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Versions: 00 01 02 03 04                                                
Network Working Group                                            J. Dong
Internet-Draft                                                   M. Chen
Intended status: Standards Track                     Huawei Technologies
Expires: August 29, 2013                               February 25, 2013


   Distribution of MPLS Traffic Engineering (TE) LSP State using BGP
                 draft-dong-idr-te-lsp-distribution-01

Abstract

   This document describes a mechanism to collect the Traffic
   Engineering (TE) LSP information using BGP.  Such information can be
   used by external components for path reoptimization, service
   placement and network visualization.

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 RFC 2119 [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."

   This Internet-Draft will expire on August 29, 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



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   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
   2.  Carrying LSP State Information in BGP . . . . . . . . . . . . . 4
     2.1.  LSP Identifier Inforation . . . . . . . . . . . . . . . . . 4
     2.2.  LSP State Attribute . . . . . . . . . . . . . . . . . . . . 6
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 7
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8































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1.  Introduction

   In some network environments, the states of established Multi-
   Protocol Label Switching (MPLS) Traffic Engineering (TE) Label
   Switched Paths (LSPs) in the network are required by some components
   external to the network domain.  Usually this information is directly
   maintained by the ingress Label Edge Routers (LERs) of the MPLS TE
   LSPs.

   One example of using the LSP information is stateful Path Computation
   Element (PCE) [I-D.ietf-pce-stateful-pce], which could provide
   benefits in path reoptimization .  While some extensions are proposed
   in Path Computation Element Communication Protocol (PCEP) for the
   Path Computation Clients (PCCs) to report the LSP states to the PCE,
   this mechanism may not be applicable in a management-based PCE
   architecture as specified in section 5.5 of [RFC4655].  As
   illustrated in the figure below, the PCC is not an LSR in the routing
   domain, thus the head-end nodes of the TE-LSP may not implement the
   PCEP protocol.  In this case some general mechanism to collect the
   TE-LSP states from the ingress LERs is needed.  This document
   proposes an LSP state collection mechanism complementary to the
   mechanism defined in [I-D.ietf-pce-stateful-pce].

                                   -----------
                                  |   -----   |
              Service             |  | TED |<-+----------->
              Request             |   -----   |  TED synchronization
                 |                |     |     |  mechanism (for example,
                 v                |     |     |  routing protocol)
           ------------- Request/ |     v     |
          |             | Response|   -----   |
          |     NMS     |<--------+> | PCE |  |
          |             |         |   -----   |
           -------------           -----------
         Service |
         Request |
                 v
            ----------  Signaling   ----------
           | Head-End | Protocol   | Adjacent |
           |  Node    |<---------->|   Node   |
            ----------              ----------

                 Figure 1.  Management-Based PCE Usage

   In networks with composite PCE nodes as specified in section 5.1 of
   [RFC4655], the PCE is implemented on several routers in the network,
   and the PCCs in the network can use the mechanism described in
   [I-D.ietf-pce-stateful-pce] to report the LSP information to the PCE



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   nodes.  An external component may further need to collect the LSP
   information from all the PCEs in the network to get a global view of
   the LSP states in the network.

   In some networks, a centralized controller is used for service
   placement.  Obtaining the TE LSP state information is quite important
   for making appropriate service placement decisions with the purpose
   of both meeting the application's requirements and utilizing the
   network resource efficiently.

   The Network Management System (NMS) may need to provide global
   visibility of the TE LSPs in the network as part of the network
   visualization function.

   BGP has been extended to distribute link-state and traffic
   engineering information and share with some external components
   [I-D.ietf-idr-ls-distribution].  Using the same protocol to collect
   other network layer information would be desired by the external
   components, which avoids introducing multiple protocols for network
   information collection.  This document describes a mechanism to
   distribute the TE LSP information to external components using BGP.


2.  Carrying LSP State Information in BGP

2.1.  LSP Identifier Inforation

   The TE LSP Identifier information is advertised in BGP UPDATE
   messages using the MP_REACH_NLRI and MP_UNREACH_NLRI attributes
   [RFC4760].  The "Link State NLRI" defined in
   [I-D.ietf-idr-ls-distribution] is extended to carry the TE LSP
   information.  BGP speakers that wish to exchange TE LSP information
   MUST use the BGP Multiprotocol Extensions Capability Code (1) to
   advertise the corresponding (AFI, SAFI) pair, as specified in
   [RFC4760].

   The format of the Link State NLRI 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        NLRI Type              |      Total NLRI Length        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Link State NLRI (variable)                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 2. Link State NLRI Format

   Two new "NLRI Type" are defined for TE LSP Identifier Information as
   following:

   o  NLRI Type = 5: IPv4 LSP NLRI

   o  NLRI-Type = 6: IPv6 LSP NLRI

   If the NLRI Type value is set to 5, the Link State NLRI field is the
   IPv4-LSP-IDENTIFER structured as below:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   IPv4 Tunnel Sender Address                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Tunnel ID         |             LSP ID            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  IPv4 Tunnel End-point Address                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 3. IPv4-LSP-IDENTIFIER

   If the NLRI Type value is set to 6, the Link State NLRI field is the
   IPv6-LSP-IDENTIFIER structured as below:



















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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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                  IPv6 Tunnel Sender Address                   |
     +                          (16 octets)                          +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Tunnel ID            |             LSP ID            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                 IPv6 Tunnel End-point Address                 |
     +                          (16 octets)                          +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 4. IPv6-LSP-IDENTIFIER

   The fields in the IPv4-LSP-IDENTIFIER and IPv6-LSP-IDENTIFIER are the
   same as specified in [RFC3209].

2.2.  LSP State Attribute

   The LSP State Attribute is an optional non-transitive BGP attribute
   which is used to describe the characteristics of the LSPs.  The LSP
   State Attribute consists of a set of objects defined in [RFC3209],
   [RFC3473] and [RFC5440] .  This Attribute SHOULD only be used with
   IPv4/IPv6 LSP NLRI.

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     ~                   Objects (variable)                          ~
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     Figure 5. LSP State Attribute

   Currently the Objects that can be carried in the LSP State Attribute
   include:






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   o  LSP Attributes (LSPA) Object

   o  Explicit Route Object (ERO)

   o  Record Route Object (RRO)

   o  BANDWIDTH Object

   o  METRIC Object

   o  Protection Object

   o  Admin Status Object

   Other objects may also be carried in the LSP State Attribute, which
   would be specified in a future version.


3.  IANA Considerations

   IANA needs to assign an new code point for the LSP State Attribute
   from the "BGP Path Attributes" registry.


4.  Security Considerations

   TBD


5.  Acknowledgements

   TBD


6.  References

6.1.  Normative References

   [I-D.ietf-idr-ls-distribution]
              Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
              Ray, "North-Bound Distribution of Link-State and TE
              Information using BGP", draft-ietf-idr-ls-distribution-01
              (work in progress), October 2012.

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

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,



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              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

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

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              January 2007.

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

6.2.  Informative References

   [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-02 (work in progress),
              October 2012.

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


Authors' Addresses

   Jie Dong
   Huawei Technologies
   Huawei Building, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: jie.dong@huawei.com


   Mach(Guoyi) Chen
   Huawei Technologies
   Huawei Building, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: mach.chen@huawei.com






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