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Versions: (draft-berger-ccamp-swcaps-update) 00 01 02 03 RFC 7074

Internet Draft                                                Lou Berger
Updates: 3471, 4202, 4203, 5307                                   (LabN)
Category: Standards Track                                  Julien Meuric
Expiration Date: February 23, 2014               (France Telecom Orange)

                                                         August 23, 2013

  Revised Definition of The GMPLS Switching Capability and Type Fields

                 draft-ietf-ccamp-swcaps-update-03.txt

Abstract

   GMPLS provides control for multiple switching technologies, and
   hierarchical switching within a technology.  GMPLS routing and
   signaling use common values to indicate switching technology type.
   These values are carried in routing in the Switching Capability
   field, and in signaling in the Switching Type field. While the
   values used in these fields are the primary indicators of the
   technology and hierarchy level being controlled, the values are
   not consistently defined and used across the different
   technologies supported by GMPLS.  This document is intended to
   resolve the inconsistent definition and use of the Switching
   Capability and Type fields by narrowly scoping the meaning and use
   of the fields.  This document updates any document that uses the
   GMPLS Switching Capability and Types fields, in particular RFC
   3471, RFC 4202, RFC 4203, and RFC 5307.

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), its areas, and its working groups.  Note that
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   This Internet-Draft will expire on February 23, 2014




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Copyright and License 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
   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.

1. Introduction

   Generalized Multi-Protocol Label Switching (GMPLS) provides control
   for multiple switching technologies.  It also supports hierarchical
   switching within a technology.  The original GMPLS Architecture, per
   [RFC3945], included support for five types of switching capabilities.
   An additional type was also been defined in [RFC6002].  The switching
   types defined in these documents include:
      1. Packet Switch Capable (PSC)
      2. Layer-2 Switch Capable (L2SC)
      3. Time-Division Multiplex Capable (TDM)
      4. Lambda Switch Capable (LSC)
      5. Fiber-Switch Capable (FSC)
      6. Data Channel Switching Capable (DCSC)

   Support for the original types was defined for routing in [RFC4202],
   [RFC4203], and [RFC5307], where the types were represented in the
   Switching Capability (Switching Cap) field.  In general, hierarchy
   within a type is addressed in a type-specific fashion and a single
   Switching Capability field value is defined per type.  The exception
   to this is PSC which was assigned four values to indicate four levels
   of hierarchy: PSC-1, PSC-2, PSC-3 and PSC-4.  The same values used in
   routing are defined for signaling in [RFC3471], and are carried in
   the Switching Type field. Following the IANA registry, we refer to
   the values used in the routing Switching Capability field and
   signaling Switching Type field as Switching Types.

   In general, a Switching Type does not indicate a specific data plane
   technology, but rather this needs to be inferred from context.  For
   example L2SC was defined to cover Ethernet and ATM, and TDM was
   defined to cover both SONET/SDH [RFC4606] and G.709 [RFC4328]. The
   basic assumption was that different technologies of the same type
   would never operate within the same control, i.e., signaling and
   routing, domains.

   The past approach in assignment of Switching Types has proven to be



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   problematic from two perspectives.  The first issue is that some
   examples of switching technologies have different levels of switching
   that can be performed within the same technology.  For example, there
   are multiple types of Ethernet switching that may occur within a
   provider network.  The second issues is that the Switching Capability
   field value is used in Interior Gateway Protocols (IGPs) to indicate
   the format of the Switching Capability-specific information (SCSI)
   field, and that an implicit mapping of type to SCSI format is
   impractical for implementations that support multiple switching
   technologies.  These issues led to the introduction of two new types
   for Ethernet in [RFC6004] and [RFC6060], namely:
      7. Ethernet Virtual Private Line (EVPL)
      8. 802_1 PBB-TE (Provider Backbone Bridge - Traffic Engineering)

   An additional value is also envisioned to be assigned in support of
   G.709v3 by [GMPLS-G709] in order to disambiguate the format of the
   SCSI field.

   While a common representation of hierarchy levels within a switching
   technology certainly fits the design objectives of GMPLS, the
   definition of multiple PSC Switching Types has also proven to be of
   little value.  Notably, there are no known uses of PSC-2, PSC-3 and
   PSC-4.

   This document proposes to resolve such inconsistent definitions and
   uses of the Switching Types by reducing the scope of the related
   fields and narrowing their use.  In particular this document proposes
   deprecating the use of the Switching Types as an identifier of
   hierarchy levels within a switching technology, and limit its use to
   identification of a per-switching technology SCSI field format.

   This document updates any document that uses the GMPLS Switching
   Capability and Switching Type fields, in particular RFCs 3471, 4202,
   4203, and 5307.


1.1. Current Switching Type Definition

   The Switching Type values are carried in both routing and signaling
   protocols.  Values are identified in the IANA GMPLS Signaling
   Parameters Switching Type registry, which is currently located at
      http://www.iana.org/assignments/gmpls-sig-parameters/gmpls-sig-
      parameters.xml

   For routing, a common information element is defined to carry
   switching type values for both OSPF and IS-IS routing protocols in
   [RFC4202].  Per [RFC4202], switching type values are carried in a
   Switching Capability (Switching Cap) field in an Interface Switching
   Capability Descriptor.  This information shares a common formatting
   in both OSPF, as defined by [RFC4203], and in IS-IS, as defined by
   [RFC5307]:



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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Switching Cap |   Encoding    |           Reserved            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                     ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Switching Capability-specific information              |
      |                  (variable)                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   and

      The content of the Switching Capability-specific information field
      depends on the value of the Switching Capability field.

   Similarly, the Switching Type field is defined as part of a common
   format for use by GMPLS signaling protocols in [RFC3471] and is used
   by [RFC3473]:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | LSP Enc. Type |Switching Type |             G-PID             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Switching Type: 8 bits

         Indicates the type of switching that should be performed on a
         particular link.  This field is needed for links that advertise
         more than one type of switching capability.  This field should
         map to one of the values advertised for the corresponding link
         in the routing Switching Capability Descriptor ...


1.2. 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 [RFC2119].


2. Revised Switching Type Definition

   This document modifies the definition of Switching Type.  The
   definitions are slightly different for routing and signaling and are
   described in the following sections.







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2.1. Routing -- Switching Cap Field

   For routing, i.e., [RFC4202], [RFC4203], and [RFC5307], the following
   definition should be used for Switching Cap field:

      The Switching Cap field indicates the type of switching being
      advertised via GMPLS Switching Type values.  A different Switching
      Type value SHOULD be used for each data plane technology even when
      those technologies share the same type of multiplexing or
      switching.  For example, Time Division Multiplexing (TDM)
      technologies that have different multiplexing structures, such as
      SDH [G.707] and OTN [G.709], should use two different Switching
      Types.

      As the format of the Switching Capability-specific information
      field is dependent on the value of this field, a different
      Switching Type value MUST be used to differentiate between
      different Switching Capability-specific information field formats.

      This definition does not modify the format of the Interface
      Switching Capability Descriptor.

   Note that from a practical standpoint, this means that any time a new
   switching technology might use a different Switching Capability-
   specific information field format, that a new Switching Type SHOULD
   be used.


2.2. Signaling -- Switching Type Field

   For signaling, i.e., [RFC3471] which is used by [RFC3473], the
   following definition should be used for Switching Type field:

      Indicates the type of switching that should be performed on a
      particular link via GMPLS Switching Type values.  This field maps
      to one of the values advertised for the corresponding link in the
      routing Switching Capability Descriptor, see [RFC4203] and
      [RFC5307].

   Note that from a practical standpoint, there is no change in the
   definition of this field.


2.3. Assigned Switching Types

   This document deprecates the following Switching Types:

       Value                  Name
         2    Packet-Switch Capable-2 (PSC-2)
         3    Packet-Switch Capable-3 (PSC-3)
         4    Packet-Switch Capable-4 (PSC-4)



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      These values SHOULD be treated as unsupported types and, in the
      case of signaling, processed according to Section 2.1.1 of
      [RFC3473].


3. Compatibility

   For existing implementations, the primary impact of this document is
   deprecating the use of PSC-2, 3 and 4.  At the time of publication,
   there are no known deployments (or even implementations) that make
   use of these values so there is no compatibility issues for current
   routing and signaling implementations.


4. Security Considerations

   This document impacts the values carried in a single field in
   signaling and routing.  As no new protocol formats or mechanisms are
   defined, there are no particular security implications raised by this
   document.

   For a general discussion on MPLS and GMPLS related security issues,
   see the MPLS/GMPLS security framework [RFC5920].


5. IANA Considerations

   IANA needs to deprecate and redefine the related registry. In
   particular the Switching Types portion of the Generalized Multi-
   Protocol Label Switching (GMPLS) Signaling Parameters should be
   revised to read:

      Switching Types

         Registration Procedures

       Standards Action

         Reference
                 [RFC3471][RFC4328][This.draft]

          Value                  Name                  Reference
            0    Unassigned
            1    Packet-Switch Capable-1 (PSC-1)       [RFC3471]
            2    Deprecated                            [This.draft]
            3    Deprecated                            [This.draft]
            4    Deprecated                            [This.draft]
          5-29   Unassigned
           30    Ethernet Virtual Private Line (EVPL)  [RFC6004]
          31-39  Unassigned
           40    802_1 PBB-TE                          [RFC6060]



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          41-50  Unassigned
           51    Layer-2 Switch Capable (L2SC)         [RFC3471]
          52-99  Unassigned
           100   Time-Division-Multiplex Capable (TDM) [RFC3471]
         101-124 Unassigned
           125   Data Channel Switching Capable (DCSC) [RFC6002]
         126-149 Unassigned
           150   Lambda-Switch Capable (LSC)           [RFC3471]
         151-199 Unassigned
           200   Fiber-Switch Capable (FSC)            [RFC3471]
         201-255 Unassigned

   A parallel change to IANA-GMPLS-TC-MIB is also required. In
   particular, under IANAGmplsSwitchingTypeTC a reference to this
   document should be added as item 3. Also the following changes should
   be made to the related values:

          psc2(2),      -- Deprecated [This.draft]
          psc3(3),      -- Deprecated [This.draft]
          psc4(4),      -- Deprecated [This.draft]



6. Acknowledgments

   We thank John Drake for highlighting the current inconsistent
   definitions associated with the Switching Capability and Type Fields.
   Daniele Ceccarelli and Adrian Farrel provided valuable feedback on
   this document.


7. References

7.1. Normative References

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

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Functional Description", RFC 3471,
             January 2003.

   [RFC4202] Kompella, K., Rekhter, Y., "Routing Extensions in
             Support of Generalized Multi-Protocol Label Switching
             (GMPLS)", RFC 4202, October 2005.

   [RFC4203] Kompella, K., Rekhter, Y., "OSPF Extensions in Support
             of Generalized Multi-Protocol Label Switching (GMPLS)",
             RFC 4203, October 2005.





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   [RFC5307] Kompella, K., Rekhter, Y., "IS-IS Extensions in Support
             of Generalized Multi-Protocol Label Switching (GMPLS)",
             RFC 5307, October 2008.


7.2. Informative References

   [G.707] ITU-T Recommendation G.707/Y.1322 (2007), "Network node
           interface for the synchronous digital hierarchy (SDH)".

   [G.709] ITU-T Recommendation G.709/Y.1331 (2009), "Interfaces for
           the Optical Transport Network (OTN)".

   [GMPLS-G709] Zhang, F., Li, D., Li, H., Belotti, S., Ceccarelli,
                D., "Framework for GMPLS and PCE Control of G.709
                Optical Transport Networks", work in progress,
                draft-ietf-ccamp-gmpls-g709-framework.

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

   [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
             (GMPLS) Architecture", RFC 3945, October 2004.

   [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Extensions for G.709 Optical
             Transport Networks Control", RFC 4328, January 2006.

   [RFC4606] Mannie, E., Papadimitriou, D., "Generalized
             Multi-Protocol Label Switching (GMPLS) Extensions for
             Synchronous Optical Network (SONET) and Synchronous
             Digital Hierarchy (SDH) Control", RFC 4606, August 2006.

   [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
             Networks", RFC 5920, July 2010.

   [RFC6002] Berger, L., Fedyk, D., "Generalized MPLS (GMPLS) Data
             Channel Switching Capable (DCSC) and Channel Set Label
             Extensions", RFC 6002, October 2010.

   [RFC6004] Berger, L., Fedyk, D., "Generalized MPLS (GMPLS) Support
             for Metro Ethernet Forum and G.8011 Ethernet Service
             Switching", RFC 6004, front 2010.

   [RFC6060] Fedyk, D., Shah, H., Bitar, N., Takacs, A., "Generalized
             Multiprotocol Label Switching (GMPLS) Control of
             Ethernet Provider Backbone Traffic Engineering
             (PBB-TE)", RFC 6060, March 2011.




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8. Authors' Addresses

   Lou Berger
   LabN Consulting, L.L.C.
   Phone: +1 301 468 9228
   Email: lberger@labn.net

   Julien Meuric
   France Telecom Orange
   Research & Development
   2, Avenue Pierre Marzin
   22307 Lannion Cedex - France
   Phone: +33 2 96 05 28 28
   Email: julien.meuric@orange.com








































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