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Internet Engineering Task Force (IETF)                     D. CeccarelliRequest for Comments: 8258                                      EricssonCategory: Standards Track                                      L. BergerISSN: 2070-1721                                  LabN Consulting, L.L.C.                                                            October 2017Generalized SCSI: A Generic Structurefor 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 inSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc8258.Ceccarelli & Berger          Standards Track                    [Page 1]

RFC 8258                    Generalized SCSI                October 2017Copyright Notice   Copyright (c) 2017 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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 Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .22.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .33.  Generalized SCSI Formats  . . . . . . . . . . . . . . . . . .34.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .45.  Security Considerations . . . . . . . . . . . . . . . . . . .46.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .57.  References  . . . . . . . . . . . . . . . . . . . . . . . . .57.1.  Normative References  . . . . . . . . . . . . . . . . . .57.2.  Informative References  . . . . . . . . . . . . . . . . .6   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .7   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .71.  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 inBCP 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 FormatCeccarelli & 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 20176.  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.  References7.1.  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 inRFC2119 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.netCeccarelli & Berger          Standards Track                    [Page 7]