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Versions: (draft-vasseur-ccamp-te-node-cap) 00 01 02 03 04 05 RFC 5073

Network Working Group                              J.P. Vasseur (Editor)
                                                     Cisco Systems, Inc.
IETF Internet Draft                                J.L. Le Roux (Editor)
                                                          France Telecom
Proposed Status: Standard Track                              S. Yasukawa
Expires: May 2007                                                    NTT
                                                              S. Previdi
                                                               P. Psenak
                                                     Cisco Systems, Inc.
                                                              Paul Mabey
                                                                 Comcast





                                                           November 2006


   IGP Routing Protocol Extensions for Discovery of Traffic Engineering
                            Node Capabilities

                  draft-ietf-ccamp-te-node-cap-03.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   http://www.ietf.org/shadow.html.







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Abstract

   It is highly desired in several cases, to take into account Traffic
   Engineering (TE) node capabilities during Multi Protocol Label
   Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineered
   Label Switched Path (TE-LSP)  selection, such as for instance the
   capability to act as a branch Label Switching Router (LSR) of a
   Point-To-MultiPoint (P2MP) LSP. This requires advertising these
   capabilities within the Interior Gateway Protocol (IGP). For that
   purpose, this document specifies Open Shortest Path First (OSPF) and
   Intermediate System-Intermediate System (IS-IS) traffic engineering
   extensions for the advertisement of control plane and data plane
   traffic engineering node capabilities.

Conventions used in this document

   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.

Table of Contents

   1.      Terminology.................................................3
   2.      Introduction................................................3
   3.      TE Node Capability Descriptor...............................4
   3.1.    Description.................................................4
   3.2.    Required Information........................................4
   4.      TE Node Capability Descriptor TLV formats...................5
   4.1.    OSPF TE Node Capability Descriptor TLV format...............5
   4.2.    IS-IS TE Node Capability Descriptor sub-TLV format..........6
   5.      Elements of procedure.......................................7
   5.1.    OSPF........................................................7
   5.2.    IS-IS.......................................................8
   6.      Backward compatibility......................................8
   7.      Security Considerations.....................................9
   8.      IANA considerations.........................................9
   8.1.    OSPF TLV....................................................9
   8.2.    ISIS sub-TLV................................................9
   8.3.    Capability Registry.........................................9
   9.      Acknowledgments............................................10
   10.     References.................................................10
   10.1.   Normative references.......................................10
   10.2.   Informative References.....................................11
   11.     Editors' Addresses.........................................11
   12.     Contributors' Addresses....................................11
   13.     Intellectual Property Statement............................12







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1. Terminology

   This document uses terminologies defined in [RFC3031], [RFC3209] and
   [RFC4461].

2. Introduction

   Multi Protocol Label Switching-Traffic Engineering (MPLS-TE) routing
   ([RFC3784], [RFC3630], [OSPFv3-TE]) relies on extensions to link
   state Interior Gateway Protocols (IGP) ([IS-IS], [RFC2328],
   [RFC2740]) in order to advertise Traffic Engineering (TE) link
   information used for constraint based routing. Further Generalized
   MPLS (GMPLS) related routing extensions are defined in [RFC4205] and
   [RFC4203].

   It is desired to complement these routing extensions in order to
   advertise TE node capabilities, in addition to TE link information.
   These TE node capabilities will be taken into account as constraints
   during path selection.

   Indeed, it is useful to advertise data plane TE node capabilities,
   such as the capability for a Label Switching Router (LSR) to be a
   branch LSR or a bud-LSR of a Point-To-MultiPoint (P2MP) Label
   Switched Path (LSP). These capabilities can then be taken into
   account as constraints when computing the route of TE LSPs.

   It is also useful to advertise control plane TE node capabilities
   such as the capability to support GMPLS signaling for a packet LSR,
   or the capability to support P2MP (Point to Multipoint) TE LSP
   signaling.  This allows selecting a path that avoids nodes that do
   not support a given control plane feature, or triggering a mechanism
   to support such nodes on a path. Hence this facilitates backward
   compatibility.

   For that purpose, this document specifies IGP (OSPF and IS-IS)
   traffic engineering node capability TLVs in order to advertise data
   plane and control plane capabilities of a node.

   A new TLV is defined for ISIS and OSPF: the TE Node Capability
   Descriptor TLV, to be carried within:
        - The ISIS Capability TLV ([ISIS-CAP]) for ISIS
        - The Router Information LSA ([OSPF-CAP]) for OSPF.










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3. TE Node Capability Descriptor

3.1. Description

   LSRs in a network may have distinct control plane and data plane
   Traffic Engineering capabilities. The TE Node Capability Descriptor
   information defined in this document describes data and control plane
   capabilities of an LSR. Such information can be used during path
   computation so as to avoid nodes that do not support a given TE
   feature either in the control or data plane, or to trigger procedures
   to handle these nodes along the path (e.g, trigger LSP hierarchy to
   support a legacy transit LSR on a P2MP LSP (see [RSVP-P2MP])).

3.2. Required Information

   The TE Node Capability Descriptor contains a variable length set of
   bit flags, where each bit corresponds to a given TE node capability.

   Five TE Node Capabilities are defined in this document:

        - B bit: when set, this flag indicates that the LSR can act
                 as a branch node on a P2MP LSP (see [RFC4461]);
        - E bit: when set, this flag indicates that the LSR can act
                 as a bud LSR on a P2MP LSP, i.e. an LSR that is both
                 transit and egress (see [RFC4461]).
        - M bit: when set, this flag indicates that the LSR supports
                 MPLS-TE signaling ([RFC3209]);
        - G bit: when set this flag indicates that the LSR supports
                 GMPLS signaling ([RFC3473]);
        - P bit: when set, this flag indicates that the LSR supports
                 P2MP MPLS-TE signaling ([RSVP-P2MP]).

   Note that new capability bits may be added in the future if required.




















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4. TE Node Capability Descriptor TLV formats

4.1. OSPF TE Node Capability Descriptor TLV format

   The OSPF TE Node Capability Descriptor TLV is a variable length TLV
   that contains a series of bit flags, where each bit correspond to a
   TE node capability.

   The OSPF TE Node Capability Descriptor TLV is carried within an OSPF
   Router Information LSA which is defined in [OSPF-CAP].

   The format of the OSPF TE Node Capability Descriptor TLV is the same
   as the TLV format used by the Traffic Engineering Extensions to OSPF
   [RFC3630]. That is, the TLV is composed of 2 octets for the type, 2
   octets specifying the length of the value field and a value field.

   The OSPF TE Node Capability Descriptor TLV has the following format:

         TYPE     To be assigned by IANA (suggested value =1).
         LENGTH   Variable (multiple of 4).
         VALUE    Array of units of 32 flags numbered from the most
                  significant bit as bit zero, where each bit represents
                  a TE node capability.

   The following bits are defined:

     Bit       Capabilities

      0      B bit: P2MP Branch Node capability: When set this indicates
             that the LSR can act as a branch node on a P2MP LSP
             [RFC4461].
      1      E bit: P2MP Bud-LSR capability: When set, this indicates
             that the LSR can act as a bud LSR on a P2MP LSP, i.e. an
             LSR that is both transit and egress [RFC4461].
      2      M bit: If set this indicates that the LSR supports MPLS-TE
             signaling ([RFC3209]).
      3      G bit: If set this indicates that the LSR supports GMPLS
             signaling ([RFC3473]).
      4      P bit: If set this indicates that the LSR supports P2MP
             MPLS-TE signaling ([RSVP-P2MP]).

     5-31    Reserved for future assignments by IANA.











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4.2. IS-IS TE Node Capability Descriptor sub-TLV format

   The IS-IS TE Node Capability Descriptor sub-TLV is a variable length
   sub-TLV that contains a series of bit flags, where each bit
   correspond to a TE node capability.

   The IS-IS TE Node Capability Descriptor TLV is carried within an IS-
   IS CAPABILITY TLV which is defined in [OSPF-CAP].

   The format of the IS-IS TE Node Capability sub-TLV is the same as the
   TLV format used by the Traffic Engineering Extensions to IS-IS
   [RFC3784]. That is, the TLV is composed of 1 octet for the type, 1
   octet specifying the TLV length and a value field.

   The IS-IS TE Node Capability Descriptor sub-TLV has the following
   format:

      TYPE:   To be assigned by IANA (Suggested value =1)
      LENGTH: Variable
      VALUE:  Array of units of 8 flags numbered from the most
              significant bit as bit zero, where each bit represents
              a TE node capability.

   The following bits are defined:

     Bit       Capabilities

      0      B bit: P2MP Branch Node capability: When set this indicates
             that the LSR can act as a branch node on a P2MP LSP
             [RFC4461].
      1      E bit: P2MP Bud-LSR capability: When set, this indicates
             that the LSR can act as a bud LSR on a P2MP LSP, i.e. an
             LSR that is both transit and egress [RFC4461].
      2      M bit: If set this indicates that the LSR supports MPLS-TE
             signaling ([RFC3209]).
      3      G bit: If set this indicates that the LSR supports GMPLS
             signaling ([RFC3473]).
      4      P bit: If set this indicates that the LSR supports P2MP
             MPLS-TE signaling ([RSVP-P2MP]).

     5-7    Reserved for future assignments by IANA.












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5. Elements of procedure

5.1. OSPF

   The TE Node Capability Descriptor TLV is advertised, within an OSPFv2
   Router Information LSA (Opaque type of 4 and Opaque ID of 0)
   or an OSPFv3 Router Information LSA (function code of 12) which are
   defined in [OSPF-CAP].  As such, elements of procedure are inherited
   from those defined in [RFC2328], [RFC2740], and [OSPF-CAP].

   The TE Node Capability Descriptor TLV advertises capabilities that
   may be taken into account as constraints during path selection. Hence
   its flooding scope is area-local, and it MUST be carried within
   OSPFv2 type 10 Router Information LSA (as defined in [RFC2370]) or an
   OSPFv3 Router Information LSA with the S1 bit set and the S2 bit
   cleared (as defined in [RFC2740]).

   A router MUST originate a new OSPF router information LSA whenever
   the content of the TE Node Capability Descriptor TLV changes or
   whenever required by the regular OSPF procedure (LSA refresh (every
   LSRefreshTime)).

   The TE Node Capability Descriptor TLV is OPTIONAL and MUST NOT appear
   more than once in an OSPF Router Information LSA. If a TE Node
   Capability Descriptor TLV appears more than once in an OSPF Router
   Information LSA, only the first occurrence MUST be processed and
   other MUST be ignored.

   When an OSPF LSA does not contain any TE Node capability Descriptor
   TLV, this means that the TE Capabilities of that LSR are unknown.

   Note that a change in any of these capabilities MAY trigger CSPF
   computation, but MUST NOT trigger normal SPF computation.

   Note also that TE node capabilities are expected to be fairly static.
   They may change as the result of configuration change, or software
   upgrade. This is expected not to appear more than once a day.
















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5.2. IS-IS

   The TE Node Capability sub-TLV is carried within an IS-IS CAPABILITY
   TLV defined in [IS-IS-CAP]. As such, elements of procedure are
   inherited from those defined in [IS-IS-CAP].

   The TE Node Capability Descriptor TLV advertises capabilities that
   may be taken into account as constraints during path selection. Hence
   its flooding is area-local, and MUST be carried within an IS-IS
   CAPABILITY TLV having the S flag cleared.

   An IS-IS router MUST originate a new IS-IS LSP whenever the content
   of any of the TE Node Capability TLV changes or whenever required by
   the regular IS-IS procedure (LSP refresh).

   The TE Node Capability Descriptor TLV is OPTIONAL and MUST NOT appear
   more than once in an ISIS Router Capability TLV. If a TE Node
   Capability Descriptor TLV appears more than once in an ISIS
   Capability TLV, only the first occurrence MUST be processed, other
   occurrences MUST be ignored.

   When an IS-IS LSP does not contain any TE Node capability Descriptor
   TLV, this means that the TE Capabilities of that LSR are unknown.

   Note that a change in any of these capabilities MAY trigger CSPF
   computation, but MUST NOT trigger normal SPF computation.

   Note also that TE node capabilities are expected to be fairly static.
   They may change as the result of configuration change, or software
   upgrade. This is expected not to appear more than once a day.


6. Backward compatibility

   The TE Node Capability Descriptor TLVs defined in this document do
   not introduce any interoperability issue. For OSPF, a router not
   supporting the TE Node Capability Descriptor TLV will just silently
   ignore the TLV as specified in [OSPF-CAP]. For IS-IS a router not
   supporting the TE Node Capability Descriptor TLV will just silently
   ignore the TLV as specified in [IS-IS-CAP].

   When the TE Node capability Descriptor TLV is absent, this means that
   the TE Capabilities of that LSR are unknown.

   The absence of a word of capability flags in OSPF or an octet of
   capability flags in IS-IS means that these capabilities are unknown.







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7. Security Considerations

   This document specifies the content of the TE Node Capability
   Descriptor TLV in ISIS and OSPF, to be used for (G)MPLS-TE path
   computation. As this TLV is not used for SPF computation or normal
   routing, the extensions specified here have no direct effect on IP
   routing. Tampering with this TLV may have an effect on Traffic
   Engineering computation. Mechanisms defined to secure ISIS Link State
   PDUs [ISIS-HMAC], OSPF LSAs [OSPF-SIG], and their TLVs, can be used
   to secure this TLV as well.

8. IANA Considerations

8.1. OSPF TLV

   IANA is in charge of the assignment of TLV code points for the Router
   Information LSA defined in [OSPF-CAP].
   IANA will assign a new codepoint for the TE Node Capability
   Descriptor TLV defined in this document and carried within the Router
   Information LSA (suggested value = 1).

8.2. ISIS sub-TLV

   IANA is in charge of the assignment of sub-TLV code points for the
   ISIS CAPABILITY TLV defined in [ISIS-CAP].
   IANA will assign a new codepoint for the TE Node Capability
   Descriptor sub-TLV defined in this document, and carried within the
   ISIS CAPABILITY TLV (suggested value = 1).

8.3. Capability Registry

   IANA is requested to manage the space of capability bit flags carried
   within the OSPF and ISIS TE Node Capability Descriptor, numbering
   them in the usual IETF notation starting at zero, with the most
   significant bit as bit zero. A single registry must be defined for
   both protocols.
   New bit numbers may be allocated only by an IETF Consensus action.
   Each bit should be tracked with the following qualities:
      - Bit number
      - Defining RFC
      - Name of bit

   Five TE node capabilities are defined in this document and must be
   assigned by IANA. Here are the suggested values:
      1 : B Bit = P2MP Branch LSR capability ([RFC4461])
      2 : E bit = P2MP Bud LSR capability ([RFC4461])
      3 : M bit = MPLS-TE support ([RFC3209])
      4 : G bit = GMPLS support (RFC3473))
      5 : P bit = P2MP RSVP-TE support ([RSVP-P2MP])




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9. Acknowledgments

   We would like to thank Benoit Fondeviole, Adrian Farrel, Dimitri
   Papadimitriou, Acee Lindem and David Ward for their useful comments
   and suggestions.

   We would also like to thank authors of [RFC4420] and [OSPF-CAP] from
   which some text of this document has been inspired.


10. References

10.1. Normative References

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

   [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998.

   [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
             RFC 2740, December 1999.

   [RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370,
             July 1998.

   [RFC4461] Yasukawa, S., et. al., "Signaling Requirements for Point to
   Multipoint Traffic Engineered MPLS LSPs", RFC4461, April 2006.

   [IS-IS] "Intermediate System to Intermediate System Intra-Domain
   Routing Exchange Protocol " ISO 10589.

   [RFC3630] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
   Extensions to OSPF Version 2", RFC 3630, September 2003.

   [RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic
   Engineering", RFC 3784, June 2004.

   [OSPF-CAP] Lindem, A., Shen, N., Aggarwal, R., Shaffer, S., Vasseur,
   J.P., "Extensions to OSPF for advertising Optional Router
   Capabilities", draft-ietf-ospf-cap, work in progress.

   [IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising
   router information", draft-ietf-isis-caps, work in progress.

   [RFC3567] Li, T. and R. Atkinson, "Intermediate System to
   Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567,
   July 2003.

   [RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with
   Digital Signatures", RFC 2154, June 1997.



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   [RFC3209] Awduche, D., et. al., "RSVP-TE: Extensions to RSVP for LSP
   tunnels", RFC 3209, December 2001.

   [RFC3473] Berger, L, et. al., "GMPLS Signaling RSVP-TE extensions",
   RFC 3473, January 2003.

   [RSVP-P2MP] Aggarwal, Papadimitriou, Yasukawa, et. al. "Extensions to
   RSVP-TE for point-to-multipoint TE LSPs", draft-ietf-mpls-rsvp-te-
   p2mp, work in progress.

10.2. Informative References

   [RFC4203] Kompella, K., Rekhter, Y., "OSPF extensions in support of
   Generalized Multi-protocol Label Switching", RFC4203, October 2005.

   [RFC4205] Kompella, K., Rekhter, Y., "IS-IS extensions in support of
   Generalized Multi-protocol Label Switching", RFC4205, October 2005.

   [RFC4420] Farrel, A., and al., "Encoding of attributes for MPLS LSPs
   establishment Using RSVP-TE", RFC4420, February 2006.


11. Editors' Addresses

   Jean-Philippe Vasseur
   Cisco Systems, Inc.
   1414 Massachusetts Avenue
   Boxborough , MA - 01719
   USA
   Email: jpv@cisco.com

   Jean-Louis Le Roux
   France Telecom
   2, avenue Pierre-Marzin
   22307 Lannion Cedex
   FRANCE
   Email: jeanlouis.leroux@orange-ftgroup.com

12. Contributors' Addresses

   Seisho Yasukawa
   NTT
   3-9-11 Midori-cho,
   Musashino-shi, Tokyo 180-8585, Japan
   Email: s.yasukawa@hco.ntt.co.jp

   Stefano Previdi
   Cisco Systems, Inc
   Via Del Serafico 200
   Roma,   00142
   Italy
   Email: sprevidi@cisco.com

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   Peter Psenak
   Cisco Systems, Inc
   Pegasus Park DE Kleetlaan 6A
   Diegmen,   1831
   BELGIUM
   Email: ppsenak@cisco.com

   Paul Mabbey
   Comcast
   USA


13. Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.

   Disclaimer of Validity

   This document and the information contained herein are provided
   on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
   IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
   WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
   ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
   FOR A PARTICULAR PURPOSE.






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   Copyright Statement

   Copyright (C) The IETF Trust (2006). This document is subject to the
   rights, licenses and restrictions contained in BCP 78, and except as
   set forth therein, the authors retain all their rights.
















































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