Internet DRAFT - draft-fairhurst-ipdvb-ule-iana
draft-fairhurst-ipdvb-ule-iana
IPDVB Working Group G. Fairhurst
Internet-Draft University of Aberdeen
Updates: 4326 (if approved) April 7, 2014
Intended status: Standards Track
Expires: October 9, 2014
IANA Guidance for Managing the ULE Next-Header Registry
draft-fairhurst-ipdvb-ule-iana-07
Abstract
This document updates 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.
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This Internet-Draft will expire on October 9, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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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 Registry . . . . . . . . . . . . . . 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. Expert Review Guidelines . . . . . . . . . . . . . . . . 5
3.3. Reservation of Next Header values for Private Use . . . . 5
4. Update to registry information . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. Revision Notes . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 8
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.
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o Section 3 specifies that new allocations in the ULE Next-Header
registry are to be assigned by IANA using the "Specification
Required" 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 Registry
The mandatory extension headers are allocated in the ULE Next Header
registry with integer values in the decimal range 0-255. The
registered value corresponds to a 16-bit Type value (converted by
setting the most significant 8-bits of the 16-bit value to zero).
This Type value may identify a mandatory extension header or a
specific protocol.
The optional extension headers are allocated in the ULE Next Header
registry with integer values in the decimal 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.
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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.
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 "Specification Required" 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 Designated Expert shall advise IANA on whether a
particular specification constitutes a standards document.
3.1. ULE Next-Header Registry
The ULE Next-Header registry allocates decimal values 0-511
(0x0000-0x01FF, hexadecimal). IANA must not allocate values greater
than 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 integer values in the
range 0-1535 (decimal). This forms the first part of the ULE Type
space (see [RFC4326] section 4.4.1).
The registry is divided into two ranges:
1. 0-255 (decimal) IANA-assigned values, indicating Mandatory
Extension Headers (or link-dependent Type fields). [RFC4326]
made initial assignments to this range of values in the registry,
updated by later requests.
2. 256-511 (decimal) IANA-assigned values, indicating Optional
Extension Headers. The entry MUST . 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.
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3.2. Expert Review Guidelines
The Specification Required policy also implies use of a Designated
Expert [RFC5226]. The Designated Expert shall review a proposed
registration for the following REQUIRED information:
For requests in the range 0-255 (decimal) - Mandatory Extension
Headers:
o The value and the name associated with the Extension Header;
o The procedure for processing the Extension Header;
o A definition of the Extension Header and the intended use;
o The size of the Extension Header (by default, the entire remaining
payload).
For requests in the range 256-511 (decimal) - Optional Extension
Headers:
o The value and the name associated with the Optional Extension
Header;
o The procedure for processing the Extension Header;
o A definition of the Extension Header and the intended use
(including any extension ordering requirements);
o The range of allowable H-LEN values that are permitted (in the
range 1-5).
If the registration information does not have any of the above
required information, the Designated Expert shall not approve the
registration to IANA.
3.3. Reservation of Next Header values for Private Use
This document reserves the range decimal 144-159 (0x80-0x8F,
hexadecimal) for Private Use [RFC5226].
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.
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Authors of specifications MUST 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 integer 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 integer 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.
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.
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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
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.
Draft 07
Update to incorporate IESG review feedback and comments from Pete
Resnick on specifically stating the Expert review requirements and
changing the definition to "Specification Required".
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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.
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
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