Section 4.

   As per section 5.1 of [I-D.ietf-pce-pce-initiated-lsp], the PCE sends
   a Path Computation LSP Initiate Request (PCInitiate) message to the
   PCC to instantiate or delete a P2P TE LSP.  This document extends the
   PCInitiate message to support P2MP TE LSP Instantiation (see details
   in Section 5.1).

   P2MP TE LSP instantiation and deletion operations are same as P2P LSP
   Instantiation as described in section 5.3 and 5.4 of
   [I-D.ietf-pce-pce-initiated-lsp].  This document focuses on
   extensions needed for further handling of P2MP TE LSP Instantiation
   (see details in Section 5.2).








Palle, et al.            Expires August 18, 2014                [Page 4]


Internet-Draft               INITIATED-P2MP                February 2014


4.  Support of PCE Initiated P2MP TE LSPs

   As per Section 3.1 of [RFC6006], PCE advertises P2MP capability via
   IGP discovery or a P2MP capable TLV in open message.  To support
   instantiation of PCE-initiated P2MP TE LSPs, this document extends
   the advertisement of P2MP capable TLV in open message by all PCEP
   speakers.  As per Section 4 of [I-D.ietf-pce-pce-initiated-lsp], PCC
   or PCE advertises capability for instantiation of PCE-initiated LSPs
   via Stateful PCE Capability TLV (LSP-INSTANTIATION-CAPABILITY bit) in
   open message.  These mechanism when used together indicates the
   instantiation capability for P2MP TE LSPs by the PCEP speaker.

5.  PCE-initiated P2MP TE LSP Operations

5.1.  The PCInitiate message

   As defined in section 5.1 of [I-D.ietf-pce-pce-initiated-lsp], PCE
   sends a PCInitiate message to a PCC to instantiate a P2P TE LSP, this
   document extends the format of PCInitiate message for the creation of
   P2MP TE LSPs but the creation and deletion operations of P2MP TE LSP
   are same to the P2P TE LSP.

   The format of PCInitiate message is as follows:




























Palle, et al.            Expires August 18, 2014                [Page 5]


Internet-Draft               INITIATED-P2MP                February 2014


   <PCInitiate Message> ::= <Common Header>
                            <PCE-initiated-lsp-list>
   Where:

   <PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
                                [<PCE-initiated-lsp-list>]

   <PCE-initiated-lsp-request> ::=
   (<PCE-initiated-lsp-instantiation>|<PCE-initiated-lsp-deletion>)

   <PCE-initiated-lsp-instantiation> ::= <SRP>
                                         <LSP>
                                         <end-point-path-pair-list>
                                         [<attribute-list>]

   <PCE-initiated-lsp-deletion> ::= <SRP>
                                    <LSP>

   Where:

   <end-point-path-pair-list>::=
                      [<END-POINTS>]
                      <path>
                      [<end-point-path-pair-list>]

   <path> ::= (<ERO>|<SERO>)
              [<path>]

   <attribute-list> is defined in [RFC5440] and extended
   by PCEP extensions.


   The PCInitiate message with an LSP object with N bit (P2MP) set is
   used to convey operation on a P2MP TE LSP.  The SRP object is used to
   correlate between initiation requests sent by the PCE and the error
   reports and state reports sent by the PCC as described in
   [I-D.ietf-pce-stateful-pce].

5.2.  P2MP TE LSP Instantiation

   The Instantiation operation of P2MP TE LSP is same as defined in
   section 5.3 of [I-D.ietf-pce-pce-initiated-lsp] including handling of
   PLSP-ID, SYMBOLIC-PATH-NAME etc.  Rules of processing and error codes
   remains unchanged.  Further, as defined in section 6.1 of
   [I-D.palle-pce-stateful-pce-p2mp], N bit MUST be set in LSP object in
   PCInitiate message by PCE to specify the instantiation is for P2MP TE
   LSP and the PCC or PCE MUST follow the mechanism defined in




Palle, et al.            Expires August 18, 2014                [Page 6]


Internet-Draft               INITIATED-P2MP                February 2014


   [I-D.palle-pce-stateful-pce-p2mp] for delegation and updation of P2MP
   TE LSPs.

   Though N bit is set in the LSP object, P2MP-LSP-IDENTIFIER TLV
   defined in section 6.2 of [I-D.palle-pce-stateful-pce-p2mp] MUST NOT
   be included in the LSP object in PCIntiitate message as it SHOULD be
   generated by PCC and carried in PCRpt message.

5.3.  P2MP TE LSP Deletion

   The deletion operation of P2MP TE LSP is same as defined in section
   5.4 of [I-D.ietf-pce-pce-initiated-lsp] by sending an LSP Initiate
   Message with an LSP object carrying the PLSP-ID of the LSP to be
   removed and an SRP object with the R flag set (LSP-REMOVE as per
   section 5.2 of [I-D.ietf-pce-pce-initiated-lsp]).  Rules of
   processing and error codes remains unchanged.

5.4.  Adding and Pruning Leaves for the P2MP TE LSP

   Adding of new leaves and Pruning of old Leaves for the PCE initiated
   P2MP TE LSP MUST be carried in PCUpd message and SHOULD refer
   [I-D.palle-pce-stateful-pce-p2mp] for P2MP TE LSP extensions.  As
   defined in [RFC6006], leaf type = 1 for adding of new leaves, leaf
   type = 2 for pruning of old leaves of P2MP END-POINTS Object are used
   in PCUpd message.

5.5.  P2MP TE LSP Delegation and Cleanup

   P2MP TE LSP delegation and cleanup operations are same as defined in
   section 6 of [I-D.ietf-pce-pce-initiated-lsp].  Rules of processing
   and error codes remains unchanged.

6.  PCIntiate Message Fragmentation

   The total PCEP message length, including the common header, is 16
   bytes.  In certain scenarios the P2MP LSP Initiate may not fit into a
   single PCEP message (initial PCInitiate message).  The F-bit is used
   in the LSP object to signal that the initial PCInitiate was too large
   to fit into a single message and will be fragmented into multiple
   messages.

   Fragmentation procedure described below for PCInitiate message is
   similar to [RFC6006] which describes request and response message
   fragmentation.







Palle, et al.            Expires August 18, 2014                [Page 7]


Internet-Draft               INITIATED-P2MP                February 2014


6.1.  PCIntiate Fragmentation Procedure

   Once the PCE initiates to set up the P2MP TE LSP, a PCInitiate
   message is sent to the PCC.  If the PCInitiate is too large to fit
   into a single PCInitiate message, the PCE will split the PCInitiate
   over multiple messages.  Each PCInitiate message sent by the PCE,
   except the last one, will have the F-bit set in the LSP object to
   signify that the PCInitiate has been fragmented into multiple
   messages.  In order to identify that a series of PCInitiate messages
   represents a single Initiate, each message will use the same PLSP-ID
   (in this case 0) and SRP-ID-number.

   [Editor Note: P2MP message fragmentation errors associated with a
   P2MP path initiation will be defined in future version].

7.  Non-Support of P2MP TE LSP Instantiation for Stateful PCE

   The PCEP protocol extensions described in this document for PCC or
   PCE with instantiation capability for P2MP TE LSPs MUST NOT be used
   if PCC or PCE has not advertised its stateful capability with
   Instantiation and P2MP capability as per Section 4.  If this is not
   the case and Stateful operations on P2MP TE LSPs are attempted, then
   a PCErr with error-type 19 (Invalid Operation) and error-value TBD
   needs to be generated.

   [Editor Note: more information on exact error value is needed]

8.  Security Considerations

   TBD

9.  Manageability Considerations

9.1.  Control of Function and Policy

   TBD.

9.2.  Information and Data Models

   TBD.

9.3.  Liveness Detection and Monitoring

   TBD.







Palle, et al.            Expires August 18, 2014                [Page 8]


Internet-Draft               INITIATED-P2MP                February 2014


9.4.  Verify Correct Operations

   TBD.

9.5.  Requirements On Other Protocols

   TBD.

9.6.  Impact On Network Operations

   TBD.

10.  IANA Considerations

   TBD

11.  Acknowledgments

   TBD

12.  References

12.1.  Normative References

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

   [RFC5440]  Vasseur, JP. and JL. Le Roux, "Path Computation Element
              (PCE) Communication Protocol (PCEP)", RFC 5440, March
              2009.

   [I-D.ietf-pce-stateful-pce]
              Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-07 (work in progress), October 2013.

   [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-00 (work in
              progress), December 2013.

   [I-D.palle-pce-stateful-pce-p2mp]
              Palle, U. and D. Dhody, "Path Computation Element (PCE)
              Protocol Extensions for Stateful PCE usage for Point-to-
              Multipoint Traffic Engineering Label Switched Paths",
              draft-palle-pce-stateful-pce-p2mp-01 (work in progress),
              January 2014.



Palle, et al.            Expires August 18, 2014                [Page 9]


Internet-Draft               INITIATED-P2MP                February 2014


12.2.  Informative References

   [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
              Element (PCE)-Based Architecture", RFC 4655, August 2006.

   [RFC4857]  Fogelstroem, E., Jonsson, A., and C. Perkins, "Mobile IPv4
              Regional Registration", RFC 4857, June 2007.

   [RFC5671]  Yasukawa, S. and A. Farrel, "Applicability of the Path
              Computation Element (PCE) to Point-to-Multipoint (P2MP)
              MPLS and GMPLS Traffic Engineering (TE)", RFC 5671,
              October 2009.

   [RFC6006]  Zhao, Q., King, D., Verhaeghe, F., Takeda, T., Ali, Z.,
              and J. Meuric, "Extensions to the Path Computation Element
              Communication Protocol (PCEP) for Point-to-Multipoint
              Traffic Engineering Label Switched Paths", RFC 6006,
              September 2010.

   [I-D.ietf-pce-stateful-pce-app]
              Zhang, X. and I. Minei, "Applicability of Stateful Path
              Computation Element (PCE)", draft-ietf-pce-stateful-pce-
              app-01 (work in progress), September 2013.

Authors' Addresses

   Udayasree Palle
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA

   EMail: udayasree.palle@huawei.com


   Dhruv Dhody
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA

   EMail: dhruv.ietf@gmail.com









Palle, et al.            Expires August 18, 2014               [Page 10]


Internet-Draft               INITIATED-P2MP                February 2014


   Yosuke Tanaka
   NTT Communications Corporation
   Granpark Tower
   3-4-1 Shibaura, Minato-ku
   Tokyo  108-8118
   Japan

   EMail: yosuke.tanaka@ntt.com


   Yuji Kamite
   NTT Communications Corporation
   Granpark Tower
   3-4-1 Shibaura, Minato-ku
   Tokyo  108-8118
   Japan

   EMail: y.kamite@ntt.com

































Palle, et al.            Expires August 18, 2014               [Page 11]