Network Working Group                                            J. Dong
Internet-Draft                                                   M. Chen
Intended status: Standards Track                     Huawei Technologies
Expires: January 5, July 9, 2015                                         H. Gredler
                                                  Juniper Networks, Inc.
                                                              S. Previdi
                                                     Cisco Systems, Inc.
                                                             J. Tantsura
                                                                Ericsson
                                                            July 4, 2014
                                                         January 5, 2015

   Distribution of MPLS Traffic Engineering (TE) LSP State using BGP
                 draft-ietf-idr-te-lsp-distribution-01
                 draft-ietf-idr-te-lsp-distribution-02

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
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   This Internet-Draft will expire on January 5, July 9, 2015.

Copyright Notice

   Copyright (c) 2014 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Carrying LSP State Information in BGP . . . . . . . . . . . .   4
     2.1.  LSP Identifier Information  . . . . . . . . . . . . . . .   4
     2.2.  LSP State Information . . . . . . . . . . . . . . . . . .   5
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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
   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 multi-area or multi-AS scenarios, each area or AS can have a child
   PCE to collect the LSP states of its own domain, in addition a parent
   PCE needs to collect the LSP information from multiple child PCEs to
   obtain a global view of LSPs inside and across the domains involved.

   In another network scenario, 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 to some external components
   [I-D.ietf-idr-ls-distribution].  Using the same protocol to collect
   other network layer information would be desirable for 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 Information

   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
   Identifier 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 "Link State NLRI" is defined in
   [I-D.ietf-idr-ls-distribution].  Two new "NLRI Type" are defined for
   TE LSP Identifier Information as following:

   o  NLRI Type = 5: IPv4 TE LSP NLRI

   o  NLRI-Type = 6: IPv6 TE LSP NLRI

   The IPv4 TE LSP NLRI (NLRI Type = 5) 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
     +-+-+-+-+-+-+-+-+
     |  Protocol-ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Identifier                          |
     |                            (64 bits)                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   IPv4 Tunnel Sender Address                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Tunnel ID         |             LSP ID            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  IPv4 Tunnel End-point Address                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 2. IPv4 TE LSP NLRI

   The IPv6 TE LSP NLRI (NLRI Type = 6) 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
     +-+-+-+-+-+-+-+-+
     |  Protocol-ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Identifier                          |
     |                            (64 bits)                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                  IPv6 Tunnel Sender Address                   |
     +                          (16 octets)                          +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Tunnel ID            |             LSP ID            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     +                                                               +
     |                 IPv6 Tunnel End-point Address                 |
     +                          (16 octets)                          +
     |                                                               |
     +                                                               +
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       Figure 3. IPv6 TE LSP NLRI

   For IPv4 TE LSP NLRI and IPv6 TE LSP NLRI, the Protocol-ID field is
   set to 6, which indicates that the NLRI information has been sourced
   by RSVP-TE.

   The Identifier field is used to discriminate between instances with
   different LSP technology - e.g. one identifier can identify the
   instance for packet path, and another one is to identify the instance
   of optical path.

   The other fields in the IPv4 TE LSP NLRI and IPv6 TE LSP NLRI are the
   same as specified in [RFC3209].

2.2.  LSP State Information

   The LSP State TLV is used to describe the characteristics of the TE
   LSPs, which is carried in the optional non-transitive BGP Attribute
   "LINK_STATE Attribute" defined in [I-D.ietf-idr-ls-distribution].

   The "Value" field of the LSP State TLV corresponds to the format and
   semantics of a set of objects defined in [RFC3209], [RFC3473] and
   other extensions for TE LSPs.  Rather than replicating all RSVP-TE
   related objects in this document, the semantics and encodings of
   existing TE LSP objects are re-used.  Hence all TE LSP objects are
   regarded as sub-TLVs.  The LSP State TLV SHOULD only be used with
   IPv4/IPv6 TE 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                   TE LSP Objects (variable)                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   Figure 4. LSP State TLV

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

   o  SENDER_TSPEC and FLOW_SPEC [RFC2205]

   o  SESSION_ATTRIBUTE [RFC3209]

   o  Explicit Route Object (ERO) [RFC3209]

   o  Record Route Object (RRO) [RFC3209]

   o  FAST_REROUTE Object [RFC4090]

   o  DETOUR Object [RFC4090]

   o  EXCLUDE_ROUTE Object (XRO) [RFC4874]

   o  SECONDARY_EXPLICIT_ROUTE Object (SERO) [RFC4873]

   o  SECONDARY_RECORD_ROUTE (SRRO) [RFC4873]

   o  LSP_ATTRIBUTES Object [RFC5420]

   o  LSP_REQUIRED_ATTRIBUTES Object [RFC5420]

   o  PROTECTION Object [RFC3473][RFC4872][RFC4873]

   o  ASSOCIATION Object [RFC4872]
   o  PRIMARY_PATH_ROUTE Object [RFC4872]

   o  ADMIN_STATUS Object [RFC3473]

   o  BANDWIDTH Object [RFC5440]

   o  METRIC Object [RFC5440]

   Other TE LSP objects which reflect specific state or attribute of the
   LSP may also be carried in the LSP state TLV, which is for further
   study.

3.  Operational Considerations

   The Existing BGP operational procedures apply to this document.  No
   new operation procedures are defined in this document.  The
   operational considerations as specified in
   [I-D.ietf-idr-ls-distribution] apply to this document .

4.  IANA Considerations

   IANA needs to assign two code points for "IPv4 TE LSP NLRI" and "IPv6
   TE LSP NLRI" from the BGP-LS registry of NLRI Types.

   IANA needs to assign one Protocol-ID for "RSVP-TE" from the BGP-LS
   registry of Protocol-IDs.

   IANA needs to assign one new TLV type for "LSP State TLV" from the
   registry of BGP-LS Attribute TLVs.

5.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model.  See [RFC6952] for details.

6.  Acknowledgements

   The authors would like to thank Dhruv Dhody and Mohammed Abdul Aziz
   Khalid for their review and valuable comments.

7.  References

7.1.  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-05 draft-ietf-idr-ls-distribution-07
              (work in progress), May November 2014.

   [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.

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

   [RFC4090]  Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
              Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May
              2005.

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

   [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.

   [RFC4874]  Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
              Extension to Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE)", RFC 4874, April 2007.

   [RFC5420]  Farrel, A., Papadimitriou, D., Vasseur, JP., and A.
              Ayyangarps, "Encoding of Attributes for MPLS LSP
              Establishment Using Resource Reservation Protocol Traffic
              Engineering (RSVP-TE)", RFC 5420, February 2009.

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

7.2.  Informative 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-09
              pce-10 (work in progress), June October 2014.

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

   [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
              BGP, LDP, PCEP, and MSDP Issues According to the Keying
              and Authentication for Routing Protocols (KARP) Design
              Guide", RFC 6952, May 2013.

Authors' Addresses

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

   Email: jie.dong@huawei.com

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

   Email: mach.chen@huawei.com

   Hannes Gredler
   Juniper Networks, Inc.
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089
   US

   Email: hannes@juniper.net
   Stefano Previdi
   Cisco Systems, Inc.
   Via Del Serafico, 200
   Rome  00142
   Italy

   Email: sprevidi@cisco.com

   Jeff Tantsura
   Ericsson
   300 Holger Way
   San Jose, CA  95134
   US

   Email: jeff.tantsura@ericsson.com