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rfc:rfc8258

Internet Engineering Task Force (IETF) D. Ceccarelli Request for Comments: 8258 Ericsson Category: Standards Track L. Berger ISSN: 2070-1721 LabN Consulting, L.L.C.

                                                          October 2017
               Generalized SCSI: A Generic Structure
        for Interface Switching Capability Descriptor (ISCD)
          Switching Capability Specific Information (SCSI)

Abstract

 This document defines a generic information structure for information
 carried in routing protocol Interface Switching Capability Descriptor
 (ISCD) Switching Capability Specific Information (SCSI) fields.  This
 "Generalized SCSI" can be used with routing protocols that define
 GMPLS ISCDs and any specific technology.  This document does not
 modify any existing technology-specific formats and is defined for
 use in conjunction with new GMPLS Switching Capability types.  The
 context for this document is Generalized MPLS, and the reader is
 expected to be familiar with the GMPLS architecture and associated
 protocol standards.

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/rfc8258.

Ceccarelli & Berger Standards Track [Page 1] RFC 8258 Generalized SCSI October 2017

Copyright Notice

 Copyright (c) 2017 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
 3.  Generalized SCSI Formats  . . . . . . . . . . . . . . . . . .   3
 4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   4
 5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
   7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   7
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1. Introduction

 The context for this document is Generalized MPLS, and the reader is
 expected to be familiar with the GMPLS architecture, associated
 terminology, and protocol standards: notably, but not limited to,
 [RFC3945], [RFC4202], [RFC4203] and [RFC5307].
 The Interface Switching Capability Descriptor (ISCD) [RFC4202] allows
 routing protocols such as OSPF and ISIS to carry technology-specific
 information in the Switching Capability-specific information field,
 see [RFC4203] and [RFC5307].  The format of an SCSI field is dictated
 by the specific technology being represented as indicated by the ISCD
 Switching Capability field.  Existing Switching Capabilities are
 managed by IANA in the "Switching Types" registry
 <http://www.iana.org/assignments/gmpls-sig-parameters> and the
 related "IANA-GMPLS-TC-MIB" definitions.

Ceccarelli & Berger Standards Track [Page 2] RFC 8258 Generalized SCSI October 2017

 [RFC7138] introduced a "sub-TLV" structure to its technology-specific
 SCSI field.  The sub-TLV-based approach allows for greater
 flexibility in the structure, ordering, and ability to support
 extensions of the SC-specific format.  This Sub-TLV approach is also
 used in [RFC7688].
 This document generalizes this approach and defines a new generalized
 SCSI field format for use by future specific technologies and
 Switching Capability types.  The generalized SCSI carries SCSI-TLVs
 that may be defined within the scope of a specific technology or
 shared across multiple technologies (e.g., [AVAIL-EXT]).  This
 document also establishes a registry for SCSI-TLV definitions that
 may be shared across multiple technologies.

2. Terminology

 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.
 The reader is expected to be familiar with GMPLS terminology (e.g.,
 as found in [RFC3945]) as well as the terminology used in [RFC4202],
 [RFC4203], and [RFC5307].

3. Generalized SCSI Formats

 The Generalized SCSI is composed of zero or more variable-length TLV
 fields each of which is called an "SCSI-TLV".  There are no specific
 size restrictions on these SCSI-TLVs.  Size and other formatting
 restrictions may be imposed by the routing protocol ISCD field (refer
 to [RFC4203] and [RFC5307]).  Please refer to [RFC3630] for the
 treatment of malformed Link TLVs.
 The SCSI-TLV format is:
     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            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...                           Value                           ...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                         Figure 1: TLV Format

Ceccarelli & Berger Standards Track [Page 3] RFC 8258 Generalized SCSI October 2017

 Type (2 octets):
    This field indicates the type and structure of the information
    contained in the Value field.
 Length (2 octets):
    This field MUST be set to the size, in octets (bytes), of the
    Value field.  The value of the field MUST be zero or divisible by
    4.  Note that this implies that the Value field can be omitted or
    contain padding.
 Value (variable):
    A variable-length field, formatted according to the definition
    indicated by value of the Type field.  This field can be omitted
    for certain types.

4. Procedures

 The ISCD can include a Generalized SCSI when advertising technologies
 whose Switching Capability definition references this document.  The
 corollary of this is that the Generalized SCSI MUST NOT be used for
 ISCDs of technologies whose Switching Capability definition do not
 reference this document.
 The Generalized SCSI MAY contain a sequence of zero or more SCSI-
 TLVs.  Sub-TLV parsing (format) errors MUST be treated as a malformed
 ISCD.  SCSI-TLVs MUST be processed in the order received and, if re-
 originated, ordering MUST be preserved.  Unknown SCSI-TLVs MUST be
 ignored and transparently processed, i.e., re-originated when
 appropriate.  Processing related to multiple SCSI-TLVs of the same
 type may be further refined based on the definition on the type.

5. Security Considerations

 This document does not introduce any security issue beyond those
 discussed in [RFC4203] and [RFC5307].  As discussed there, the
 information carried in ISCDs is not used for Shortest Path First
 (SPF) computation or normal routing, and the extensions here defined
 do not have a direct effect on IP routing.  Tampering with GMPLS
 Traffic Engineering (TE) Link State Advertisements (LSAs) may have an
 effect on the underlying transport network.  Mechanisms such as those
 described in [RFC2154] and [RFC5304] to protect the transmission of
 this information are suggested.

Ceccarelli & Berger Standards Track [Page 4] RFC 8258 Generalized SCSI October 2017

6. IANA Considerations

 This document defines a new SCSI-TLV that is carried in the SCSI
 field of the ISCDs defined in [RFC4203] and [RFC5307].  The SCSI-TLV
 includes a 16-bit type identifier (the Type field).  The same Type
 field values are applicable to the new SCSI-TLV.
 IANA has created and will maintain a new registry, the "Generalized
 SCSI (Switching Capability Specific Information) TLV Types" registry
 under the "Generalized Multi-Protocol Label Switching (GMPLS)
 Signaling Parameters" registry.
 The initial contents of this registry are as follows:
     Value       SCSI-TLV                Switching Type   Reference
     ---------   ----------------------- --------------   ---------
     0           Reserved                                 [RFC8258]
     1-65535     Unassigned              (value list)
 New allocation requests to this registry must indicate the value or
 values to be used in the Switching Type column.
 The registry should be established with registration policies of
 "Specification Required", see [RFC8126].

7. References

7.1. Normative References

 [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>.
 [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>.
 [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>.

Ceccarelli & Berger Standards Track [Page 5] RFC 8258 Generalized SCSI October 2017

 [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>.
 [RFC5307]  Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
            in Support of Generalized Multi-Protocol Label Switching
            (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
            <https://www.rfc-editor.org/info/rfc5307>.
 [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>.

7.2. Informative References

 [AVAIL-EXT]
            Long, H., Ye, M., Mirsky, G., D'Alessandro, A., and H.
            Shah, "OSPF-TE Link Availability Extension for Links with
            Variable Discrete Bandwidth", Work in Progress,
            draft-ietf-ccamp-ospf-availability-extension-10,
            August 2017.
 [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>.
 [RFC3945]  Mannie, E., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Architecture", RFC 3945,
            DOI 10.17487/RFC3945, October 2004,
            <https://www.rfc-editor.org/info/rfc3945>.
 [RFC5304]  Li, T. and R. Atkinson, "IS-IS Cryptographic
            Authentication", RFC 5304, DOI 10.17487/RFC5304, October
            2008, <https://www.rfc-editor.org/info/rfc5304>.
 [RFC7138]  Ceccarelli, D., Ed., Zhang, F., Belotti, S., Rao, R., and
            J. Drake, "Traffic Engineering Extensions to OSPF for
            GMPLS Control of Evolving G.709 Optical Transport
            Networks", RFC 7138, DOI 10.17487/RFC7138, March 2014,
            <https://www.rfc-editor.org/info/rfc7138>.
 [RFC7688]  Lee, Y., Ed. and G. Bernstein, Ed., "GMPLS OSPF
            Enhancement for Signal and Network Element Compatibility
            for Wavelength Switched Optical Networks", RFC 7688,
            DOI 10.17487/RFC7688, November 2015,
            <https://www.rfc-editor.org/info/rfc7688>.

Ceccarelli & Berger Standards Track [Page 6] RFC 8258 Generalized SCSI October 2017

 [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
            Writing an IANA Considerations Section in RFCs", BCP 26,
            RFC 8126, DOI 10.17487/RFC8126, June 2017,
            <https://www.rfc-editor.org/info/rfc8126>.

Acknowledgments

 The authors would like to thank Adrian Farrel and Julien Meuric for
 the careful review and suggestions.  Thomas Heide Clausen provided
 useful comments as part of the Routing Directorate review.

Authors' Addresses

 Daniele Ceccarelli
 Ericsson
 Torshamnsgatan 21
 Kista - Stockholm
 Sweden
 Email: daniele.ceccarelli@ericsson.com
 Lou Berger
 LabN Consulting, L.L.C.
 Email: lberger@labn.net

Ceccarelli & Berger Standards Track [Page 7]

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