





Internet Engineering Task Force (IETF)                           H. Long
Request for Comments: 8330                                         M. Ye
Category: Standards Track                  Huawei Technologies Co., Ltd.
ISSN: 2070-1721                                                G. Mirsky
                                                                     ZTE
                                                         A. D'Alessandro
                                                   Telecom Italia S.p.A.
                                                                 H. Shah
                                                                   Ciena
                                                           February 2018


     OSPF Traffic Engineering (OSPF-TE) Link Availability Extension
               for Links with Variable Discrete Bandwidth

Abstract

   A network may contain links with variable discrete bandwidth, e.g.,
   microwave and copper.  The bandwidth of such links may change
   discretely in response to a changing external environment.  The word
   "availability" is typically used to describe such links during
   network planning.  This document defines a new type of Generalized
   Switching Capability-Specific Information (SCSI) TLV to extend the
   Generalized Multiprotocol Label Switching (GMPLS) Open Shortest Path
   First (OSPF) routing protocol.  The extension can be used for route
   computation in a network that contains links with variable discrete
   bandwidth.  Note that this document only covers the mechanisms by
   which the availability information is distributed.  The mechanisms by
   which availability information of a link is determined and the use of
   the distributed information for route computation are outside the
   scope of this document.  It is intended that technology-specific
   documents will reference this document to describe specific uses.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8330.





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Copyright Notice

   Copyright (c) 2018 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
   (https://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. Conventions Used in This Document ..........................3
   2. Abbreviations ...................................................4
   3. Overview ........................................................4
   4. TE Metric Extension to OSPF-TE ..................................5
      4.1. Availability SCSI-TLV ......................................5
      4.2. Processing Procedures ......................................6
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................7
   7. References ......................................................7
      7.1. Normative References .......................................7
      7.2. Informative References .....................................8
   Acknowledgments ...................................................10
   Authors' Addresses ................................................10




















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1.  Introduction

   Some data-plane technologies, e.g., microwave and copper, allow
   seamless changes of maximum physical bandwidth through a set of known
   discrete values.  The parameter "availability", as described in
   [G.827], [F.1703], and [P.530], is often used to describe the link
   capacity.  The availability is a time scale, representing a
   proportion of the operating time that the requested bandwidth is
   ensured.  To set up a Label Switched Path (LSP) across these links,
   availability information is required by the nodes to verify the
   bandwidth before making a bandwidth reservation.  Assigning different
   availability classes over such links provides for more efficient
   planning of link capacity to support different types of services.
   The link availability information will be determined by the operator
   and is statically configured.  It will usually be determined from the
   availability requirements of the services expected to be carried on
   the LSP.  For example, voice service usually needs "five nines"
   availability, while non-real-time services may adequately perform at
   four or three nines availability.  For the route computation, both
   the availability information and the bandwidth resource information
   are needed.  Since different service types may need different
   availability guarantees, multiple <availability, bandwidth> pairs may
   be required to be associated with a link.

   In this document, a new type of Generalized SCSI-TLV, the
   Availability SCSI-TLV, is defined.  It is intended that technology-
   specific documents will reference this document to describe specific
   uses.  The signaling extension to support links with variable
   discrete bandwidth is defined in [RSVP-TE-Availability].

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.














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2.  Abbreviations

   The following abbreviations are used in this document:

   GMPLS     Generalized Multiprotocol Label Switching

   ISCD      Interface Switching Capability Descriptor

   LSA       Link State Advertisement

   LSP       Label Switched Path

   OSPF      Open Shortest Path First

   SCSI      Switching Capability-Specific Information

   SPF       Shortest Path First

   TE        Traffic Engineering

   TLV       Type-Length-Value

3.  Overview

   A node that has link(s) with variable discrete bandwidth attached
   should include an <availability, bandwidth> information list in its
   OSPF-TE LSA messages.  The list provides the mapping between the link
   nominal bandwidth and its availability level.  This information is
   used for path calculation by the node(s).  The setup of an LSP
   requires this information to be flooded in the network and used by
   the nodes or the PCE for the path computation.  In this document, a
   new type of Generalized SCSI-TLV, the Availability SCSI-TLV, is
   defined.  The computed path can then be provisioned via the signaling
   protocol [RSVP-TE-Availability].

   Note: The mechanisms described in this document only distribute
   availability information.  The methods for measuring the information
   or using the information for route computation are outside the scope
   of this document.












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4.  TE Metric Extension to OSPF-TE

4.1.  Availability SCSI-TLV

   The Generalized SCSI is defined in [RFC8258].  This document defines
   a new type of Generalized SCSI-TLV called the Availability SCSI-TLV.
   The Availability SCSI-TLV can be included one or more times.  It has
   the following format:

      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          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   Availability level                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                   LSP Bandwidth at Availability level n       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: 0x000A, 16 bits

      Length: 2 octets (16 bits)

      Availability level: 32 bits

         This field is a binary32-format floating-point number as
         defined by [IEEE754-2008].  The bytes are transmitted in
         network order; that is, the byte containing the sign bit is
         transmitted first.  This field describes the decimal value of
         the availability guarantee of the Switching Capability in the
         Interface Switching Capability Descriptor object [RFC4202].
         The value MUST be less than 1.  The Availability level field is
         usually expressed as the value 0.99/0.999/0.9999/0.99999.

      LSP Bandwidth at Availability level n: 32 bits

         This field is a 32-bit IEEE floating-point number as defined by
         [IEEE754-2008].  The bytes are transmitted in network order;
         that is, the byte containing the sign bit is transmitted first.
         This field describes the LSP bandwidth for the availability
         level represented in the Availability level field.  The units
         are bytes per second.









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4.2.  Processing Procedures

   The ISCD allows routing protocols such as OSPF to carry technology-
   specific information in the "Switching Capability-specific
   information" field; see [RFC4203].  A node advertising an interface
   with a Switching Capability that supports variable discrete bandwidth
   attached SHOULD contain one or more Availability SCSI-TLVs in its
   OSPF-TE LSA messages.  Each Availability SCSI-TLV provides
   information about how much bandwidth a link can support for a
   specified availability.  This information may be used for path
   calculation by the node(s).

   The Availability SCSI-TLV MUST NOT be sent in ISCDs with Switching
   Capability field values that have not been defined to support the
   Availability SCSI-TLV.  Non-supporting nodes would see such an
   ISCD/LSA as malformed.

   The absence of the Availability SCSI-TLV in an ISCD containing
   Switching Capability field values that have been defined to support
   the Availability SCSI-TLV SHALL be interpreted as representing the
   fixed-bandwidth link with the highest availability value.

   Only one Availability SCSI-TLV for the specific availability level
   SHOULD be sent.  If multiple TLVs are present, the Availability
   SCSI-TLV with the lowest bandwidth value SHALL be processed.  If an
   Availability SCSI-TLV with an invalid value (e.g., larger than 1) is
   received, the Availability SCSI-TLV will be ignored.

5.  Security Considerations

   This document specifies the contents of Opaque LSAs in OSPFv2.
   Tampering with GMPLS-TE LSAs may have an effect on TE computations.
   [RFC3630] suggests such mechanisms as the mechanism described in
   [RFC2154] to protect the transmission of this information, and those
   or other mechanisms should be used to secure and/or authenticate the
   information carried in the Opaque LSAs.  An analysis of the security
   of OSPF is provided in [RFC6863] and applies to the OSPF extension
   defined in this document.  Any new mechanisms developed to protect
   the transmission of information carried in Opaque LSAs will also
   automatically protect the extension defined in this document.

   Please refer to [RFC5920] for details on security threats; defensive
   techniques; monitoring, detection, and reporting of security attacks;
   and requirements.







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6.  IANA Considerations

   This document introduces a new type of Generalized SCSI-TLV
   (Availability) that is carried in the OSPF-TE LSA messages.
   Technology-specific documents will reference this document to
   describe the specific use of this Availability SCSI-TLV.

   IANA created a registry called the "Generalized SCSI (Switching
   Capability Specific Information) TLV Types" registry [RFC8258].  The
   registry has been updated to include the following Availability
   SCSI-TLV:

      Type     Description    Switching Type   Reference
      ------   ------------   --------------   ---------
      0x000A   Availability   5, 52            RFC 8330

   New switching types are required in order to use the Availability
   SCSI-TLV.  IANA has registered the following in the "Switching Types"
   registry:

     Value  Name                       Reference
     -----  -------------------------- ---------
         5  PSC with GSCSI support     RFC 8330
        52  L2SC with GSCSI support    RFC 8330

7.  References

7.1.  Normative References

   [IEEE754-2008]
              IEEE, "IEEE Standard for Floating-Point Arithmetic",
              IEEE 754-2008, DOI 10.1109/IEEESTD.2008.4610935.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4202]  Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
              Extensions in Support of Generalized Multi-Protocol Label
              Switching (GMPLS)", RFC 4202, DOI 10.17487/RFC4202,
              October 2005, <https://www.rfc-editor.org/info/rfc4202>.

   [RFC4203]  Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
              in Support of Generalized Multi-Protocol Label Switching
              (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
              <https://www.rfc-editor.org/info/rfc4203>.




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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in
              RFC 2119 Key Words", BCP 14, RFC 8174,
              DOI 10.17487/RFC8174, May 2017,
              <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8258]  Ceccarelli, D. and L. Berger, "Generalized SCSI: A Generic
              Structure for Interface Switching Capability Descriptor
              (ISCD) Switching Capability Specific Information (SCSI)",
              RFC 8258, DOI 10.17487/RFC8258, October 2017,
              <https://www.rfc-editor.org/info/rfc8258>.

7.2.  Informative References

   [F.1703]   International Telecommunication Union, "Availability
              objectives for real digital fixed wireless links used in
              27 500 km hypothetical reference paths and connections",
              ITU-R Recommendation F.1703-0, January 2005,
              <https://www.itu.int/rec/R-REC-F.1703-0-200501-I/en>.

   [G.827]    International Telecommunication Union, "Availability
              performance parameters and objectives for end-to-end
              international constant bit-rate digital paths", ITU-T
              Recommendation G.827, September 2003,
              <https://www.itu.int/rec/T-REC-G.827/en>.

   [P.530]    International Telecommunication Union, "Propagation data
              and prediction methods required for the design of
              terrestrial line-of-sight systems", ITU-R
              Recommendation P.530-17, December 2017,
              <https://www.itu.int/rec/R-REC-P.530/en>.

   [RFC2154]  Murphy, S., Badger, M., and B. Wellington, "OSPF with
              Digital Signatures", RFC 2154, DOI 10.17487/RFC2154,
              June 1997, <https://www.rfc-editor.org/info/rfc2154>.

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              DOI 10.17487/RFC3630, September 2003,
              <https://www.rfc-editor.org/info/rfc3630>.

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
              <https://www.rfc-editor.org/info/rfc5920>.








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   [RFC6863]  Hartman, S. and D. Zhang, "Analysis of OSPF Security
              According to the Keying and Authentication for Routing
              Protocols (KARP) Design Guide", RFC 6863,
              DOI 10.17487/RFC6863, March 2013,
              <https://www.rfc-editor.org/info/rfc6863>.

   [RSVP-TE-Availability]
              Long, H., Ye, M., Mirsky, G., D'Alessandro, A., and H.
              Shah, "Ethernet Traffic Parameters with Availability
              Information", Work in Progress, draft-ietf-ccamp-rsvp-te-
              bandwidth-availability-08, January 2018.








































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Acknowledgments

   The authors would like to thank Acee Lindem, Daniele Ceccarelli, and
   Lou Berger for their comments on the document.

Authors' Addresses

   Hao Long
   Huawei Technologies Co., Ltd.
   No. 1899, Xiyuan Avenue, Hi-tech Western District
   Chengdu  611731
   China

   Phone: +86-18615778750
   Email: longhao@huawei.com


   Min Ye
   Huawei Technologies Co., Ltd.
   No. 1899, Xiyuan Avenue, Hi-tech Western District
   Chengdu  611731
   China

   Email: amy.yemin@huawei.com


   Greg Mirsky
   ZTE

   Email: gregimirsky@gmail.com


   Alessandro D'Alessandro
   Telecom Italia S.p.A.

   Email: alessandro.dalessandro@telecomitalia.it


   Himanshu Shah
   Ciena Corp.
   3939 North First Street
   San Jose, CA  95134
   United States of America

   Email: hshah@ciena.com






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