IPDVB Working Group G. Fairhurst Internet-Draft University of Aberdeen Updates: 4326 (if approved) March 6, 2014 Intended status: Standards Track Expires: September 7, 2014 IANA Guidance for Managing the ULE Next-Header Registry draft-fairhurst-ipdvb-ule-iana-06 Abstract This document proposes an update to RFC 4326 to clarify and update the allocation rules for the Unidirectional Lightweight Encapsulation (ULE) Next-Header registry. This registry is used by ULE and Generic Stream Encapsulation (GSE) to record the code points of extension headers and protocols supported by these encapsulation protocols. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 7, 2014. Copyright Notice Copyright (c) 2014 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 (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 Fairhurst Expires September 7, 2014 [Page 1] Internet-Draft IANA ULE guidelines March 2014 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 2.1. The ULE Next Header Registries . . . . . . . . . . . . . 3 2.2. Informative example of using a value from the optional range . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Updated IANA guidance on allocation in the ULE Next Header Registry . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. ULE Next-Header Registry . . . . . . . . . . . . . . . . 4 3.2. IANA Guidelines . . . . . . . . . . . . . . . . . . . . . 4 3.3. Reservation of Next Header values for Private Use . . . . 5 4. Update to registry information . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 8. Revision Notes . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction The Unidirectional Lightweight Encapsulation (ULE) [RFC4326] specifies an encapsulation for links that employ the MPEG-2 Transport Stream, with support over a wide variety of physical-layer bearers [RFC4259]. The encapsulation header includes a Type field that identifies payload types and extension headers (e.g.[RFC5163]). The ULE specification requested IANA to maintain the ULE next header registries to record the allocation of the values used to derive this Type field. The Digital Video Broadcast (DVB) Project has published an encapsulation for second-generation DVB physical layers. This specifies the Generic Stream Encapsulation [GSE]. This encapsulation shares many of the network properties of ULE and uses a common format for the Type field [RFC5163]. The ULE Next Header registries are therefore also applicable to this encapsulation. This document updates the IANA rules and guidance defined in section 11.1 of [RFC4326] in the following way: o The document clarifies use of the ULE Next-Header registry by GSE as well as for ULE. Fairhurst Expires September 7, 2014 [Page 2] Internet-Draft IANA ULE guidelines March 2014 o Section 3 specifies that new allocations in the ULE Next-Header registry are to be assigned by IANA using the "Expert Review" policy and provides guidance to the expert reviewer. o Section 3.3 reserves a range of allocated values. o Section 4 adds an explanatory note to clarify the encoding used in the ULE Next-Header registry. 2. Terminology This document assumes familiarity with the terminology of ULE [RFC4326] and [RFC5163]. 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 in [RFC2119]. 2.1. The ULE Next Header Registries The mandatory extension headers are allocated in the ULE Next Header registry with decimal values in the range 0-255. The registered value corresponds to the 16-bit Type value for the mandatory extension header or to identify a specific protocol. The optional extension headers are allocated in the ULE Next Header registry with decimal values in the range 256-511. The registered value corresponds to the 16-bit Type value that would be used for an optional extension header with a length (H-LEN) of 1. 2.2. Informative example of using a value from the optional range This section provides an informative example of how a registry entry is constructed to identify an optional ULE extension header. Values registered by IANA in the optional ULE extension header range correspond to a 16-bit Type value with the H-LEN field (in bits 5 to 7) set to a decimal value of 1. This registration format is used irrespective of the H-LEN value to be used. Bits 8 to 15 of the value in the registry are combined with the actual required H-LEN value (bits 5 to 7) to form the 16-bit Type field. For example, the decimal value 256 has been allocated to denote the padding extension header. o Type value 256: When a 2-byte padding extension header is used, the H-LEN is 1, resulting in a Type value with a decimal value of 256 (as allocated), corresponding to a hexadecimal value of 0x100. Fairhurst Expires September 7, 2014 [Page 3] Internet-Draft IANA ULE guidelines March 2014 o Type value 768: When a 6-byte padding extension header is used, the H-LEN is 3, resulting in a Type value with a decimal value of 768, corresponding to a hexadecimal value of 0x300. 3. Updated IANA guidance on allocation in the ULE Next Header Registry The rules for allocation were defined in section 11 of [RFC4326]. This document updates these rules by replacing them with the rules in this section: Allocations in the ULE Next-Header Registry are to be assigned by IANA using the "Expert Review" policy defined in [RFC5226]. Applications must include a reference to a specification of the next header extension in a standards document. An IETF standards-track RFC can provide such a reference. Other specifications are also permitted. The expert shall advise IANA on whether a particular specification constitutes a standards document. 3.1. ULE Next-Header Registry This registry allocates Next-Header values within the range 0-511 (decimal). For each allocated value, it also specifies the set of allowed H-LEN values (see [RFC4326] section 5). The combination of the IANA-registered value and the H-LEN are used by ULE and GSE to derive a set of allowed 16-bit values in the decimal range 0-1535. This forms the first part of the ULE Type space (see [RFC4326] section 4.4.1). 3.2. IANA Guidelines The following contains the IANA guidelines for management of the ULE Next-Header registry. This registry allocates decimal values 0-511 (0x0000-0x01FF, hexadecimal). IANA MUST NOT allocate values greater than 511 (decimal). The ULE Next-Header registry is divided into two ranges: 1. 0-255 (decimal) IANA-assigned values, indicating Mandatory Extension Headers (or link-dependent Type fields). Requests for assignment in this range MUST define the value and the name associated with the Extension Header, together with the procedure for processing the Extension Header. This MUST also define the need for the Mandatory Extension and the intended use. [RFC4326] made initial assignments to this range of values in the registry, updated by later requests. The size of the Extension Header MUST be specified (by default the entire remaining payload). Fairhurst Expires September 7, 2014 [Page 4] Internet-Draft IANA ULE guidelines March 2014 2. 256-511 (decimal) IANA-assigned values, indicating Optional Extension Headers. Requests for assignment in this range MUST define the value and the name associated with the Extension Header, together with the procedure for processing the Extension Header. The entry MUST specify the range of allowable H-LEN values that are permitted (in the range 1-5). It MUST also define the need for the Optional Extension and the intended use. [RFC4326] made initial assignments to this range of values in the registry, updated by later requests. 3.3. Reservation of Next Header values for Private Use This document reserves the range decimal 144-159 (0x80-0x8F, hexadecimal) for Private Use. These values are not available for allocation by IANA. Appropriate use includes development of experimental options for which either no general-purpose solution was planned, where insufficient operational experience was available to understand if a general solution is needed, or where a more general solution is not yet mature. This use is not coordinated between users of these values, so the uniqueness of a particular value can not be guaranteed. Authors of specifications (see Section 3.0) SHOULD contact IANA to request a new value to be allocated in the ULE Next-Header registry. An IANA-allocated value uniquely identifies the method. Such an allocation is REQUIRED for any method that is to be standardised. 4. Update to registry information This section requests IANA to record an additional explanatory note in the ULE Next-Header registry: "The Mandatory Extension Header range in the ULE Next-Header registry is used to allocate values in the range 0-255 (decimal). These values are used to identify mandatory extension headers. The registered value corresponds to the 16-bit Type value for the mandatory extension header or the specified protocol. The Optional Extension Header range in the ULE Next-Header registry is used to allocate values in the range 256-511 (decimal). These values are used to identify optional extension headers. The registered value corresponds to the 16-bit Type value that would be used for an optional extension header with a header length (H-LEN) of 1." This additional note should be placed before the current note. Fairhurst Expires September 7, 2014 [Page 5] Internet-Draft IANA ULE guidelines March 2014 5. Security Considerations This document does not present new security considerations. 6. IANA Considerations Section 3 specifies updated IANA allocation rules Section 3.3 requests IANA to reserve the range decimal 144-159 (0x80-0x8F, hexadecimal) and to mark this as Reserved for Private Use. Section 4 requests IANA to update the ULE Next-Header registry information. 7. Acknowledgments The author acknowledges feedback from IANA, Thomas Narten, Margaret Wasserman, and Wes Eddy and the IETF Gen-ART team. Helpful reviews and comments were also received from Alexander Adolf and Hans-Peter Lexow on usage of this registry. 8. Revision Notes RFC-Editor: Please remove this section prior to publication Draft 00 This was the first revision - it proposed the requested update. Draft 01 This revision is thought complete and replaces the entire IANA section with the new text. Draft 02 Section 1 includes an overview of the changes from RFC 4326, requested by Margaret Wasserman. Draft 03 Reworded section 3.1 to clarify difference between registered value and derived Type field value, requested by Michelle Cotton. Clarified each value as being decimal or hexadecimal. Draft 04 Fairhurst Expires September 7, 2014 [Page 6] Internet-Draft IANA ULE guidelines March 2014 No changes made, this draft was updated ready for submission to the Area Director. Draft 05 Updated discussion of the private address range, and how this should be used. Fixed NiT in intro, now correctly indicating range: 256-511. Draft 06 Update to incorporate Gen-ART review feedback and LC comments from Alexander Adolf with a suggested informative example. 9. References 9.1. Normative References [GSE] European Telecommunication Standards, Institute (ETSI), "Digital Video Broadcasting (DVB); Generic Stream Encapsulation (GSE) Protocol", 2007. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4326] Fairhurst, G. and B. Collini-Nocker, "Unidirectional Lightweight Encapsulation (ULE) for Transmission of IP Datagrams over an MPEG-2 Transport Stream (TS)", RFC 4326, December 2005. [RFC5163] Fairhurst, G. and B. Collini-Nocker, "Extension Formats for Unidirectional Lightweight Encapsulation (ULE) and the Generic Stream Encapsulation (GSE)", RFC 5163, April 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. 9.2. Informative References [RFC4259] Montpetit, M., Fairhurst, G., Clausen, H., Collini-Nocker, B., and H. Linder, "A Framework for Transmission of IP Datagrams over MPEG-2 Networks", RFC 4259, November 2005. Fairhurst Expires September 7, 2014 [Page 7] Internet-Draft IANA ULE guidelines March 2014 Author's Address Godred Fairhurst University of Aberdeen School of Engineering Fraser Noble Building Aberdeen, Scotland AB24 3UE UK Email: gorry@erg.abdn.ac.uk URI: http://www.erg.abdn.ac.uk Fairhurst Expires September 7, 2014 [Page 8]