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Internet Engineering Task Force (IETF)                       L. GinsbergRequest for Comments: 7370                                 Cisco SystemsCategory: Standards Track                                 September 2014ISSN: 2070-1721Updates to the IS-IS TLV Codepoints RegistryAbstract   This document recommends some editorial changes to the IANA "IS-IS   TLV Codepoints" registry to more accurately document the state of the   protocol.  It also sets out new guidelines for Designated Experts to   apply when reviewing allocations from the registry.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 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7370.Ginsberg                     Standards Track                    [Page 1]

RFC 7370                  IS-IS TLV Codepoints            September 2014Copyright Notice   Copyright (c) 2014 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   (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.   This document may contain material from IETF Documents or IETF   Contributions published or made publicly available before November   10, 2008.  The person(s) controlling the copyright in some of this   material may not have granted the IETF Trust the right to allow   modifications of such material outside the IETF Standards Process.   Without obtaining an adequate license from the person(s) controlling   the copyright in such materials, this document may not be modified   outside the IETF Standards Process, and derivative works of it may   not be created outside the IETF Standards Process, except to format   it for publication as an RFC or to translate it into languages other   than English.Ginsberg                     Standards Track                    [Page 2]

RFC 7370                  IS-IS TLV Codepoints            September 2014Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .31.1.  Requirements Language . . . . . . . . . . . . . . . . . .32.  IS Neighbor Sub-TLV Registry  . . . . . . . . . . . . . . . .43.  Prefix Reachability Sub-TLV Registry  . . . . . . . . . . . .44.  Guidance for Designated Experts . . . . . . . . . . . . . . .45.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .56.  Security Considerations . . . . . . . . . . . . . . . . . . .57.  References  . . . . . . . . . . . . . . . . . . . . . . . . .67.1.  Normative References  . . . . . . . . . . . . . . . . . .67.2.  Informative References  . . . . . . . . . . . . . . . . .6   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .7   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .71.  Introduction   The "IS-IS TLV Codepoints" registry was created by [RFC3563] and   extended by [RFC6233].  The assignment policy for the registry is   "Expert Review" as defined in [RFC5226].  As documents related to   IS-IS are developed, the codepoints required for the protocol   extensions are reviewed by the Designated Experts and added to the   IANA-managed registry.  As these documents are published as RFCs, the   registries are updated to reference the relevant RFC.   In the case of TLVs supporting prefix advertisement, currently   separate sub-TLV registries are maintained for each TLV.  These   registries need to be combined into a common sub-TLV registry similar   to what has been done for neighbor advertisement TLVs.   In some cases, there is a need to allocate codepoints defined in   Internet-Drafts (I-Ds) that seem likely to eventually gain Working   Group approval, without waiting for those I-Ds to be published as   RFCs.  This can be achieved using Expert Review, and this document   sets out guidance for the Designated Experts to apply when reviewing   allocations from the registry.1.1.  Requirements Language   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 inRFC 2119 [RFC2119].Ginsberg                     Standards Track                    [Page 3]

RFC 7370                  IS-IS TLV Codepoints            September 20142.  IS Neighbor Sub-TLV Registry   There was an existing common sub-TLV registry named "Sub-TLVs for   TLVs 22, 141, and 222".  [RFC5311] defines the IS Neighbor Attribute   TLV (23) and the MT IS Neighbor Attribute TLV (223).  The format of   these TLVs is identical to TLVs 22 and 222, respectively.  The IS   Neighbor sub-TLV registry has been extended to include these two   TLVs.  Settings for inclusion of each sub-TLV are identical to the   settings for TLVs 22 and 222, respectively.3.  Prefix Reachability Sub-TLV Registry   Previously, there existed separate sub-TLV registries for TLVs 135,   235, 236, and 237.  As in the case of the IS Neighbor TLVs discussed   in the previous section, assignment of sub-TLVs applicable to one or   more of these TLVs is intended to be common.  Therefore, the existing   separate sub-TLV registries have been combined into a single registry   entitled "Sub-TLVs for TLVs 135, 235, 236, and 237".  As existing   sub-TLV assignments are common to all the TLVs, this represents no   change to the protocol -- only a clearer representation of the   intended sub-TLV allocation strategy.  The format of the registry is   as shown below:   Type  Description                       135 235 236 237  Reference   ----  ------------                      --- --- --- ---  ---------   0     Unassigned   1     32-bit Administrative Tag Sub-TLV  y   y   y   y   [RFC5130]   2     64-bit Administrative Tag Sub-TLV  y   y   y   y   [RFC5130]   3-255 Unassigned4.  Guidance for Designated Experts   When new I-Ds are introduced requiring new codepoints, it is   advantageous to be able to allocate codepoints without waiting for   them to progress to RFC.  The reasons this is advantageous are   described in [RFC7120].  However, the procedures in [RFC7120] for   early allocation do not apply to registries, such as the "IS-IS TLV   Codepoints" registry, that utilize the "Expert Review" allocation   policy.  In such cases, what is required is that a request be made to   the Designated Experts who MAY approve the assignments according to   the guidance that has been established for the registry concerned.   The following guidance applies specifically to the "IS-IS TLV   Codepoints" registry.   1.  Application for a codepoint allocation MAY be made to the       Designated Experts at any time.Ginsberg                     Standards Track                    [Page 4]

RFC 7370                  IS-IS TLV Codepoints            September 2014   2.  The Designated Experts SHOULD only consider requests that arise       from I-Ds that have already been accepted as Working Group       documents or that are planned for progression as AD Sponsored       documents in the absence of a suitably chartered Working Group.   3.  In the case of Working Group documents, the Designated Experts       SHOULD check with the Working Group chairs that there is       consensus within the Working Group to make the allocation at this       time.  In the case of AD Sponsored documents, the Designated       Experts SHOULD check with the AD for approval to make the       allocation at this time.   4.  The Designated Experts SHOULD then review the assignment requests       on their technical merit.  The Designated Experts SHOULD NOT seek       to overrule IETF consensus, but they MAY raise issues for further       consideration before the assignments are made.   5.  Once the Designated Experts have granted approval, IANA will       update the registry by marking the allocated codepoints with a       reference to the associated document as normal.   6.  In the event that the document fails to progress to RFC, the       Expiry and deallocation process defined in [RFC7120] MUST be       followed for the relevant codepoints -- noting that the       Designated Experts perform the role assigned to Working Group       chairs.5.  IANA Considerations   This document provides guidance to the Designated Experts appointed   to manage allocation requests in the "IS-IS TLV Codepoints" registry.   IANA has updated the registry that was specified as "Sub-TLVs for   TLVs 22, 141, and 222" to be named "Sub-TLVs for TLVs 22, 23, 141,   222, and 223".   Per this document, the existing sub-TLV registries for TLVs 135, 235,   236, and 237 have been combined into a single registry -- the   "Sub-TLVs for TLVs 135, 235, 236, and 237" registry -- as described   inSection 3.6.  Security Considerations   This document introduces no new security issues.Ginsberg                     Standards Track                    [Page 5]

RFC 7370                  IS-IS TLV Codepoints            September 20147.  References7.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997,              <http://www.rfc-editor.org/info/rfc2119>.   [RFC5130]  Previdi, S., Shand, M., and C. Martin, "A Policy Control              Mechanism in IS-IS Using Administrative Tags",RFC 5130,              February 2008, <http://www.rfc-editor.org/info/rfc5130>.   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an              IANA Considerations Section in RFCs",BCP 26,RFC 5226,              May 2008, <http://www.rfc-editor.org/info/rfc5226>.   [RFC5311]  McPherson, D., Ginsberg, L., Previdi, S., and M. Shand,              "Simplified Extension of Link State PDU (LSP) Space for              IS-IS",RFC 5311, February 2009,              <http://www.rfc-editor.org/info/rfc5311>.   [RFC6233]  Li, T. and L. Ginsberg, "IS-IS Registry Extension for              Purges",RFC 6233, May 2011,              <http://www.rfc-editor.org/info/rfc6233>.   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code              Points",BCP 100,RFC 7120, January 2014,              <http://www.rfc-editor.org/info/rfc7120>.7.2.  Informative References   [RFC3563]  Zinin, A., "Cooperative Agreement Between the ISOC/IETF              and ISO/IEC Joint Technical Committee 1/Sub Committee 6              (JTC1/SC6) on IS-IS Routing Protocol Development",RFC3563, July 2003, <http://www.rfc-editor.org/info/rfc3563>.Ginsberg                     Standards Track                    [Page 6]

RFC 7370                  IS-IS TLV Codepoints            September 2014Acknowledgements   The author wishes to thank Alia Atlas and Amanda Baber for their   input in defining the correct process to follow to get these changes   implemented.  Special thanks to Adrian Farrel for crafting the text   inSection 4.Author's Address   Les Ginsberg   Cisco Systems   510 McCarthy Blvd.   Milpitas, CA  95035   United States   EMail: ginsberg@cisco.comGinsberg                     Standards Track                    [Page 7]