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Network Working Group                                        W. TownsleyRequest for Comments: 3438                                 Cisco SystemsBCP: 68                                                    December 2002Category: Best Current PracticeLayer Two Tunneling Protocol (L2TP)Internet Assigned Numbers Authority (IANA) Considerations UpdateStatus of this Memo   This document specifies an Internet Best Current Practices for the   Internet Community, and requests discussion and suggestions for   improvements.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2002).  All Rights Reserved.Abstract   This document describes updates to the Internet Assigned Numbers   Authority (IANA) considerations for the Layer Two Tunneling Protocol   (L2TP).Table of Contents1. Introduction.............................................11.1 Terminology...........................................22. IANA Considerations......................................22.1 Control Message AVPs..................................32.2 Message Type AVP Values...............................32.3 Result Code AVP Values................................32.4 Remaining Values......................................33. Normative References.....................................34. Security Considerations..................................45. Acknowledgements.........................................46. Author's Address.........................................47. Full Copyright Statement.................................51. Introduction   This document provides guidance to the Internet Assigned Numbers   Authority (IANA) regarding the registration of values related to the   Layer Two Tunneling Protocol (L2TP), defined in [RFC2661], in   accordance withBCP 26, [RFC2434].Townsley                 Best Current Practice                  [Page 1]

RFC 3438                L2TP IANA Considerations           December 20021.1 Terminology   The following terms are used here with the meanings defined inBCP 26:  "name space", "assigned value", "registration".   The following policies are used here with the meanings defined inBCP 26: "Private Use", "First Come First Served", "Expert Review",   "Specification Required", "IETF Consensus", "Standards Action".2. IANA Considerations   L2TP [RFC2661] defines a number of "magic" numbers to be maintained   by the IANA.  This section updates the criteria to be used by the   IANA to assign additional numbers in each of these lists.   Each of the values identified in this document that require a   registration criteria update are currently maintained by IANA and   have a range of values from 0 to 65 535, of which a very small number   have been allocated (the maximum number allocated within any one   range is 46) [L2TP-IANA].  Given the nature of these values, it is   not expected that any will ever run into a resource allocation   problem if registration allocation requirements are relaxed from   their current state.   The recommended criteria changes for IANA registration are listed in   the following sections.  In one case, the registration criteria is   currently defined as First Come First Served and should be made more   strict, others are defined as IETF Consensus and need to be relaxed.   The relaxation from IETF Consensus is motivated by specific cases in   which values that were never intended to be vendor-specific have had   to enter early field trials or be released in generally available   products with vendor-specific values while awaiting documents to be   formalized.  In most cases, this results in products that have to   support both the vendor-specific value and IETF value indefinitely.   For registration requests where a Designated Expert should be   consulted, the responsible IESG Area Director should appoint the   Designated Expert.   For registration requests requiring Expert Review, the Designated   Expert should consult relevant WGs as appropriate (e.g., the l2tpext   WG at the time of this writing).   The basic guideline for the Expert Review process will be to approve   the assignment of a value only if there is a document being advanced   that clearly defines the values to be assigned, and there is activeTownsley                 Best Current Practice                  [Page 2]

RFC 3438                L2TP IANA Considerations           December 2002   implementation development (perhaps entering early field or   interoperability trails, requiring assigned values to proceed without   having to resort to a chosen vendor-specific method).2.1 Control Message AVPs   IANA manages the "Control Message Attribute Value Pairs" [L2TP-IANA]   name space, of which 0 - 46 have been assigned.  The criteria for   assignment was originally IETF Consensus.  Further values should be   assigned upon Expert Review.2.2 Message Type AVP Values   IANA manages the "Message Type AVP (Attribute Type 0) Values" [L2TP-   IANA] name space, of which 0 - 16 have been assigned.  The criteria   for assignment was originally IETF Consensus.  Further values should   be assigned upon Expert Review.2.3 Result Code AVP Values   IANA maintains a list of "Result Code values for the StopCCN   message," "Result Code values for the CDN message," and "General   Error Codes" [L2TP-IANA].  The criteria for Error Code assignment was   originally First Come First Served, and the criteria for CDN and   StopCCN Result Codes were originally IETF Consensus.  Further values   for all Result and Error codes should be assigned upon Expert Review.2.4 Remaining Values   All criteria for L2TP values maintained by IANA and not mentioned   specifically in this document remain unchanged.3. Normative References   [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate               Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC2434]   Alvestrand, H. and T. Narten, "Guidelines for Writing an               IANA Considerations Section in RFCs",BCP 26,RFC 2434,               October 1998.   [RFC2661]   Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,               G. and B. Palter, "Layer Two Tunneling Layer Two               Tunneling Protocol (L2TP)",RFC 2661, August 1999.   [L2TP-IANA] Internet Assigned Numbers Authority (IANA), "Layer Two               Tunneling Protocol 'L2TP' -RFC 2661",http://www.iana.org/assignments/l2tp-parametersTownsley                 Best Current Practice                  [Page 3]

RFC 3438                L2TP IANA Considerations           December 20024. Security Considerations   This focuses on IANA considerations, and does not have security   considerations.5. Acknowledgements   Some of this text and much of the format of this document was taken   from an internet document on EAP IANA Considerations authored by   Bernard Aboba.6. Author's Address   W. Mark Townsley   Cisco Systems   7025 Kit Creek Road   PO Box 14987   Research Triangle Park, NC 27709   EMail: mark@townsley.netTownsley                 Best Current Practice                  [Page 4]

RFC 3438                L2TP IANA Considerations           December 20027.  Full Copyright Statement   Copyright (C) The Internet Society (2002).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Townsley                 Best Current Practice                  [Page 5]