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draft-ietf-teas-gmpls-scsi.xml
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draft-ietf-teas-gmpls-scsi.xml
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="6"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc compact="yes" ?>
<?rfc subcompact="no" ?>
<rfc ipr="trust200902" category="std" docName="draft-ietf-teas-gmpls-scsi-04">
<front>
<title abbrev="Generalized SCSI">
Generalized Interface Switching Capability
Descriptor - Switching Capability Specific Information
</title>
<author initials="D." surname="Ceccarelli" fullname="Daniele Ceccarelli">
<organization>Ericsson</organization>
<address>
<postal>
<street>Torshamnsgatan 21</street>
<code></code>
<city>Kista - Stockholm</city>
<country>Sweden</country>
</postal>
<email>daniele.ceccarelli@ericsson.com</email>
</address>
</author>
<author initials='L.' surname="Berger" fullname='Lou Berger'>
<organization>LabN Consulting, L.L.C.</organization>
<address> <email>lberger@labn.net</email>
</address>
</author>
<date year="2017" />
<area>Routing</area>
<workgroup>TEAS Working Group</workgroup>
<keyword>OSPF-TE</keyword>
<keyword>GMPLS</keyword>
<abstract>
<t>
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 associate protocol standards.
</t>
</abstract>
</front>
<middle>
<section title="Introduction" anchor="sec-intro">
<t>
The context for this document is Generalized MPLS, and the
reader is expected to be familiar with the GMPLS architecture,
associate terminology and protocol standards. Notably, but
not limited to, <xref target="RFC3945"/>, <xref
target="RFC4202"/>, <xref target="RFC4203"/> and <xref
target="RFC5307"/>.
</t>
<t>
The Interface Switching Capability Descriptor (ISCD) <xref
target="RFC4202"/> allows routing protocols such as OSPF and
ISIS to carry technology specific information in the the
Switching Capability-specific information (SCSI) field, see
<xref target="RFC4203"/> and <xref target="RFC5307"/>. The
format of an SCSI field is dictated by the specific technology
being represented as indicated by the ISCD Switching Capability
(SC) type field. Existing Switching Capabilities are managed by
IANA in the <eref
target="http://www.iana.org/assignments/gmpls-sig-parameters/gmpls-sig-parameters.xml#gmpls-sig-parameters-3">Switching
Types registry</eref> and the related "IANA-GMPLS-TC-MIB"
definitions.
</t>
<t>
<xref target="RFC7138"/> introduced a "sub-TLV" structure to its
technology specific SCSI field. The Sub-Type-Length-Value (TLV)
based approach allows for greater flexibility in the structure,
ordering, and ability to support extensions of the SC
(technology) specific format. This Sub-TLV approach is also
used in <xref target="RFC7688"/>.
</t>
<t>
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., <xref
target="I-D.ietf-ccamp-ospf-availability-extension"/>). This
document also establishes a registry for SCSI-TLV definitions
that may be shared across multiple technologies.
</t>
</section>
<section title="Terminology" anchor="sec-definitions">
<t>
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 <xref target="RFC2119"/>.
</t>
<t>
The reader is expected to be familiar with GMPLS terminology,
e.g. as found in <xref target="RFC3945"/>, as well as the
terminology used in <xref target="RFC4202"/>, <xref
target="RFC4203"/> and <xref target="RFC5307"/>.
</t>
</section>
<!--2-->
<section title="Generalized SCSI Formats" anchor="sec-format">
<t>
The Generalized SCSI is composed of zero or more variable length
type-length-value fields which are each called a SCSI-TLV.
There are no specific size restrictions on these SCSI-TLV. Size
and other formatting restrictions may be imposed by the routing
protocol ISCD field, refer to <xref target="RFC4203"/> and <xref
target="RFC5307"/>. Please also refer to <xref target="RFC3630"/> for
the treatment of malformed Link TLVs.
</t>
<t>
<figure title="TLV format" anchor="fig-a">
<preamble>The SCSI-TLV format is:</preamble>
<artwork>
<![CDATA[
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 ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]>
</artwork>
<postamble></postamble>
</figure>
<list style="hanging">
<t hangText="Type (2 octets):"><vspace blankLines="0" />
This field indicates the type and structure of the information
contained in the Value field.
</t>
<t hangText="Length (2 octets):"><vspace blankLines="0" />
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.
</t>
<t hangText="Value (variable):"><vspace blankLines="0" />
A variable length field, formatted according to the definition
indicated by value of the Type field. This field can be
omitted for certain types.
</t>
</list>
</t>
</section>
<section title="Procedures" anchor="sec-proc">
<t>
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.
</t> <t>
The Generalized SCSI MAY contain a sequence of zero or more
SCSI-TLVs. Sub-TLV parsing (format) errors, such as an underrun
or overrun, 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.
</t>
</section>
<!--4-->
<section title="Security Considerations" anchor="sec-secu">
<t>
This document does not introduce any security issue beyond those
discussed in <xref target="RFC4203"/> and <xref
target="RFC5307"/>. As discussed there, the information carried
in ISCDs are not used for SPF computation or normal routing and
the extensions here defined do not have direct effect on IP
routing. Tampering with GMPLS TE LSAs may have an effect on the
underlying transport network. Mechanisms such as <xref
target="RFC2154"/> and <xref target="RFC5304"/> to protect the
transmission of this information are suggested.
</t>
</section>
<!--5-->
<section title="IANA Considerations" anchor="sec-iana">
<t>
This document defines a new SCSI-TLV that is carried in the SCSI
field of the ISCDs defined in <xref target="RFC4203"/> and <xref
target="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.
</t>
<t>
IANA is requested to create and maintain a new registry, the
"Generalized SCSI (Switching Capability Specific Information)
TLVs Types" registry under the the "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Parameters"
registry.
</t>
<t>
The definition of the new registry is as follows:
</t>
<t>
<figure>
<artwork>
<![CDATA[
Value SCSI-TLV Switching Type Reference
--------- ----------------------- -------------- ---------
0 Reserved [This ID]
1-65535 Unassigned (value list) [This ID]
]]>
</artwork>
</figure>
New allocation requests to this registry must indicate the
value or values to be used in the Switching Type column.
</t>
<t>
The registry should be established with registration policies of
"Specification Required", see <xref
target="RFC5226"/>. </t>
<t>
REMOVE THIS AFTER PUBLICATION: The designated expert will be
appointed by the Routing AD. It is suggested to appoint any
current TEAS WG chair.
</t>
</section>
<section title="Acknowledgments" anchor="sec-ack">
<t>
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.
</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.RFC.3630"?>
<?rfc include="reference.RFC.4202"?>
<?rfc include="reference.RFC.4203"?>
<?rfc include="reference.RFC.5307"?>
</references>
<references title="Informative References">
<?rfc include="reference.I-D.ietf-ccamp-ospf-availability-extension.xml"?>
<?rfc include="reference.RFC.2154"?>
<?rfc include="reference.RFC.3945"?>
<?rfc include="reference.RFC.5304"?>
<?rfc include="reference.RFC.5226"?>
<?rfc include="reference.RFC.7138"?>
<?rfc include="reference.RFC.7688"?>
</references>
</back>
</rfc>
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